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  • 101.
    Eriksson, Kimmo
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Sjöstrand, Jonas
    Mälardalen University, Department of Mathematics and Physics.
    Strimling, Pontus
    Mälardalen University, Department of Mathematics and Physics.
    Optimal Expected Rank in a Two-Sided Secretary Problem2007In: Operations Research, ISSN 0030-364X, Vol. 55, no 5, p. 921-931Article in journal (Refereed)
    Abstract [en]

    In a two-sided version of the famous secretary problem, employers search for a secretary at the same time as secretaries search for an employer. Nobody accepts being put on hold, and nobody is willing to take part in more than N interviews. Preferences are independent, and agents seek to optimize the expected rank of the partner they obtain among the N potential partners. We find that in any subgame perfect equilibrium, the expected rank grows as the square root of N (whereas it tends to a constant in the original secretary problem). We also compute how much agents can gain by cooperation.

  • 102.
    Eriksson, Kimmo
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Sjöstrand, Jonas
    Mälardalen University, Department of Mathematics and Physics.
    Strimling, Pontus
    Mälardalen University, Department of Mathematics and Physics.
    Optimal stopping in a two-sided secretary problem2004Conference paper (Other academic)
  • 103.
    Eriksson, Kimmo
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Sjöstrand, Jonas
    KTH.
    Strimling, Pontus
    Mälardalen University, Department of Mathematics and Physics.
    Three-dimensional stable matching with cyclic preferences2006In: Mathematical Social Sciences, ISSN 0165-4896, E-ISSN 1879-3118, Vol. 52, no 1, p. 77-87Article in journal (Refereed)
    Abstract [en]

    We consider stable three-dimensional matchings of three genders (3GSM). Alkan [Alkan, A., 1988. Non-existence of stable threesome matchings. Mathematical Social Sciences 16, 207–209] showed that not all instances of 3GSM allow stable matchings. Boros et al. [Boros, E., Gurvich, V., Jaslar, S., Krasner, D., 2004. Stable matchings in three-sided systems with cyclic preferences. Discrete Mathematics 286, 1–10] showed that if preferences are cyclic, and the number of agents is limited to three of each gender, then a stable matching always exists. Here we extend this result to four agents of each gender. We also show that a number of well-known sufficient conditions for stability do not apply to cyclic 3GSM. Based on computer search, we formulate a conjecture on stability of “strongest link” 3GSM, which would imply stability of cyclic 3GSM.

  • 104.
    Eriksson, Lilly
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Welander, Jonas
    Mälardalen University, Department of Social Sciences.
    Granlund, Mats
    Mälardalen University, Department of Social Sciences.
    Elevers delaktighet i skolaktiviteter: En jämförelse av elever med och utan funktionshinder2006Conference paper (Refereed)
  • 105.
    Forssman, Ida
    Mälardalen University, Department of Mathematics and Physics.
    Matematik i förskolan.: Vilka faktorer är det som påverkar arbetssättet med matematik i förskolan.2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Syftet med arbetet är att undersöka varför det är viktigt med matematik och vilka faktorer det är som påverkar matematiken i förskolan enligt utvalda pedagoger samt författare. Undersökningen har gjorts genom fördjupning i litteratur inom området samt genom enkäter som har lämnats ut på två förskolor i en mellanstor kommun i Sverige. Resultaten har sedan sammanställts dels genom diagram samt skrift. Genom studien har det kommit fram att det är viktigt att redan i förskolan arbeta med matematik eftersom det förbereder barnen för skolan, en positiv syn på av matematik skapas och viktigast av allt för att det är viktigt för att man ska förenkla/klara sig i livet. De faktorer som påverkar arbetssättet med matematiken som har kommit fram genom denna studie är pedagogens förhållningsätt till matematik, utbildning/fortbildning, ekonomi, barnens ålder och intresse samt tiden.

  • 106.
    Fransson, C. -M
    et al.
    Chalmers University of Technology, Sweden.
    Lennartson, B.
    Chalmers University of Technology, Sweden.
    Wik, T.
    Chalmers University of Technology, Sweden.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    Saunders, M.
    Stanford University, Stanford, CA, United States.
    Gutman, P. -O
    Technion, Haifa, Israel.
    Global controller optimization using horowitz bounds2002In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2002, no 1, p. 247-252Conference paper (Refereed)
    Abstract [en]

    A procedure for global optimization of PID type controller parameters for SISO plants with model uncertainty is presented. Robustness to the uncertainties is guaranteed by the use of Horowitz bounds, which are used as constraints when low frequency performance is optimized. The basic idea of both the optimization and the parameter tuning is to formulate separate criteria for low, mid and high frequency closed loop properties. The trade-off between stability margins, high frequency robustness and low frequency performance is then elucidated and, hence, the final choice of parameters is facilitated. The optimization problems are non-convex and ill-conditioned and we use a combination of new global and standard local optimization algorithms available in the TOMLAB optimization environment to solve the problem. The method does not rely on a good initial guess and converges fast and robustly. It is applied to a controller structure comparison for a plant with an uncertain mechanical resonance. For a given control activity and stability margin as well as identical tuning parameters it is shown that a PID controller achieves slightly improved low frequency performance compared to an H∞ controller based on loop-shaping. The reason for this somewhat surprising result is the roll-off in the H∞ controller, which adds additional high frequency robustness compared to the PID controller. Computationally, a factor of 10-20 has been gained compared to an earlier, less general, version of the procedure. 

  • 107.
    Freivalds, R.
    et al.
    Latvian State Univ.
    Bonner, Richard
    Mälardalen University, Department of Mathematics and Physics.
    Quantum inductive inference by finite automata2008In: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 397, no 1-3, p. 70-76Article in journal (Refereed)
    Abstract [en]

    Freivalds and Smith [R. Freivalds, C.H. Smith Memory limited inductive inference machines, Springer Lecture Notes in Computer Science 621 (1992) 19-29] proved that probabilistic limited memory inductive inference machines can learn with probability 1 certain classes of total recursive functions, which cannot be learned by deterministic limited memory inductive inference machines. We introduce quantum limited memory inductive inference machines as quantum finite automata acting as inductive inference machines. These machines, we show, can learn classes of total recursive functions not learnable by any deterministic, nor even by probabilistic, limited memory inductive inference machines.

  • 108.
    Galili, Farida
    Mälardalen University, Department of Mathematics and Physics.
    Matematiksvårigher hos elever med invandrarbakgrund2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Syftet med uppsatsen är att försöka ta reda på om andraspråkselever har svårare med matematik på grund av att de inte behärskar språket eller om det finns andra orsaker till detta. Hur kan man förebygga och åtgärda detta och hur kan undervisningen anpassas till dessa elever?

    Mina frågeställningar är:

    • Har språket en stor betydelse i matematikundervisning?

    • Hur arbetar lärare respektive speciallärare med elever som har invandrarbakgrund i matematik?

    • Finns det andra orsakar till svårigheterna att förstå matematik?

    Jag har gjort intervjuer med tre lärare som alla har flerårig erfarenhet av att undervisa elever med invandrarbakgrund.

    Resultat visar att den stora svårigheten för de här eleverna, är bristen av språkförståelse och underliggande orsaker, som man bär med sig från sitt liv i ett krigshärjat land. Allt tillsammans skapar en brist på koncentration.

    Slutsatsen blir: För elever med invandrarbakgrund är det så viktigt att öka förståelsen och begreppsinlärningen att känna till vad ordet betyder ger en ingång till problemet. Bildens betydelse förstärker tänkandet tillsammans med ordets innebörd och bilden förstärker vi inlärningen.

  • 109.
    Gavel, Hillevi
    Mälardalen University, Department of Mathematics and Physics.
    A Collection of Games in Mathematics2005Licentiate thesis, comprehensive summary (Other scientific)
  • 110.
    Gavel, Hillevi
    Mälardalen University, Department of Mathematics and Physics.
    Patterns in Matrices Describing Permutation Orders2005Licentiate thesis, monograph (Other scientific)
  • 111.
    Gavel, Hillevi
    Mälardalen University, Department of Mathematics and Physics. Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Patterns in matrices describing permutation orders2004In: Proceedings of the 2nd Annual International Conference on Permutation Patterns PP'04 July 5-9, 2004 · Nanaimo, British Columbia, Canada, 2004Conference paper (Other academic)
  • 112.
    Gavel, Hillevi
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Strimling, Pontus
    Mälardalen University, Department of Mathematics and Physics.
    Nim with a modular Muller twist2004In: Integers, Vol. 4, p. G4-Article in journal (Refereed)
  • 113.
    Gustafsson, Peter
    Mälardalen University, Department of Mathematics and Physics.
    Gender inclusive physics education - a distance case2005In: European Journal of Physics, ISSN 0143-0807, Vol. 26, no 5, p. 843-849Article in journal (Refereed)
    Abstract [en]

    In earlier studies, it has been demonstrated that cooperative work has a positive influence on physics distance learning at university entrance level. In this paper, it is shown clearly that this teaching method in physics is advantageous for both genders. In fact, the collaboration seems to help male students more than female students to manage the course and to complete it. No difference was seen between the genders either in performance, measured in throughput (productivity) for the course, or in intrinsic motivation. Without cooperative work, the productivity for male students is far lower than for female students.

  • 114.
    Gustafsson, Peter
    Mälardalen University, Department of Mathematics and Physics.
    Improved method in distance teaching of physics2004In: European Journal of Physics, ISSN 0143-0807, Vol. 25, no 2, p. 185-191Article in journal (Refereed)
    Abstract [en]

    Results of introducing cooperative working methods on a distance learning course in physics are reported. This has increased the throughput of students in the course as measured in the number of ECTS points generated by the students. There is no significant indication that students more experienced in academic studies manage to complete the course more often than those with less experience. In student groups where the cooperative concept was fully realized a larger gain of knowledge was achieved, as measured by the force concept inventory test. Hence, it is important for the tutor to monitor activities in the groups by follow-up questions during the course and to stress the importance of all students participating actively.

  • 115.
    Gustafsson, Peter
    Mälardalen University, Department of Mathematics and Physics.
    Physics teaching at a distance2002In: European Journal of Physics, ISSN 0143-0807, Vol. 23, no 5, p. 469-474Article in journal (Refereed)
    Abstract [en]

    A subject such as physics which relies heavily on practical experiments is a challenge to teach in the form of a distance course. You must make choices as to whether the course includes experiments and if so on what level. With an objective that it is more important to establish concepts than to verify physical laws through precise measurements, it is possible for students to conduct experiments in their homes. Four years' experience of this kind of introductory physics course (mechanics and thermal physics) at distance is covered. The understanding of mechanical concepts as measured by the force concept inventory test shows that distance education does work in the subject of physics. The problem that some students do not complete their distance course is noted and it is suggested that this problem can be addressed by transforming established methods used in campus courses to encourage interactivity among students. A probable result of applying these methods would be an enhanced understanding of the concept of physics and problem-solving skills.

  • 116. Hagelin, N
    et al.
    Pramborg, B
    Stenberg, F
    Mälardalen University, Department of Mathematics and Physics.
    Hedge Fund Allocation under Higher Moments and Illiquidity2005In: HEDGE FUNDS: INSIGHTS IN PERFORMANCE MEASUREMENT, RISK ANALYSIS, AND PORTFOLIO ALLOCATION, John Wiley & Sons , 2005Chapter in book (Other academic)
    Abstract [en]

    We use the discrete-time dynamic investment model to evaluate the gains from including hedge funds in the investment opportunity set. In this multi-period framework, an investor's utility is affected by all moments of the return distribution. We assume that investors rebalance their portfolios on a monthly basis, and we compare the performance of portfolios which may include hedge funds versus portfolios consisting of stocks and bonds only. Our findings show that: (1) investors will allocate wealth to hedge funds even when they take into account deviations from normality in hedge fund returns. Those ex ante optimal allocations result in portfolios that ex post have higher geometric returns compared to the case in which hedge fund investing is not permitted; (2) investors that form portfolios taking all moments of the return distribution into account construct portfolios that are very similar to the portfolios being constructed by investors who care only about expected return and standard deviation, suggesting that the two first moments of the return distribution dominate higher moments; (3) the positive effect on capital growth from including hedge funds into the portfolios remains, although smaller, when the so-called "stale-pricing effect" is considered; and (4) lock-up periods and advance notice periods may force investors to have portfolios that deviate from their targeted ex ante optimal portfolios. Through a simple experiment we show that this inability to rebalance hedge fund allocations may seriously impact the benefits that hedge fund allocations appear to offer.

  • 117.
    Hagelin, N.
    et al.
    Stockholm University.
    Pramborg, B.
    Stockholm University.
    Stenberg, Fredrik
    Mälardalen University, Department of Mathematics and Physics.
    Gains from Adding Funds of Hedge Funds to Portfolios of Traditional Assets: An International Perspective2005In: FUNDS OF HEDGE FUNDS: Performance, Assessment, Diversification, and Statistical Properties, BUTTERWORTH HEINEMANN , 2005, p. 171-187Chapter in book (Other academic)
    Abstract [en]

    We investigate the certainty-equivalent wealth gain from adding funds of hedge funds to portfolios of traditional assets for investors in G7 countries. The allows us to incorporate the effect of currency exposure and different proxies of equity performance. We find that for many investors, access to funds of hedge funds is as valuable as access to international equity markets. Difference between investors in different countries are documented. These differences are due to the relative performance of the different equity markets as well as the fact that hedge fund exposure contains currency exposure that vigilant investors should take care in hedging to reduce unnecessary volatility.

  • 118.
    Hardie, Staffan
    Mälardalen University, Department of Mathematics and Physics.
    Drag Estimations on Experimental Aircraft Using CFD2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    The drag approximations done in the initial design phase needed to be verified. A model of the aircraft has been analyzed with CFD and results examined to see how accurate the estimations were. A step by step analysis was made and then a simulation was run. The drag results of the CFD analysis did not meet the goal of the initial design study. Several reasons for this are discussed. The analysis shows that the aircraft design works well aerodynamically but also shows a few areas where the design can be improved.

  • 119.
    Hoelgaard, Lena
    Mälardalen University, Department of Mathematics and Physics.
    Läsförståelse i problemlösning: Analys av Gudrun Malmers ALP 2 och ALP32007Independent thesis Basic level (professional degree)Student thesis
    Abstract [sv]

    Jag vill med mitt examensarbete mäta ALP-testets validitet. Syftet blir därför att analysera ALP-testet i sig och försöka finna om ALP verkligen mäter det som avses. Jag använder tre metoder: screening, innehållsanalys och observationer. Dessa metoder genererar ett stort antal data vilka jag sedan grundar mina resultat på. Utifrån mina resultat kan jag konstatera att validiteten i ALP 2 och ALP 3 är relativt låg. Jag anser att ALP-testet är ett material vilket jag inte kan ha en direkt praktisk nytta av i min undervisning. Däremot är materialet väl värt att revidera och på så sätt öka dess validitet.

  • 120.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    A Global Optimization Approach for Integrated Design and Parameter Estimation in Process Engineering2006Other (Other academic)
  • 121.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    An adaptive radial basis algorithm (ARBF) for expensive black-box global optimization2008In: Journal of Global Optimization, ISSN 1573-2916, Vol. 41, no 3, p. 447-464Article in journal (Refereed)
    Abstract [en]

    Powerful response surface methods based on kriging and radial basis function (RBF) interpolation have been developed for expensive, i.e. computationally costly, global nonconvex optimization. We have implemented some of these methods in the solvers rbfSolve and EGO in the TOMLAB Optimization Environment (http://www.tomopt.com/tomlab/). In this paper we study algorithms based on RBF interpolation. The practical performance of the RBF algorithm is sensitive to the initial experimental design, and to the static choice of target values. A new adaptive radial basis interpolation (ARBF) algorithm, suitable for parallel implementation, is presented. The algorithm is described in detail and its efficiency is analyzed on the standard test problem set of Dixon-Szego. Results show that it outperforms the published results of rbfSolve and several other solvers.

  • 122.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    An Adaptive Radial Basis Algorithm (ARBF) for Expensive Black-Box Mixed-Integer Constrained Global Optimization2005In: Conference on Least Squares and Optimization: In honour of professor Per-Åke Wedin, Umeå University, November 16-17, 2005, 2005Conference paper (Refereed)
  • 123.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    An Adaptive Radial Basis Algorithm (ARBF) for Mixed-Integer Expensive Constrained Global Optimization2005In: Proceedings of the International Workshop on Global Optimization: San Jose, Almeria, Spain, September 18-22, 2005, 2005, p. 133-140Conference paper (Refereed)
  • 124.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    Mixed-integer expensive global optimization with TOMLAB2004Conference paper (Other academic)
  • 125.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    Nonlinear Systems Modeling and Optimization: State-of-Art and Perspectives: Panel presentation2006In: EURO XXI, 21th European Conference on Operational Research, Reykavik, Iceland, July 2-5, 2006: OR for Better Management of Sustainable Development, 2006Conference paper (Refereed)
  • 126.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    Radial Basis Algorithms for Expensive Derivative-Free Black-Box Mixed-Integer Constrained Global Optimization2007In: Conference Proceeding GOR Workshop on Global Optimization: 79th Meeting of the GOR Working Group, Physikzentrum, Bad Honnef, 18-19 October 2007, 2007Conference paper (Refereed)
  • 127.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    TOMLAB - Unique Features for Advanced Optimization in MATLAB2006Other (Other academic)
  • 128.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    TOMLAB - Unique Features for Optimization in MATLAB2004Conference paper (Refereed)
  • 129.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Edvall, Marcus
    Göran, Anders
    Daily Milk Cow Feed Optimization in the Nordic Countries with TOMLAB2006In: EURO XXI, 21th European Conference on Operational Research, Reykavik, Iceland, July 2-5, 2006: OR for Better Management of Sustainable Development, 2006Conference paper (Refereed)
  • 130.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Edvall, Marcus
    Göran, Anders
    TOMLAB - Large-Scale Optimization in MATLAB, LABVIEW and .NET2007In: ICCOPT II & MOPTA-07, 2nd Mathematical Programming Society International Conference on Continuous Optimization: McMaster University, Hamilton, Canada, August 12-16, 2007, 2007Conference paper (Refereed)
  • 131.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Edvall, Marcus M.
    Mälardalen University, Department of Mathematics and Physics.
    The TOMLAB optimization environment2004Licentiate thesis, monograph (Other scientific)
  • 132.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Edvall, Marcus M.
    Mälardalen University, Department of Mathematics and Physics.
    THE TOMLAB OPTIMIZATION ENVIRONMENT2004In: Modeling Languages in Mathematical Optimization, Kluwer Academic Publishers, 2004, p. 369-376Chapter in book (Refereed)
  • 133.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Edvall, Marcus M.
    Göran, Anders
    Mixed-Integer expensive constrained global optimization with TOMLAB2005In: The eight SIAM conference about Optimization: Stockholm, May 15-19, 2005, 2005Conference paper (Refereed)
  • 134.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Edvall, Marcus M.
    Mälardalen University, Department of Mathematics and Physics.
    Göran, Anders
    Mälardalen University, Department of Mathematics and Physics.
    Tomlab - For Large-Scale Robust Optimization2003In: Proceedings for the Nordic Matlab Conference, 2003Conference paper (Other scientific)
  • 135.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Göran, Anders
    Mälardalen University, Department of Mathematics and Physics.
    User's Guide for Tomlab v3.2.12002Report (Other academic)
  • 136.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Kocjan, Waldemar
    Mälardalen University, Department of Mathematics and Physics.
    AUTOPACK - Algorithms for Automated Container Loading2008In: Journal of Numerical and Applied Mathematics, ISSN 0868-6912, Vol. 96, no 1, p. 105-118Article in journal (Refereed)
    Abstract [en]

    The container loading problem aims at optimal packing of boxes of different dimensions into available containers with respect to some objective function. This problem arises in areas like distribution and logistics. Since the scale of distribution and amount of distributed goods grows rapidly, so does the need for more energy effective and environmentally friendly distribution methods.This paper  considers a single container loading problem motivated by a real life application. The formulation includes an objective function for maximizing utilization of a container and additional constraints such as a predefined order and priorities between boxes. A short evaluation of the algorithm is presented as well as some directions for future development.

  • 137.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Kocjan, Waldemar
    Mälardalen University, School of Education, Culture and Communication.
    Generating Stable Loading Patterns for Pallet Loading Problems2008In: First Workshop on Bin Packing and Placement Constraints (BPPC’08), 2008, p. 1-6Conference paper (Refereed)
  • 138.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Lasdon, Leon
    Mälardalen University, Department of Mathematics and Physics.
    Pintér, János D.
    Mälardalen University, Department of Mathematics and Physics.
    Shoemaker, Christine
    Mälardalen University, Department of Mathematics and Physics.
    Ugray, Zsolt
    Mälardalen University, Department of Mathematics and Physics.
    Advanced global optimization – Scientific and engineering applications2004Conference paper (Other academic)
  • 139.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Quttineh, Nils-Hassan
    Mälardalen University, Department of Mathematics and Physics.
    Radial Basis Algorithms for Mixed-Integer Expensive Constrained Global Optimization2006In: Second International Workshop on SURROGATE MODELLING AND SPACE MAPPING FOR ENGINEERING OPTIMIZATION: SMSMEO-06, Copenhagen, Denmark, November 9-11, 2006, 2006Conference paper (Refereed)
  • 140.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Quttineh, Nils-Hassan
    Mälardalen University, School of Education, Culture and Communication.
    The influence of different Experimental Designs on the performance of Surrogate Model based Costly Global Optimization Solvers2008Conference paper (Refereed)
  • 141.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Quttineh, Nils-Hassan
    Mälardalen University, School of Education, Culture and Communication.
    The influence of Experimental Designs on the Performance of Surrogate Model Based Costly Global Optimization Solvers2009In: Studies in Informatics and Control, ISSN 1220-1766, E-ISSN 1841-429X, Vol. 18, no 1, p. 87-95Article in journal (Refereed)
    Abstract [en]

    When dealing with costly objective functions in optimization, one good alternative is to use a surrogate model approach. A common feature for all such methods is the need of an initial set of points, or "experimental design", in order to start the algorithm. Since the behavior of the algorithms often depends heavily on this set, the question is how to choose a good experimental design. We investigate this by solving a number of problems using different designs, and compare the outcome with respect to function evaluations and a root mean square error test of the true function versus the surrogate model produced. Each combination of problem and design is solved by 3 different solvers available in the TOMLAB optimization environment. Results indicate two designs as superior.

  • 142.
    Holmström, Kenneth
    et al.
    Mälardalen University. Mälardalen University, Department of Mathematics and Physics.
    Quttineh, Nils-Hassan
    Mälardalen University. Mälardalen University, School of Education, Culture and Communication.
    Edvall, Marcus
    Tomlab Optimization Inc..
    Adaptive Radial Basis Algorithms (ARBF) for Expensive Black-Box Global MINLP Optimization2008In: SIOPT08 - SIAM Optimization, Boston, USA, 2008Conference paper (Refereed)
    Abstract [en]

    Parallel implementations of the adaptive radial basis function algorithm (ARBF)for computationally costly optimization are presented.Modifications of  ARBF to improve robustness and speed are discussed.The algoritm is implemented in solver PARFMIP in the TOMLAB Optimization Environment (http://tomopt.com/). Solvers in TOMLAB are used to solve global and local subproblems.Results and comparisons with other solvers are presentedfor a large set of global optimization test problems.Performance on some costly real-life applications are reported.

  • 143.
    Holmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Quttineh, Nils-Hassan
    Mälardalen University, School of Education, Culture and Communication.
    Edvall, Marcus
    Tomlab Optimization Inc..
    An adaptive radial basis algorithm (ARBF) for expensive black-box mixed-integer constrained global optimization2008In: Optimization and Engineering, ISSN 1389-4420, E-ISSN 1573-2924, Vol. 9, no 4, p. 311-339Article in journal (Refereed)
    Abstract [en]

    Response surface methods based on kriging and radial basis function (RBF) interpolationhave been successfully applied to solve expensive, i.e. computationally costly,global black-box nonconvex optimization problems.In this paper we describe extensions of these methods to handle linear, nonlinear, and integer constraints. In particular, algorithms for standard RBF and the new adaptive RBF (ARBF) aredescribed. Note, however, while the objective function may be expensive, we assume that any nonlinear constraints are either inexpensive or are incorporated into the objective function via penalty terms. Test results are presented on standard test problems, both nonconvexproblems with linear and nonlinear constraints, and mixed-integernonlinear problems (MINLP). Solvers in the TOMLAB OptimizationEnvironment (http://tomopt.com/tomlab/) have been compared,specifically the three deterministic derivative-free solversrbfSolve, ARBFMIP and EGO with three derivative-based mixed-integernonlinear solvers, OQNLP, MINLPBB and MISQP, as well as the GENOsolver implementing a stochastic genetic algorithm. Results showthat the deterministic derivative-free methods compare well with thederivative-based ones, but the stochastic genetic algorithm solver isseveral orders of magnitude too slow for practical use.When the objective function for the test problems is costly to evaluate, the performance of the ARBF algorithm proves to be superior.

  • 144.
    Hoolmström, Kenneth
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Quttineh, Nils-Hassan
    Mälardalen University, Department of Mathematics and Physics.
    An Adaptive Radial Basis Algorithm (ARBF) for Expensive Black-Box Mixed-Integer Constrained Global Optimization2006In: EURO XXI, 21th European Conference on Operational Research, Reykavik, Iceland, July 2-5, 2006: OR for Better Management of Sustainable Development, 2006Conference paper (Refereed)
  • 145.
    Hunt, Daniel
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Olsson, Magnus
    Mälardalen University, Department of Mathematics and Physics.
    ATSVIS: Airport Traffic Surveillance and Visual Information System2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    The primary objective with the thesis is to formulate a concept on how to do the air traffic safer, both on the land and in the air. The concept got the name ATSVIS, which stands for Airport Traffic Surveillance and Visual Information System. ATSVIS is intended to give instructions what new ideas and new technology can do, to allocate the pilot and the traffic management. ATSVIS also intend to automate and to simplify the air traffic. The concept is formulated after own ideas and from interviews with people in the flight industry. The central work of the thesis is a simulator in which one can show and to examine how ATSVIS functions work.

  • 146.
    Häggstål, Daniel
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Kvarnström, Andreas
    Mälardalen University, Department of Mathematics and Physics.
    Dotzauer, Erik
    Mälardalen University, Department of Mathematics and Physics.
    Holmström, Kenneth
    Mälardalen University, Department of Mathematics and Physics.
    Fuel mix optimization of combined heat and power production utilizing a simulation model2004Conference paper (Refereed)
  • 147.
    Johansson, LarsErik
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Aldaeus, F
    Royal Institute of Technology, Sweden.
    Jonsson, G
    Mälardalen University, Department of Mathematics and Physics.
    Hamp, S
    Mälardalen University, Department of Biology and Chemical Engineering.
    Roeraade, J
    Royal Institute of Technology, Sweden.
    Determination of conductivity of bacteria by using cross-flow filtration2006In: Biotechnology letters, ISSN 0141-5492, E-ISSN 1573-6776, Vol. 28, no 8, p. 601-603Article in journal (Refereed)
    Abstract [en]

    An important property of the bacterial surface is its conductivity. To obtain reliable conductivity values, it is essential to handle the cells as gently as possible during the measurement procedure. We have developed a method where a standard conductivity meter is used in combination with cross-flow filtration, thus avoiding repeated centrifugation and resuspension. With this method, the conductivity of Bacillus subtilis was determined to be 7000 mu S/cm, which is a deviation from previously published data by almost an order of a magnitude.

  • 148.
    Johansson, Sabina
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Hertze, Malin
    Mälardalen University, School of Education, Culture and Communication.
    Hur får man fram matematiken i ett laborativt material?2008Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med vårt examensarbete är att studera hur lärare ser på möjligheter att lyfta fram matematiken i undervisningen med laborativt material. Vi har valt att göra en kvalitativ undersökning med intervjuer av lärare. Resultatet av intervjuerna visar att de flesta lärare ansåg att eleverna ska komma på matematiken själva. De menade att lärarna ska vara tydliga med syftet och ha en genomtänkt tanke vid användning av spel och laborationer. De ansåg också att det var viktigt att vara positiv och entusiastisk gentemot spel och laborationer. De flesta lärarna tyckte att matematiken kommer automatiskt om eleverna är mogna för det som ska läras in. Lärarna hade olika uppfattningar om vilka förkunskaper de ansåg en lärare bör ha när de använder sig av laborativt material. De flesta ansåg att ett stort intresse och förståelse för matematik kan räcka. I diskussion kommer vi att diskutera det som fann intressant i slutsatsen och diskutera inledningen.

  • 149.
    Johnsson, Lena
    Mälardalen University, Department of Mathematics and Physics.
    Matematikläxa?: Vilka uppfattningar har pedagoger om matematikläxor?2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Syftet med den här uppsatsen är att undersöka vilka fördelar och nackdelar det finns med matematikläxor. För att kunna svara på det har jag valt att göra en kvalitativ enkätundersökning. De svarande är sex stycken undervisande matematiklärare med elever i år 1-5 och två stycken matematiklärarutbildare. Resultatet från enkätundersökningen visade att fördelarna med matematikläxor enligt pedagogerna är att eleverna får befästa och färdighetsträna sina kunskaper. De positiva effekterna som kan uppnås med hjälp av matematikläxor är snabbare inlärning och att föräldrarna blir involverade i sitt barns matematikutveckling. De nackdelar som finns med matematikläxorna enligt pedagogerna är att alla elever inte har samma tillgång till hjälp hemma vilket leder till att det blir svårt att göra läxan om de fastnar på något moment. Negativa effekter som matematikläxorna kan leda till är stress och att eleven tappar intresset för ämnet.

  • 150.
    Jonsson, Gunnar
    et al.
    Mälardalen University, Department of Mathematics and Physics.
    Gustafsson, Peter
    Mälardalen University, Department of Mathematics and Physics.
    Enghag, Margareta
    Mälardalen University, Department of Mathematics and Physics.
    Context rich problems - an educational tool in physics teaching2005In: ESERA 2005 - CRESILS, Barcelona, Spain, 2005Conference paper (Refereed)
123456 101 - 150 of 284
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