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  • 2751.
    Wästlund, Johan
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Two-person symmetric whist2005Inngår i: The Electronic Journal of Combinatorics, ISSN 1097-1440, E-ISSN 1077-8926, Vol. 12, nr 1, s. R44-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We introduce a two-person perfect information model of trick taking games. A set of cards is distributed between two players, and play proceeds in tricks with the obligation to follow suit, as in many real-world card games.

    We assume that in each suit, the two players have the same number of cards. Under this assumption, we show how to assign a value from a  certain semigroup to each single-suit card distribution in such a way that the outcome of a multi-suit deal under optimal play is determined by the sum of the values of the individual suits.

  • 2752.
    Xie, Yi
    et al.
    Wuhan Engineering Consulting Bureau, Wuhan, China.
    Takala, Josu
    Faculty of TechnologyUniversity of Vaasa, Vaasa, Finland.
    Liu, Yang
    Faculty of TechnologyUniversity of Vaasa, Vaasa, Finland.
    Chen, Yong
    Old Dominion University, Norfolk, USA.
    A combinatorial optimization model for enterprise patent transfer2015Inngår i: Journal of Special Topics in Information Technology and Management, ISSN 1385-951X, E-ISSN 1573-7667, Vol. 16, nr 4, s. 327-337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Enterprises need patent transfer strategies to improve their technology management. This paper proposes a combinatorial optimization model that is based on intelligent computing to support enterprises’ decision making in developing patent transfer strategy. The model adopts the Black–Scholes Option Pricing Model and Arbitrage Pricing Theory to estimate a patent’s value. Based on the estimation, a hybrid genetic algorithm is applied that combines genetic algorithms and greedy strategy for the optimization purpose. Encode repairing and a single-point crossover are applied as well. To validate this proposed model, a case study is conducted. The results indicate that the proposed model is effective for achieving optimal solutions. The combinatorial optimization model can help enterprise promote their benefits from patent sale and support the decision making process when enterprises develop patent transfer strategies.

  • 2753.
    Yan, Ping
    Linköpings universitet, Institutionen för datavetenskap, Statistik och maskininlärning.
    Anomaly Detection in Categorical Data with Interpretable Machine Learning: A random forest approach to classify imbalanced data2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Metadata refers to "data about data", which contains information needed to understand theprocess of data collection. In this thesis, we investigate if metadata features can be usedto detect broken data and how a tree-based interpretable machine learning algorithm canbe used for an effective classification. The goal of this thesis is two-fold. Firstly, we applya classification schema using metadata features for detecting broken data. Secondly, wegenerate the feature importance rate to understand the model’s logic and reveal the keyfactors that lead to broken data.

    The given task from the Swedish automotive company Veoneer is a typical problem oflearning from extremely imbalanced data set, with 97 percent of data belongs healthy dataand only 3 percent of data belongs to broken data. Furthermore, the whole data set containsonly categorical variables in nominal scales, which brings challenges to the learningalgorithm. The notion of handling imbalanced problem for continuous data is relativelywell-studied, but for categorical data, the solution is not straightforward.

    In this thesis, we propose a combination of tree-based supervised learning and hyperparametertuning to identify the broken data from a large data set. Our methods arecomposed of three phases: data cleaning, which is eliminating ambiguous and redundantinstances, followed by the supervised learning algorithm with random forest, lastly, weapplied a random search for hyper-parameter optimization on random forest model.

    Our results show empirically that tree-based ensemble method together with a randomsearch for hyper-parameter optimization have made improvement to random forest performancein terms of the area under the ROC. The model outperformed an acceptableclassification result and showed that metadata features are capable of detecting brokendata and providing an interpretable result by identifying the key features for classificationmodel.

    Fulltekst (pdf)
    fulltext
  • 2754.
    Yang, Xiangfeng
    Linköpings universitet, Matematiska institutionen, Matematisk statistik. Linköpings universitet, Tekniska fakulteten.
    Asymptotic expansions for Laplace transforms of Markov processes2018Inngår i: Journal of Mathematical Analysis and Applications, ISSN 0022-247X, E-ISSN 1096-0813, Vol. 457, nr 1, s. 694-721Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Let mu(epsilon) be the probability measures on D[0,T] of suitable Markov processes {xi(epsilon)(t)}0 amp;lt;= t amp;lt;= T (possibly with small jumps) depending on a small parameter epsilon amp;gt;0, where D[0,T] denotes the space of all functions on [0, T] which are right continuous with left limits. In this paper we investigate asymptotic expansions for the Laplace transforms integral(D[0,T]) exp{epsilon F-1(x)}mu(epsilon)(dx) as epsilon -amp;gt; 0 for smooth functionals F on D[0,T]. This study not only recovers several well-known results, but more importantly provides new expansions for jump Markov processes. Besides several standard tools such as exponential change of measures and Taylors expansions, the novelty of the proof is to implement the expectation asymptotic expansions on normal deviations which were recently derived in [13]. (c) 2017 Elsevier Inc. All rights reserved.

  • 2755.
    Yang, Xiangfeng
    Linköpings universitet, Matematiska institutionen, Matematisk statistik. Linköpings universitet, Tekniska högskolan.
    Exact upper tail probabilities of random series2015Inngår i: Statistics and Probability Letters, ISSN 0167-7152, E-ISSN 1879-2103, Vol. 99, s. 13-19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we obtain new estimates on upper tail probabilities of suitable random series involving a distribution having an exponential tail. These estimates are exact, and the distribution is not heavy-tailed.

  • 2756.
    Yang, Xiangfeng
    Linköpings universitet, Matematiska institutionen, Matematisk statistik. Linköpings universitet, Tekniska fakulteten.
    On the large deviation principle of generalized Brownian bridges2015Inngår i: Journal of Mathematical Analysis and Applications, ISSN 0022-247X, E-ISSN 1096-0813, Vol. 430, nr 2, s. 845-856Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we consider a family of generalized Brownian bridges with a small noise, which was used by Brennan and Schwartz [3] to model the arbitrage profit in stock index futures in the absence of transaction costs. More precisely, we study the large deviation principle of these generalized Brownian bridges as the noise becomes infinitesimal. (C) 2015 Elsevier Inc. All rights reserved.

  • 2757. Bestill onlineKjøp publikasjonen >>
    Ying, Daniel
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Cyclic Trigonal Riemann Surfaces of Genus 42004Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    A closed Riemann surface which can be realized as a 3-sheeted covering of the Riemann sphere is called trigonal, and such a covering is called a trigonal morphism. Accola showed that the trigonal morphism is unique for Riemann surfaces of genus g ≥ 5. This thesis will characterize the Riemann surfaces of genus 4 wiht non-unique trigonal morphism. We will describe the structure of the space of cyclic trigonal Riemann surfaces of genus 4.

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  • 2758.
    Ying, Daniel
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Matematiska institutionen, Tillämpad matematik.
    Klassificering av automorfigrupper på trigonala Riemannytor2003Inngår i: Unga matematiker Svenska matematikersamfundets höstmöte,2003, 2003Konferansepaper (Annet vitenskapelig)
  • 2759.
    Ying, Daniel
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Matematiska institutionen, Tillämpad matematik.
    Kubiska riemannytor2004Inngår i: Workshop i tillämpad matematik,2004, 2004Konferansepaper (Annet vitenskapelig)
  • 2760. Bestill onlineKjøp publikasjonen >>
    Ying, Daniel
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    On the Moduli Space of Cyclic Trigonal Riemann Surfaces of Genus 42006Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    A closed Riemann surface which can be realized as a 3-sheeted covering of the Riemann sphere is called trigonal, and such a covering is called a trigonal morphism. Accola showed that the trigonal morphism is unique for Riemann surfaces of genus g ≥ 5. This thesis characterizes the cyclic trigonal Riemann surfaces of genus 4 with non-unique trigonal morphism using the automorphism groups of the surfaces. The thesis shows that Accola’s bound is sharp with the existence of a uniparametric family of cyclic trigonal Riemann surfaces of genus 4 having several trigonal morphisms. The structure of the moduli space of trigonal Riemann surfaces of genus 4 is also characterized.

    Finally, by using the same technique as in the case of cyclic trigonal Riemann surfaces of genus 4, we are able to deal with p-gonal Riemann surfaces and show that Accola’s bound is sharp for p-gonal Riemann surfaces. Furthermore, we study families of p-gonal Riemann surfaces of genus (p − 1)2 with two p-gonal morphisms, and describe the structure of their moduli space.

    Fulltekst (pdf)
    FULLTEXT01
  • 2761.
    You, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Load Optimization With User Association in Cooperative and Load-Coupled LTE Networks2017Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, nr 5, s. 3218-3231Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We extend the problem of optimizing user association for load balancing in cellular networks along 2-dimensions. First, we consider joint transmission, which is one of the coordinated multipoint techniques with which a user may be simultaneously served by multiple base stations. Second, we account for, mathematically, the coupling relation between the base stations load levels that are dependent on each other due to inter-cell interference. We formulate two optimization problems, sum load minimization (MinSumL) and maximum load minimization (MinMaxL). We prove that both MinSumL and MinMaxL are NP-hard. We propose a mixed integer linear programming based scheme by means of linearization. This approach also leads to a bounding scheme for performance benchmarking. Then, we derive a set of partial optimality conditions. Fulfillment of the conditions will guarantee performance improvement for both MinSumL and MinMaxL. A solution algorithm is then derived based on the conditions. Simulation results are provided to demonstrate the effectiveness of the approaches.

    Fulltekst (pdf)
    fulltext
  • 2762.
    Yung, Tamara
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Traffic Modelling Using Parabolic Differential Equations2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The need of a working infrastructure in a city also requires an understanding of how the traffic flows. It is known that increasing number of drivers prolong the travel time and has an environmental effect in larger cities. It also makes it more difficult for commuters and delivery firms to estimate their travel time. To estimate the traffic flow the traffic department can arrange cameras along popular roads and redirect the traffic, but this is a costly method and difficult to implement. Another approach is to apply theories from physics wave theory and mathematics to model the traffic flow; in this way it is less costly and possible to predict the traffic flow as well. This report studies the application of wave theory and expresses the traffic flow as a modified linear differential equation. First is an analytical solution derived to find a feasible solution. Then a numerical approach is done with Taylor expansions and Crank-Nicolson’s method. All is performed in Matlab and compared against measured values of speed and flow retrieved from Swedish traffic department over a 24 hours traffic day. The analysis is performed on a highway stretch outside Stockholm with no entries, exits or curves. By dividing the interval of the highway into shorter equal distances the modified linear traffic model is expressed in a system of equations. The comparison between actual values and calculated values of the traffic density is done with a nominal average difference. The results reveal that the numbers of intervals don’t improve the average difference. As for the small constant that is applied to make the linear model stable is higher than initially considered.

    Fulltekst (pdf)
    fulltext
  • 2763.
    Zahlin, Ann-Sofie
    Linköpings universitet, Institutionen för utbildningsvetenskap.
    Laborativt arbetssätt i matematik: lärares förhållande till det laborativa arbetssättet i matematikundervisningen2001Independent thesis Basic level (professional degree)Oppgave
    Abstract [sv]

    Studien syftar till att studera ett laborativt arbetssätt i matematiken som metod. Arbetet består av en litteraturgenomgång och en empirisk del där intervjuer med åtta olika lärare ingår.

    Den teoretiska delen behandlar två områden. Dessa områden är ämnet matematik och vad ett laborativt arbetssätt är utifrån litteraturen. Den teoretiska studien beskriver hur ett laborativt arbetssätt i matematikundervisningen kan se ut. Vad eleven och läraren gör i skolmatematikens sex områden: Aritmetik, algebra, geometri, sannolikhetslära, statestik och funktionslära. Avslutningsvis finns en pedagogisk syn på arbetssättet. Den empiriska delen är en sammanfattning i form av intervjuer med åtta lärare i matematik.

    I resultatdelen får vi möta lärarnas svar på vad ett laborativt arbetssätt är, varför/varför inte man undervisar laborativt i matematik, inom vilka områden i skolmatematiken arbetssättet används och vilka yttre villkor som styr arbetssättet. Lärarnas uppfattningar om det laborativa arbetssättet stämmer i stort sett överens med litteraturen. Det krävs en hel del engagemang av läraren innan arbetssättet fungerar i praktiken.

    Fulltekst (pdf)
    FULLTEXT01
  • 2764.
    Zhang, Yingfeng
    et al.
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, School of Mechanical Engineering, Northwestern Polytechnical University, Shaanxi, China.
    Liu, Sichao
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, School of Mechanical Engineering, Northwestern Polytechnical University, Shaanxi, China.
    Liu, Yang
    Department of Production, University of Vaasa, Vaasa, Finland.
    Li, Rui
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, School of Mechanical Engineering, Northwestern Polytechnical University, Shaanxi, China.
    Smart box-enabled product–service system for cloud logistics2016Inngår i: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 54, nr 22, s. 6693-6706Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modern logistics takes significant progress and rapid developments with the prosperity of E-commerce, particularly in China. Typical challenges that logistics industry is facing now are composed by a lack of sharing, standard, cost-effective and environmental package and efficient optimisation method for logistics tasks distribution. As a result, it is difficult to implement green, sustainable logistics services. Three important technologies, Physical Internet (PI), product–service system (PSS) and cloud computing (CC), are adopted and developed to address the above issues. PI is extended to design a world-standard green recyclable smart box that is used to encapsulate goods. Smart box-enabled PSS is constructed to provide an innovative sustainable green logistics service, and high-quality packaging, as well as reduce logistics cost and environmental pollution. A real-time information-driven logistics tasks optimisation method is constructed by designing a cloud logistics platform based on CC. On this platform, a hierarchical tree-structure network for customer orders (COs) is built up to achieve the order-box matching of function. Then, a distance clustering analysis algorithm is presented to group and form the optimal clustering results for all COs, and a real-time information-driven optimisation method for logistics orders is proposed to minimise the unused volume of containers. Finally, a case study is simulated to demonstrate the efficiency and feasibility of proposed cloud logistics optimisation method. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

  • 2765.
    Zhao, Hongmei
    et al.
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska högskolan.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska högskolan.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska högskolan.
    Power efficient uplink scheduling in SC-FDMA: Bounding global optimality by column generation2013Inngår i: 2013 IEEE 18th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD, IEEE , 2013, s. 119-123Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We study resource allocation in cellular systems and consider the problem of finding a power efficient scheduling in an uplink single carrier frequency division multiple access (SC-FDMA) system with localized allocation of subcarriers, that is, the subcarriers allocated to a user equipment have to be consecutive in the frequency domain in each time slot. This problem is discrete and nonconvex, thus the use of suboptimal algorithms has been a common practice. We leverage the power of mathematical programming in order to approach global optimality or a tight bounding interval confining global optimum, to arrive at an effective scheme for gauging the performance of suboptimal algorithms. Toward this end, we first provide a straightforward integer linear programming formulation, and then an alternative and less trivial, so-called column-oriented, formulation. The latter is solved by column generation, which is a solution technique for large-scale optimization problems with certain characteristics. The computational evaluation demonstrates that the column generation method produces very highquality subcarrier allocations that either coincide with the global optimum or enable an extremely sharp bounding interval. Hence the approach serves well for the purpose of benchmarking results for large-scale instances of power efficient SC-FDMA scheduling.

  • 2766.
    Zhao, Yixin
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    On the Integration of Heuristics with Column-Oriented Models for Discrete Optimization2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Column-oriented models are today common in the eld of discrete optimization, and there is an increasing interest in using such models as a basis for heuristic solution methods. The common theme of this work is to explore some possibilities to integrate heuristic principles and column-oriented models for discrete optimization problems.

    In the rst paper, we consider a resource allocation problem for cellular systems. We propose a strong column-oriented formulation and a corresponding column generation method, as well as an enhanced column generation scheme for this problem. The enhanced scheme is composed of a stabilization technique, an approximate column generation principle, and, for nding integer solutions, a heuristic that is embedded in the column generation scheme.

    The second paper provides a new and strong convexied formulation of the xed charge transportation problem. This formulation is obtained by integrating the concepts of Lagrangian decomposition and column generation. It is shown both theoretically and practically that this integration yields a formulation which is stronger than three other convexied formulations of the problem.

    Delarbeid
    1. Power efficient uplink scheduling in SC-FDMA: benchmarking by column generation
    Åpne denne publikasjonen i ny fane eller vindu >>Power efficient uplink scheduling in SC-FDMA: benchmarking by column generation
    Vise andre…
    2016 (engelsk)Inngår i: Optimization and Engineering, ISSN 1389-4420, E-ISSN 1573-2924, Vol. 17, nr 4, s. 695-725Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We study resource allocation in cellular systems and consider the problem of finding a power efficient scheduling in an uplink single carrier frequency division multiple access system. Due to the discrete nature of this problem and its computational difficulty, particularly in a real-time setting, the use of suboptimal algorithms is common practice. We aim at an effective way of gauging the performance of suboptimal algorithms by finding tight bounds on the global optimum. Toward this end, we first provide a basic integer linear programming formulation. Then we propose a significantly stronger column-oriented formulation and a corresponding column generation method, as well as an enhanced column generation scheme. The latter extends the first scheme through the inclusion of a stabilization technique, an approximate column generation principle, and a tailored heuristic that is embedded in the column generation scheme to find high-quality though not necessarily global optimal solutions. The computational evaluation demonstrates that compared with a poor performance by the integer linear programming formulation, the column generation method can produce near-optimal schedules that enable a sharp bounding interval. The enhanced column generation method significantly sharpens the bounding interval. Hence the column generation approach serves well for the purpose of benchmarking results for large-scale instances.

    sted, utgiver, år, opplag, sider
    Springer-Verlag New York, 2016
    Emneord
    Localized SC-FDMA, Stabilized column generation, Power minimization, Integer linear programming, Uplink scheduling, Matheuristic
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-127355 (URN)10.1007/s11081-015-9304-z (DOI)000387857500004 ()
    Merknad

    Funding agencies: Research School in Interdisciplinary Mathematics at Linkoping University; Excellence Center at Linkoping - Lund in Information Technology, Centrum for Industriell Informationsteknologi, Linkoping University, EC FP7 Marie Curie Project [318992]; Chinese Sc

    Tilgjengelig fra: 2016-04-22 Laget: 2016-04-22 Sist oppdatert: 2019-08-06bibliografisk kontrollert
    2. Power efficient uplink scheduling in SC-FDMA: Bounding global optimality by column generation
    Åpne denne publikasjonen i ny fane eller vindu >>Power efficient uplink scheduling in SC-FDMA: Bounding global optimality by column generation
    Vise andre…
    2013 (engelsk)Inngår i: 2013 IEEE 18th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD, IEEE , 2013, s. 119-123Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    We study resource allocation in cellular systems and consider the problem of finding a power efficient scheduling in an uplink single carrier frequency division multiple access (SC-FDMA) system with localized allocation of subcarriers, that is, the subcarriers allocated to a user equipment have to be consecutive in the frequency domain in each time slot. This problem is discrete and nonconvex, thus the use of suboptimal algorithms has been a common practice. We leverage the power of mathematical programming in order to approach global optimality or a tight bounding interval confining global optimum, to arrive at an effective scheme for gauging the performance of suboptimal algorithms. Toward this end, we first provide a straightforward integer linear programming formulation, and then an alternative and less trivial, so-called column-oriented, formulation. The latter is solved by column generation, which is a solution technique for large-scale optimization problems with certain characteristics. The computational evaluation demonstrates that the column generation method produces very highquality subcarrier allocations that either coincide with the global optimum or enable an extremely sharp bounding interval. Hence the approach serves well for the purpose of benchmarking results for large-scale instances of power efficient SC-FDMA scheduling.

    sted, utgiver, år, opplag, sider
    IEEE, 2013
    Serie
    International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), ISSN 2378-4865 ; 2013
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-106237 (URN)10.1109/CAMAD.2013.6708101 (DOI)
    Konferanse
    2013 IEEE 18th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD)
    Tilgjengelig fra: 2014-04-29 Laget: 2014-04-29 Sist oppdatert: 2018-06-25
    Download (pdf)
    omslag
    Download (jpg)
    presentationsbild
  • 2767.
    Zhao, Yixin
    et al.
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    A Large Neighbourhood Search Principle for Column-Oriented Models: Theoretical Derivation and Example Applications2016Inngår i: Matheuristics 2016: Proceedings of the Sixth International Workshop on Model-based Metaheuristics / [ed] V. Maniezzo and T. Stutzle, Bruxelles, Belgium: IRIDIA , 2016Konferansepaper (Fagfellevurdert)
  • 2768.
    Zhao, Yixin
    et al.
    Nanjing University of Science and Technology, School of Automation.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    An integer programming column generation principlefor heuristic search methods2019Inngår i: International Transactions in Operational Research, ISSN 0969-6016, E-ISSN 1475-3995, Vol. 27, nr 1, s. 665-695Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is an increasing interest in integrating column generation and heuristic approaches to efficiently solve large-scale discrete optimisation problems. We contribute in this direction. Based on the insights from Lagrangian duality theory, we present an auxiliary problem that can be used for finding near-optimal solutions to a discrete column-oriented model. The structure of this auxiliary problem makes it suitable for being addressed with a heuristic search method involving column generation. To this end, we suggest a large neighbourhood search strategy where the repair step is to solve a column generation type subproblem. The suggested search strategy and mathematical models involved need to be tailored to the problem structure. To illustrate important design options and computational behaviour, four applications are studied: bin packing, generalised assignment, a resource allocation problem and the fixed-charge transportation problem.

  • 2769.
    Zhao, Yixin
    et al.
    Nanjing University of Science and Technology, School of Automation.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Pardalos, Panos
    University of Florida, Department of Industrial and System Engineering.
    The fixed charge transportation problem: a strong formulation based on Lagrangian decomposition and column generation2018Inngår i: Journal of Global Optimization, ISSN 0925-5001, E-ISSN 1573-2916, Vol. 72, nr 3, s. 517-538Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new and strong convexified formulation of the fixed charge transportation problem is provided. This formulation is obtained by integrating the concepts of Lagrangian decomposition and column generation. The decomposition is made by splitting the shipping variables into supply and demand side copies, while the columns correspond to extreme flow patterns for single sources or sinks. It is shown that the combination of Lagrangian decomposition and column generation provides a formulation whose strength dominates those of three other convexified formulations of the problem. Numerical results illustrate that our integrated approach has the ability to provide strong lower bounds. The Lagrangian decomposition yields a dual problem with an unbounded set of optimal solutions. We propose a regularized column generation scheme which prioritizes an optimal dual solution with a small 1-norm. We further demonstrate numerically that information gained from the strong formulation can also be used for constructing a small-sized core problem which yields high-quality upper bounds.

  • 2770.
    Zhao, Yixin
    et al.
    Nanjing Univ Sci and Technol, Peoples R China.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Correction: Power efficient uplink scheduling in SC-FDMA: benchmarking by column generation (vol 17, pg 695, 2016)2019Inngår i: Optimization and Engineering, ISSN 1389-4420, E-ISSN 1573-2924, Vol. 20, nr 3, s. 959-959Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    At the time of the final publication of the paper, in December 2016, Yixin Zhaos affiliation had changed.

  • 2771.
    Zhao, Yixin
    et al.
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Larsson, Torbjörn
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Rönnberg, Elina
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Lei, Lei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Power efficient uplink scheduling in SC-FDMA: benchmarking by column generation2016Inngår i: Optimization and Engineering, ISSN 1389-4420, E-ISSN 1573-2924, Vol. 17, nr 4, s. 695-725Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study resource allocation in cellular systems and consider the problem of finding a power efficient scheduling in an uplink single carrier frequency division multiple access system. Due to the discrete nature of this problem and its computational difficulty, particularly in a real-time setting, the use of suboptimal algorithms is common practice. We aim at an effective way of gauging the performance of suboptimal algorithms by finding tight bounds on the global optimum. Toward this end, we first provide a basic integer linear programming formulation. Then we propose a significantly stronger column-oriented formulation and a corresponding column generation method, as well as an enhanced column generation scheme. The latter extends the first scheme through the inclusion of a stabilization technique, an approximate column generation principle, and a tailored heuristic that is embedded in the column generation scheme to find high-quality though not necessarily global optimal solutions. The computational evaluation demonstrates that compared with a poor performance by the integer linear programming formulation, the column generation method can produce near-optimal schedules that enable a sharp bounding interval. The enhanced column generation method significantly sharpens the bounding interval. Hence the column generation approach serves well for the purpose of benchmarking results for large-scale instances.

    Fulltekst (pdf)
    fulltext
  • 2772. Bestill onlineKjøp publikasjonen >>
    Zhao, Yuxin
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Position Estimation in Uncertain Radio Environments and Trajectory Learning2017Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    To infer the hidden states from the noisy observations and make predictions based on a set of input states and output observations are two challenging problems in many research areas. Examples of applications many include position estimation from various measurable radio signals in indoor environments, self-navigation for autonomous cars, modeling and predicting of the traffic flows, and flow pattern analysis for crowds of people. In this thesis, we mainly use the Bayesian inference framework for position estimation in an indoor environment, where the radio propagation is uncertain. In Bayesian inference framework, it is usually hard to get analytical solutions. In such cases, we resort to Monte Carlo methods to solve the problem numerically. In addition, we apply Bayesian nonparametric modeling for trajectory learning in sport analytics.

    The main contribution of this thesis is to propose sequential Monte Carlo methods, namely particle filtering and smoothing, for a novel indoor positioning framework based on proximity reports. The experiment results have been further compared with theoretical bounds derived for this proximity based positioning system. To improve the performance, Bayesian non-parametric modeling, namely Gaussian process, has been applied to better indicate the radio propagation conditions. Then, the position estimates obtained sequentially using filtering and smoothing are further compared with a static solution, which is known as fingerprinting.

    Moreover, we propose a trajectory learning framework for flow estimation in sport analytics based on Gaussian processes. To mitigate the computation deficiency of Gaussian process, a grid-based on-line algorithm has been adopted for real-time applications. The resulting trajectory modeling for individual athlete can be used for many purposes, such as performance prediction and analysis, health condition monitoring, etc. Furthermore, we aim at modeling the flow of groups of athletes, which could be potentially used for flow pattern recognition, strategy planning, etc.

    Delarbeid
    1. Received-Signal-Strength Threshold Optimization Using Gaussian Processes
    Åpne denne publikasjonen i ny fane eller vindu >>Received-Signal-Strength Threshold Optimization Using Gaussian Processes
    2017 (engelsk)Inngår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 65, nr 8, s. 2164-2177Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    There is a big trend nowadays to use event-triggered proximity report for indoor positioning. This paper presents a generic received-signal-strength (RSS) threshold optimization framework for generating informative proximity reports. The proposed framework contains five main building blocks, namely the deployment information, RSS model, positioning metric selection, optimization process and management. Among others, we focus on Gaussian process regression (GPR)-based RSS models and positioning metric computation. The optimal RSS threshold is found through minimizing the best achievable localization root-mean-square-error formulated with the aid of fundamental lower bound analysis. Computational complexity is compared for different RSS models and different fundamental lower bounds. The resulting optimal RSS threshold enables enhanced performance of new fashioned low-cost and low-complex proximity report-based positioning algorithms. The proposed framework is validated with real measurements collected in an office area where bluetooth-low-energy (BLE) beacons are deployed.

    sted, utgiver, år, opplag, sider
    Institute of Electrical and Electronics Engineers (IEEE), 2017
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-135065 (URN)10.1109/TSP.2017.2655480 (DOI)000395827100018 ()
    Prosjekter
    TRAX
    Merknad

    Funding agencies: European Union FP7 Marie Curie training programme on Tracking in Complex Sensor Systems [607400]

    Tilgjengelig fra: 2017-03-08 Laget: 2017-03-08 Sist oppdatert: 2019-02-12bibliografisk kontrollert
    2. Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning
    Åpne denne publikasjonen i ny fane eller vindu >>Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning
    Vise andre…
    2016 (engelsk)Inngår i: 2016 IEEE 83rd Vehicular Technology Conference (VTC Spring), IEEE , 2016, s. 1-5Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider network-based positioning based on times series of proximity reports from a mobile device, either only a proximity indicator, or a vector of RSS from observed nodes. Such positioning corresponds to a latent and nonlinear observation model. To address these problems, we combine two powerful tools, namely particle filtering and Gaussian process regression (GPR) for radio signal propagation modeling. The latter also provides some insights into the spatial correlation of the radio propagation in the considered area. Radio propagation modeling and positioning performance are evaluated in a typical office area with Bluetooth-Low-Energy (BLE) beacons deployed for proximity detection and reports. Results show that the positioning accuracy can be improved by using GPR.

    sted, utgiver, år, opplag, sider
    IEEE, 2016
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-128255 (URN)10.1109/VTCSpring.2016.7504255 (DOI)000386528400206 ()9781509016983 (ISBN)
    Konferanse
    2016 IEEE 83rd Vehicular Technology Conference: VTC2016-Spring, 15–18 May 2016, Nanjing, China
    Tilgjengelig fra: 2016-05-24 Laget: 2016-05-24 Sist oppdatert: 2019-02-12bibliografisk kontrollert
    3. Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data
    Åpne denne publikasjonen i ny fane eller vindu >>Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data
    Vise andre…
    2016 (engelsk)Inngår i: 19th International Conference on  Information Fusion (FUSION), 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 1461-1468Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Kernel-based machine learning methods are gaining increasing interest in flow modeling and prediction in recent years. Gaussian process (GP) is one example of such kernelbased methods, which can provide very good performance for nonlinear problems. In this work, we apply GP regression to flow modeling and prediction of athletes in ski races, but the proposed framework can be generally applied to other use cases with device trajectories of positioned data. Some specific aspects can be addressed when the data is periodic, like in sports where the event is split up over multiple laps along a specific track. Flow models of both the individual skier and a cluster of skiers are derived and analyzed. Performance has been evaluated using data from the Falun Nordic World Ski Championships 2015, in particular the Men’s cross country 4 × 10 km relay. The results show that the flow models vary spatially for different skiers and clusters. We further demonstrate that GP regression provides powerful and accurate models for flow prediction.

    sted, utgiver, år, opplag, sider
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-129758 (URN)9780996452748 (ISBN)9781509020126 (ISBN)
    Konferanse
    19th International Conference on Information Fusion, 5-8 July 2016, Heidelberg, Germany
    Tilgjengelig fra: 2016-06-27 Laget: 2016-06-27 Sist oppdatert: 2019-02-12bibliografisk kontrollert
    Fulltekst (pdf)
    Position Estimation in Uncertain Radio Environments and Trajectory Learning
    Download (pdf)
    omslag
    Download (jpg)
    presentationsbild
  • 2773.
    Zhao, Yuxin
    et al.
    Ericsson AB, Sweden.
    Yin, Feng
    Ericsson AB, Sweden.
    Gunnarsson, Fredrik
    Ericsson AB, Sweden.
    Hultkratz, Fredrik
    Ericsson AB, Sweden.
    Fagerlind, Johan
    Ericsson AB, Sweden.
    Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data2016Inngår i: 19th International Conference on  Information Fusion (FUSION), 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 1461-1468Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Kernel-based machine learning methods are gaining increasing interest in flow modeling and prediction in recent years. Gaussian process (GP) is one example of such kernelbased methods, which can provide very good performance for nonlinear problems. In this work, we apply GP regression to flow modeling and prediction of athletes in ski races, but the proposed framework can be generally applied to other use cases with device trajectories of positioned data. Some specific aspects can be addressed when the data is periodic, like in sports where the event is split up over multiple laps along a specific track. Flow models of both the individual skier and a cluster of skiers are derived and analyzed. Performance has been evaluated using data from the Falun Nordic World Ski Championships 2015, in particular the Men’s cross country 4 × 10 km relay. The results show that the flow models vary spatially for different skiers and clusters. We further demonstrate that GP regression provides powerful and accurate models for flow prediction.

    Fulltekst (pdf)
    Fusion 2016
  • 2774.
    Zhendong, Wang
    Linköpings universitet, Institutionen för datavetenskap, Statistik och maskininlärning. Linköpings universitet, Filosofiska fakulteten.
    Error Pattern Recognition Using Machine Learning2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Mobile networks use automated continuous integration to secure the new technologies, which must reach high quality and backwards compatibility. The machinery needs to be constantly improved to meet the high demands that exist today and will evolve in the future. When testing products in large scale in a telecommunication environment, many parameters may be causing the error. Machine learning can help to assign troubleshooting labels and identify problematic areas in the test environment.

    In this thesis project, different modeling approaches will be applied step-wise. First, both the TF-IDF (term frequency-inverse document frequency) method and Topic model- ing will be applied for constructing variables. Since the TF-IDF method generates high dimensional variables in this case, Principal component analysis (PCA) is considered as a regularization method to reduce the dimensions. The results of this part will be evaluated by using different criteria.

    After the variable construction, two semi-supervised models called Label propagation and Label spreading will be applied for the purpose of assigning troubleshooting labels. In both algorithms, one weight matrix for measuring the similarities between different cases needs to be constructed. Two different methods for building up the weight matrix will be tested separately: Gaussian kernel and the nearest-neighbor method.

    Different hyperparameters in these two algorithms will be experimented with, to select the one which will return the optimal results. After the optimal model is selected, the unlabeled data will be divided up in different proportions for fitting the model. This is to test if the proportions of unlabeled data will affect the result of semi-supervised learning in our case. The classification results from the modeling part will be examined using three classical measures: accuracy, precision and recall. In addition, random permutations cross- validation is applied for the evaluation.

    Fulltekst (pdf)
    Error Pattern Recognition Using Machine Learning
  • 2775.
    Zhu, Yurong
    Linköpings universitet, Matematiska institutionen, Matematisk statistik. Linköpings universitet, Tekniska fakulteten.
    Large Deviations on Longest Runs2016Student paper other, 10 poäng / 15 hpOppgave
    Abstract [en]

    The study on the longest stretch of consecutive successes in \random" trials dates back to 1916 when the German philosopher Karl Marbe wrote a paper concerning the longest stretch of consecutive births of children of the same sex as appearing in the birth register of a Bavarian town. The result was actually used by parents to \predict" the sex of their children. The longest stretch of same-sex births during that time in 200 thousand birth registrations was actually 17 t log2(200 103): During the past century, the research of longest stretch of consecutive successes (longest runs) has found applications in various areas, especially in the theory of reliability. The aim of this thesis is to study large deviations on longest runs in the setting of Markov chains. More precisely, we establish a general large deviation principle for the longest success run in a two-state (success or failure) Markov chain. Our tool is based on a recent result regarding a general large deviation for the longest success run in Bernoulli trails. It turns out that the main ingredient in the proof is to implement several global and local estimates of the cumulative distribution function of the longest success run.

    Fulltekst (pdf)
    Large Deviations on Longest Runs
  • 2776. Bestill onlineKjøp publikasjonen >>
    Zikrin, Spartak
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska högskolan.
    Large-Scale Optimization Methods with Application to Design of Filter Networks2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Nowadays, large-scale optimization problems are among those most challenging. Any progress in developing methods for large-scale optimization results in solving important applied problems more effectively. Limited memory methods and trust-region methods represent two ecient approaches used for solving unconstrained optimization problems. A straightforward combination of them deteriorates the efficiency of the former approach, especially in the case of large-scale problems. For this reason, the limited memory methods are usually combined with a line search. We develop new limited memory trust-region algorithms for large-scale unconstrained optimization. They are competitive with the traditional limited memory line-search algorithms.

    In this thesis, we consider applied optimization problems originating from the design of lter networks. Filter networks represent an ecient tool in medical image processing. It is based on replacing a set of dense multidimensional lters by a network of smaller sparse lters called sub-filters. This allows for improving image processing time, while maintaining image quality and the robustness of image processing.

    Design of lter networks is a nontrivial procedure that involves three steps: 1) choosing the network structure, 2) choosing the sparsity pattern of each sub-filter and 3) optimizing the nonzero coecient values. So far, steps 1 and 2 were mainly based on the individual expertise of network designers and their intuition. Given a sparsity pattern, the choice of the coecients at stage 3 is related to solving a weighted nonlinear least-squares problem. Even in the case of sequentially connected lters, the resulting problem is of a multilinear least-squares (MLLS) type, which is a non-convex large-scale optimization problem. This is a very dicult global optimization problem that may have a large number of local minima, and each of them is singular and non-isolated. It is characterized by a large number of decision variables, especially for 3D and 4D lters.

    We develop an effective global optimization approach to solving the MLLS problem that reduces signicantly the computational time. Furthermore, we  develop efficient methods for optimizing sparsity of individual sub-filters  in lter networks of a more general structure. This approach offers practitioners a means of nding a proper trade-o between the image processing quality and time. It allows also for improving the network structure, which makes automated some stages of designing lter networks.

    Delarbeid
    1. On Efficiently Combining Limited Memory and Trust-Region Techniques
    Åpne denne publikasjonen i ny fane eller vindu >>On Efficiently Combining Limited Memory and Trust-Region Techniques
    2013 (engelsk)Rapport (Annet vitenskapelig)
    Abstract [en]

    Limited memory quasi-Newton methods and trust-region methods represent two efficient approaches used for solving unconstrained optimization problems. A straightforward combination of them deteriorates the efficiency of the former approach, especially in the case of large-scale problems. For this reason, the limited memory methods are usually combined with a line search. We show how to efficiently combine limited memory and trust-region techniques. One of our approaches is based on the eigenvalue decomposition of the limited memory quasi-Newton approximation of the Hessian matrix. The decomposition allows for finding a nearly-exact solution to the trust-region subproblem defined by the Euclidean norm with an insignificant computational overhead compared with the cost of computing the quasi-Newton direction in line-search limited memory methods. The other approach is based on two new eigenvalue-based norms. The advantage of the new norms is that the trust-region subproblem is separable and each of the smaller subproblems is easy to solve. We show that our eigenvalue-based limited-memory trust-region methods are globally convergent. Moreover, we propose improved versions of the existing limited-memory trust-region algorithms. The presented results of numerical experiments demonstrate the efficiency of our approach which is competitive with line-search versions of the L-BFGS method.

    sted, utgiver, år, opplag, sider
    Linköping: Linköping University Electronic Press, 2013. s. 33
    Serie
    LiTH-MAT-R, ISSN 0348-2960 ; 2013:13
    Emneord
    Unconstrained Optimization; Large-scale Problems; Limited Memory Methods;
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-102005 (URN)LiTH-MAT-R--2013/13--SE (ISRN)
    Tilgjengelig fra: 2013-11-26 Laget: 2013-11-26 Sist oppdatert: 2016-01-12bibliografisk kontrollert
    2. Global search strategies for solving multilinear least-squares problems
    Åpne denne publikasjonen i ny fane eller vindu >>Global search strategies for solving multilinear least-squares problems
    2012 (engelsk)Inngår i: Sultan Qaboos University Journal for Science, ISSN 1027-524X, Vol. 17, nr 1, s. 12-21Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The multilinear least-squares (MLLS) problem is an extension of the linear leastsquares problem. The difference is that a multilinear operator is used in place of a matrix-vector product. The MLLS is typically a large-scale problem characterized by a large number of local minimizers. It originates, for instance, from the design of filter networks. We present a global search strategy that allows for moving from one local minimizer to a better one. The efficiency of this strategy is illustrated by results of numerical experiments performed for some problems related to the design of filter networks.

    sted, utgiver, år, opplag, sider
    Sultan Qaboos University, 2012
    Emneord
    Global optimization; Global search strategies; Multilinear least-squares; Filter
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-78918 (URN)
    Tilgjengelig fra: 2012-08-28 Laget: 2012-06-25 Sist oppdatert: 2015-09-03bibliografisk kontrollert
    3. Sparsity Optimization in Design of Multidimensional Filter Networks
    Åpne denne publikasjonen i ny fane eller vindu >>Sparsity Optimization in Design of Multidimensional Filter Networks
    2013 (engelsk)Rapport (Annet vitenskapelig)
    Abstract [en]

    Filter networks is a powerful tool used for reducing the image processing time, while maintaining its reasonably high quality.They are composed of sparse sub-filters whose low sparsity ensures fast image processing.The filter network design is related to solvinga sparse optimization problem where a cardinality constraint bounds above the sparsity level.In the case of sequentially connected sub-filters, which is the simplest network structure of those considered in this paper, a cardinality-constrained multilinear least-squares (MLLS) problem is to be solved. If to disregard the cardinality constraint, the MLLS is typically a large-scale problem characterized by a large number of local minimizers. Each of the local minimizers is singular and non-isolated.The cardinality constraint makes the problem even more difficult to solve.An approach for approximately solving the cardinality-constrained MLLS problem is presented.It is then applied to solving a bi-criteria optimization problem in which both thetime and quality of image processing are optimized. The developed approach is extended to designing filter networks of a more general structure. Its efficiency is demonstrated by designing certain 2D and 3D filter networks. It is also compared with the existing approaches.

    sted, utgiver, år, opplag, sider
    Linköping: Linköping University Electronic Press, 2013. s. 21
    Serie
    LiTH-MAT-R, ISSN 0348-2960 ; 2013:16
    Emneord
    Sparse optimization; Cardinality Constraint; Multicriteria Optimization; Multilinear Least-Squares Problem; Filter networks; Medical imaging
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-103915 (URN)LiTH-MAT-R-2013/16-SE (ISRN)
    Tilgjengelig fra: 2014-02-03 Laget: 2014-02-03 Sist oppdatert: 2016-11-24bibliografisk kontrollert
    Fulltekst (pdf)
    Large-Scale Optimization Methods with Application to Design of Filter Networks
    Download (pdf)
    omslag
  • 2777.
    Zografos, Vasileios
    et al.
    University College London.
    Buxton, Bernard
    University College London.
    Affine Invariant, Model-Based Object Recognition Using Robust Metrics and Bayesian Statistics2005Inngår i: Proceedings of the International Conference on Image Analysis and Recognition, Berlin: Springer , 2005, s. 407-414Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    FULLTEXT02
  • 2778.
    Zografos, Vasileios
    et al.
    Universty College London.
    Buxton, Bernard
    Universty College London.
    Evaluation of linear combination of views for object recognition: Chapter 52007Inngår i: ADVANCES IN INTELLIGENT INFORMATION PROCESSING: Tools and Applications / [ed] B. Chanda and C. A. Murthy, World Scientific Publishing Company , 2007, s. 85-106Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    In this work, we present a method for model-based recognition of 3d objects from a small number of 2d intensity images taken from nearby, but otherwise arbitrary viewpoints. Our method works by linearly combining images from two (or more) viewpoints of a 3d object to synthesise novel views of the object. The object is recognised in a target image by matching to such a synthesised, novel view. All that is required is the recovery of the linear combination parameters, and since we are working directly with pixel intensities, we suggest searching the parameter space using a global, evolutionary optimisation algorithm combined with a local search method in order efficiently to recover the optimal parameters and thus recognise the object in the scene. We have experimented with both synthetic data and real-image, public databases.

  • 2779.
    Zorina, I. A.
    et al.
    Volgograd State University, Russia.
    Tkachev, Vladimir
    Volgograd State University, Russia.
    On entire solutions of quasilinear equations with a quadratic principal part2008Inngår i: Vestn. Samar. Gos. Univ. Estestvennonauchn. Ser., ISSN 1810-5378, s. 108-123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We establish the existence of a countable family of entire solutions for a class of quasilinear equations including Simon's equation. In particular, we show that all obtained solutions have a polynomial growth and their topological structure is similar to that of harmonic polynomials.

  • 2780.
    Äng, Oscar
    et al.
    Linköpings universitet, Matematiska institutionen. Linköpings universitet, Tekniska fakulteten.
    Trygg, Alexander
    Linköpings universitet, Matematiska institutionen. Linköpings universitet, Tekniska fakulteten.
    Planering av stränggjutningsproduktion: En heruistisk metod2017Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Detta arbete syftar till att undersöka om det är möjligt att med en heuristisk metod skapa giltiga lösningar till ett problem vid planering av stränggjutningsproduktion på SSAB. Planeringsproblemet uppstår när stål av olika sorter ska gjutas under samma dag. Beroende på i vilken ordning olika kundordrar av stål gjuts uppstår spill av olika storlek. Detta spill ska minimeras och tidigare arbete har genomförts på detta problem och resulterat i en matematisk modell för att skapa lösningar till problemet. Det tar i praktiken lång tid att hitta bra lösningar med modellen och frågeställningen är om det går att göra detta med en heuristisk metod för att kunna generera bra lösningar snabbare.

    Med inspiration från Variable Neighbourhood Search, Simulated Annealing och tabusökning har heuristiker skapats, implementerats och utvärderats mot den matematiska modellen. En av heuristikerna presterar bättre än den matematiska modellen gör på 10 minuter. Matematiska modellens resultat efter 60 minuter körtid är bättre än den utvecklade heuristiken, men resultaten är nära varandra. Körtiden för heuristiken tar signifikant mindre tid än 10 minuter.

    Fulltekst (pdf)
    fulltext
  • 2781.
    Åberg, Johnny
    Linköpings universitet, Matematiska institutionen. Linköpings universitet, Tekniska fakulteten.
    Programmering i Ma1c: ett specialanpassat utbildningsmaterial för lösning av sannolikhetsproblem2019Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Från den 1 juli 2018 ingår matematisk problemlösning med programmering i ämnet matematik på gymnasieskolans teknik- och naturvetenskapsprogram. Den här studien utgår från den nya kursplanen för Matematik 1c (Ma1c), försöker göra en rimlig tolkning av Skolverkets skrivningar, presenterar ett specialanpassat utbildningsmaterial avsett för kursens programmeringsdel och beskriver hur materialet har utarbetats. Materialet består av en projektorpresentation och ett elevhäfte med övningsuppgifter, fokuserar på sannolikhetsproblemen i Ma1c, är provat i tre mindre och osystematiska pilotförsök, är inte helt utprovat och behöver förbättras ytterligare. Givet studiens tolkning, och 9 timmar undervisning i programmering, finns det goda skäl att misstänka att eleverna inte kommer att hinna lära sig matematisk problemlösning med programmering i Ma1c.

    Fulltekst (pdf)
    fulltext
  • 2782.
    Åkesson, Lisa
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Statistik.
    Henningsson, Denise
    Linköpings universitet, Institutionen för datavetenskap, Statistik.
    Klassificering av köp på betalda sökannonser2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Datakonsultföretaget Knowit AB har en kund som annonserar på Google AdWords. Denna uppsats fokuserar huvudsakligen på att hitta de olika inställningarna i AdWords som genererar köp av kundens produkt. Om en inställning ofta genererar klick men sällan köp av produkten är den inställningen inte lönsam.Responsvariabeln i denna uppsats är binär och indikerar på om ett klick på annonsen lett till köp av produkten eller inte. Eftersom responsvariabelns fördelning var skev har samplingstekniken SMOTE använts för att skapa fler observationer i minoritetsklassen. De statistiska metoder som använts och presenterats i uppsatsen är logistisk regression, neurala nätverk och beslutsträd.Resultatet gav att de fyra undersökta inställningarna påverkar sannolikheten för köp. Den första inställningen resulterade i att om dator används vid sökning på Google är sannolikheten att ett klick leder till köp betydligt högre än för mobil och surfplatta. Den andra inställningen resulterar i att en ”exakt matchning” för sökordet ger högst sannolikhet till köp och ”bred matchning” ger lägst sannolikhet. Den tredje inställningen visar att vilken veckodag annonsen klickas på påverkar sannolikheten för köp. På söndag är sannolikheten högst att ett klick leder till köp, och de två dagar som har lägst sannolikhet är lördag och tisdag. Slutligen har det undersökts om annonsens genomsnittsposition påverkar sannolikheten att produkten köps. Resultatet som gavs är att ju högre värde på genomsnittsposition, desto högre blir sannolikheten för köp.

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    fulltext
  • 2783.
    Ålund, Oskar
    et al.
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    Iaccarino, Gianluca
    Department of Mechanical Engineering and Institute for Computational Mathematical Engineering, Stanford University, Stanford, California, USA.
    Nordström, Jan
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    Learning to Differentiate2020Rapport (Annet vitenskapelig)
    Abstract [en]

    Artificial neural networks together with associated computational libraries provide a powerful framework for constructing both classification and regression algorithms. In this paper we use neural networks to design linear and non-linear discrete differential operators. We show that neural network based operators can be used to construct stable discretizations of initial boundary-value problems by ensuring that the operators satisfy a discrete analogue of integration-byparts known as summation-by-parts. Furthermore we demonstrate the benefits of building the summation-by-parts property into the network by weight restriction, rather than enforcing it through a regularizer. We conclude that, if possible, known structural elements of an operation are best implemented as innate—rather than learned—properties of the network. The strategy developed in this work also opens the door for constructing stable differential operators on general meshes.

    Fulltekst (pdf)
    Learning to Differentiate
  • 2784.
    Ålund, Oskar
    et al.
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    Nordström, Jan
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    A provably stable, non-iterative domain decomposition technique for the advection-diffusion equation2016Rapport (Annet vitenskapelig)
    Abstract [en]

    We describe an efficient, non-iterative domain decomposition approach for the onedimensional advection–diffusion equation based on the Summation-by-Parts technique in both time and space. A fully discrete multidomain analogue of the continuous equation is formulated and a linear system consisting only of the solution components involved in the coupling between the subdomain interfaces is isolated. Once the coupling system is solved, the full solution is found by computing linear combinations of known vectors, weighted by the coupling components. Both stability and invertibility of the discrete scheme is proved using standard Summation-by-Parts procedures.

    In a numerical study we show that perfunctory implementations of monodomain Summation-by-Parts based time integration can be improved upon significantly. Using our proposed method we are able to reduce execution time and memory footprint by up to 80% and 95% respectively. Similar improvements in execution time is shown also when compared against explicit Runge–Kutta time integration.

    Fulltekst (pdf)
    Provably Stable, Non-iterative Domain Decomposition Technique for the Advection-Diffusion Equation
  • 2785.
    Ålund, Oskar
    et al.
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    Nordström, Jan
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    A Stable Domain Decomposition Technique for Advection–Diffusion Problems2018Inngår i: Journal of Scientific Computing, ISSN 0885-7474, E-ISSN 1573-7691, Vol. 77, nr 2, s. 755-774Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of implicit methods for numerical time integration typically generates very large systems of equations, often too large to fit in memory. To address this it is necessary to investigate ways to reduce the sizes of the involved linear systems. We describe a domain decomposition approach for the advection–diffusion equation, based on the Summation-by-Parts technique in both time and space. The domain is partitioned into non-overlapping subdomains. A linear system consisting only of interface components is isolated by solving independent subdomain-sized problems. The full solution is then computed in terms of the interface components. The Summation-by-Parts technique provides a solid theoretical framework in which we can mimic the continuous energy method, allowing us to prove both stability and invertibility of the scheme. In a numerical study we show that single-domain implementations of Summation-by-Parts based time integration can be improved upon significantly. Using our proposed method we are able to compute solutions for grid resolutions that cannot be handled efficiently using a single-domain formulation. An order of magnitude speed-up is observed, both compared to a single-domain formulation and to explicit Runge–Kutta time integration.

    Fulltekst (pdf)
    fulltext
  • 2786.
    Ålund, Oskar
    et al.
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    Nordström, Jan
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    A stable, high order accurate and efficient hybrid method for flow calculations in complex geometries2018Inngår i: 2018 AIAA Aerospace Sciences Meeting, AIAA SciTech Forum, (AIAA 2018-1096), American Institute of Aeronautics and Astronautics, 2018, nr 210059, s. 1-9Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The suitability of a discretization method is highly dependent on the shape of the domain. Finite difference schemes are typically efficient, but struggle with complex geometry, while finite element methods are expensive but well suited for complex geometries. In this paper we propose a provably stable hybrid method for a 2D advection–diffusion problem, using a class of inner product compatible projection operators to couple the non-conforming grids that arise due to varying the discretization method throughout the domain.

    Fulltekst (pdf)
    A stable, high order accurate and efficient hybrid method for flow calculations in complex geometries
  • 2787.
    Ålund, Oskar
    et al.
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    Nordström, Jan
    Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
    Encapsulated high order difference operators on curvilinear non-conforming grids2019Inngår i: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 385, s. 209-224Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Constructing stable difference schemes on complex geometries is an arduous task. Even fairly simple partial differential equations end up very convoluted in their discretized form, making them difficult to implement and manage. Spatial discretizations using so called summation-by-parts operators have mitigated this issue to some extent, particularly on rectangular domains, making it possible to formulate stable discretizations in a compact and understandable manner. However, the simplicity of these formulations is lost for curvilinear grids, where the standard procedure is to transform the grid to a rectangular one, and change the structure of the original equation. In this paper we reinterpret the grid transformation as a transformation of the summation-by-parts operators. This results in operators acting directly on the curvilinear grid. Together with previous developments in the field of nonconforming grid couplings we can formulate simple, implementable, and provably stable schemes on general nonconforming curvilinear grids. The theory is applicable to methods on summation-by-parts form, including finite differences, discontinuous Galerkin spectral element, finite volume, and flux reconstruction methods. Time dependent advection–diffusion simulations corroborate the theoretical development.

    Fulltekst tilgjengelig fra 2021-02-26 12:23
  • 2788.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Asymptotic analysis of a mixed boundary value problem in a multi-structure2003Rapport (Annet vitenskapelig)
  • 2789.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Asymptotic analysis of a transmission problem in a multi-structure2003Rapport (Annet vitenskapelig)
  • 2790.
    Åslund, Jan
    Linköpings universitet, Matematiska institutionen. Linköpings universitet, Tekniska högskolan.
    Asymptotic analysis of junctions in multi-structures2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A multi-structure is a compound domain that consists of several substructures such as solid bodies, thin shells and slender rods. In this thesis we consider different mixed boundary value problems in multi-structures. In the formulations of these problems a small perturbation parameter c is introduced, e.g., the thickness of a shell. The common objective of the papers in this thesis is to analyse the junctions between the substructures and to construct the asymptotics of the solution as ε tends to zero.

  • 2791.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Modellbaserad diagnos och överbestämda system2004Inngår i: Workshop i tillämpad matematik,2004, 2004Konferansepaper (Annet vitenskapelig)
  • 2792. Bestill onlineKjøp publikasjonen >>
    Åström, Freddie
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Tekniska högskolan.
    Variational Tensor-Based Models for Image Diffusion in Non-Linear Domains2015Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This dissertation addresses the problem of adaptive image filtering.

    Although the topic has a long history in the image processing community, researchers continuously present novel methods to obtain ever better image restoration results.

    With an expanding market for individuals who wish to share their everyday life on social media, imaging techniques such as compact cameras and smart phones are important factors. Naturally, every producer of imaging equipment desires to exploit cheap camera components while supplying high quality images. One step in this pipeline is to use sophisticated imaging software including, e.g., noise reduction to reduce manufacturing costs, while maintaining image quality.

    This thesis is based on traditional formulations such as isotropic and tensor-based anisotropic diffusion for image denoising. The difference from main-stream denoising methods is that this thesis explores the effects of introducing contextual information as prior knowledge for image denoising into the filtering schemes. To achieve this, the adaptive filtering theory is formulated from an energy minimization standpoint. The core contributions of this work is the introduction of a novel tensor-based functional which unifies and generalises standard diffusion methods. Additionally, the explicit Euler-Lagrange equation is derived which, if solved, yield the stationary point for the minimization problem. Several aspects of the functional are presented in detail which include, but are not limited to, tensor symmetry constraints and convexity. Also, the classical problem of finding a variational formulation to a given tensor-based partial differential equation is studied.

    The presented framework is applied in problem formulation that includes non-linear domain transformation, e.g., visualization of medical images.

    Additionally, the framework is also used to exploit locally estimated probability density functions or the channel representation to drive the filtering process.

    Furthermore, one of the first truly tensor-based formulations of total variation is presented. The key to the formulation is the gradient energy tensor, which does not require spatial regularization of its tensor components. It is shown empirically in several computer vision applications, such as corner detection and optical flow, that the gradient energy tensor is a viable replacement for the commonly used structure tensor. Moreover, the gradient energy tensor is used in the traditional tensor-based anisotropic diffusion scheme. This approach results in significant improvements in computational speed when the scheme is implemented on a graphical processing unit compared to using the commonly used structure tensor.

    Fulltekst (pdf)
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    Download (jpg)
    presentationsbild
  • 2793.
    Österberg, Sofia
    Linköpings universitet, Matematiska institutionen, Matematik och tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Motiverad för matematik?: En litteraturstudie om yttre och inre faktorers påverkan på gymnasieelevers motivation i skolmatematik2014Independent thesis Advanced level (degree of Master (Two Years)), 10 poäng / 15 hpOppgave
    Abstract [sv]

    När jag har varit ute i gymnasieskolan på praktik har jag mött elever med väldigt olika attityder och inställningar till matematik. Dessa attityder kan ha följt med eleverna länge, då de möter matematiken för första gången i förskolan. När eleverna sedan når gymnasiet är de olika motiverade för att lära sig matematik och som lärare kan det vara svårt att veta hur man ska motivera sina elever till att lära sig matematik. Syftet med denna litteraturstudie är att sammanställa och analysera vilka yttre- och intre faktorer som påverkar elevers motivation i ämnet matematik, för att sedan kunna diskutera vad dessa faktorer kan ha för inverkan på elever motivation på gymnasiet.

    Litteraturstudien visar att det finns flertalet yttre- och inre faktorer som kan påverka elevers motivation för att lära sig matematik under skolgången och att det finns olika teorier om när elevers motivation för att lära sig matematik sjunker. Dessa faktorer har olika stor påverkan på elevernas motivation på gymnasiet och de flesta av faktorerna kommer att kunna påverka eleverna även när de går på gymnasiet. Utifrån varje faktor framgår det hur det påverkar eleverna och därför också vad man som lärare kan göra för att höja elevernas motivation för att lära sig ämnet matematik.

    Fulltekst (pdf)
    Motiverad för matematik?
  • 2794.
    Österholm, Magnus
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    A metacognitive perspective on reading mathe-matical texts: Students’ beliefs and criteria for comprehension2006Manuskript (preprint) (Annet vitenskapelig)
  • 2795.
    Österholm, Magnus
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    A reading comprehension perspective on problem solving2006Inngår i: Developing and researching quality in mathematics teaching and learning : proceedings of MADIF 5 : the 5th Swedish Mathematics Education Research Seminar, Malmö, January 24-25, 2006 / [ed] Christer Bergsten and Barbro Grevholm, Linköping: Svensk förening för matematikdidaktisk forskning (SMDF) , 2006, s. 136-145Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The purpose of this paper is to discuss the bi-directional relationship between reading comprehension and problem solving, i.e. how reading comprehension can affect and become an integral part of problem solving, and how it can be affected by the mathematical text content or by the mathematical situation when the text is read. Based on theories of reading comprehension and a literature review it is found that the relationship under study is complex and that the reading process can affect as well as act as an integral part of the problem solving process but also that not much research has focused on this relationship.

    Fulltekst (pdf)
    fulltext
  • 2796.
    Österholm, Magnus
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Characterizing reading comprehension of mathematical texts2006Inngår i: Educational Studies in Mathematics, ISSN 0013-1954, E-ISSN 1573-0816, Vol. 63, nr 3, s. 325-346Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study compares reading comprehension of three different texts: two mathematical texts and one historical text. The two mathematical texts both present basic concepts of group theory, but one does it using mathematical symbols and the other only uses natural language. A total of 95 upper secondary and university students read one of the mathematical texts and the historical text. Before reading the texts, a test of prior knowledge for both mathematics and history was given and after reading each text, a test of reading comprehension was given. The results reveal a similarity in reading comprehension between the mathematical text without symbols and the historical text, and also a difference in reading comprehension between the two mathematical texts. This result suggests that mathematics in itself is not the most dominant aspect affecting the reading comprehension process, but the use of symbols in the text is a more relevant factor. Although the university students had studied more mathematics courses than the upper secondary students, there was only a small and insignificant difference between these groups regarding reading comprehension of the mathematical text with symbols. This finding suggests that there is a need for more explicit teaching of reading comprehension for texts including symbols.

    Fulltekst (pdf)
    fulltext
  • 2797.
    Österholm, Magnus
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Epistemological beliefs and communication in mathematics education at upper secondary and university levels2009Inngår i: Perspectives on mathematical knowledge. Proceedings of MADIF 6, the 6th Swedish Mathematics Education Research Seminar, Stockholm, January 29-30, 2008 / [ed] Christer Bergsten, Barbro Grevholm, Thomas Lingefjärd, Linköping: Svensk förening för matematikdidaktisk forskning (SMDF) , 2009, s. 132-134Konferansepaper (Annet vitenskapelig)
  • 2798.
    Österholm, Magnus
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Learning mathematics by reading - a study of students interacting with a text2003Rapport (Annet vitenskapelig)
    Abstract [en]

    This study investigates the situation when students on their own read a new mathematical text, and solve problems relevant to the text. The students worked together in pairs on a given text, about the absolute value of real numbers, with a video camera recording their activity. First, the students were instructed to read and discuss the text without any given tasks. Thereafter, the students were given exercises relevant to the text, and they were allowed to keep the text and use it when working with these exercises. Two pairs of students participated, all of them on their last year on the natural science programme at the Swedish upper secondary school. The observations reveal a variety of different activities among the students, and some questions also arise that would be interesting to examine in more detail.

    Fulltekst (pdf)
    fulltext
  • 2799.
    Österholm, Magnus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Matematiska institutionen, Tillämpad matematik.
    Learning mathematics by reading - a study of students interacting with a text2003Inngår i: Nordic pre-conference to ICME 10, 2003Konferansepaper (Annet vitenskapelig)
  • 2800. Bestill onlineKjøp publikasjonen >>
    Österholm, Magnus
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Läsa matematiska texter: Förståelse och lärande i läsprocessen2004Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [sv]

    Denna avhandling behandlar läsning av matematiska texter; hur och vad man förstår och lär sig vid läsningen. Fokus ligger på läsprocessen, det vill säga själva läsandet av texten och vad man förstår efter att läst igenom texten. Huvudsyftet är att studera specifika aspekter i läsandet av just matematiska texter för att testa och utveckla en befintlig, allmän teori kring läsprocessen. Speciellt studeras användningen av symboler i matematiska texter och hur detta kan påverka läsprocessen. Avhandlingen byggs upp av teoretiska diskussioner kring läsning av matematiska texter samt en empirisk studie bland gymnasieelever och universitetsstuderande.

    De teoretiska diskussionerna utgår bland annat från en litteraturstudie kring förekommande påståenden om speciella egenskaper hos matematiska texter, och speciellt diskuteras läsning av symboler och algebraiska uttryck.

    Den empiriska studien (med 106 deltagare) använde tre olika texter; en historietext om ryska revolutionen samt två matematiktexter om gruppteori. Matematiktexterna behandlar samma sak som gruppteori, men skillnaden mellan dem är att den ena använder matematiska symboler i sin presentation medan den andra inte alls använder symboler. Varje deltagare fick läsa en utav matematiktexterna samt historietexterna, och fick efter varje text besvara frågor om textens innehåll.

    Den grupp av personer som läste matematiktexten utan symboler har bättre resultat på frågor om texten än den grupp som läste texten med symboler. Detta verkar kunna bero på oförmåga att artikulera symboler vid läsning av texten samt att avkodningsförmågan inte verkar kunna utnyttjas på samma sätt för texten med symboler. Läsning av matematiska texter med symboler är alltså ganska speciellt och man kan behöva lära sig hur man läser sådana texter. Däremot verkar det finnas många likheter med läsning av matematiska texter utan symboler och historietexten. Det matematiska innehållet verkar alltså inte i någon större omfattning påverka läsprocessen, utan hur detta innehåll presenteras är en viktig aspekt.

    I de teoretiska diskussionerna ges förslag på hur läsning av matematiska symboler kan infogas i den allmänna teorin för läsprocessen. Överlag finns dock ingen anledning att se läsning av matematiska texter som någon speciell typ av process som skiljer sig från läsning av andra texter. Den allmänna teorin för läsprocessen kan därmed fungera som teoretisk grund även för läsförståelse av matematiska texter, möjligen med föreslaget tillägg om matematiska symboler.

    Fulltekst (pdf)
    FULLTEXT01
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