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  • 1.
    Akram, Usman
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Metson, Genevieve
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering. Linköping University, Centre for Climate Science and Policy Research, CSPR.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Wennergren, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Closing Pakistan’s yield gaps through nutrient recycling2018In: Frontiers in Sustainable Food Systems, E-ISSN 2571-581X, p. 1-14, article id 00024Article in journal (Refereed)
    Abstract [en]

    Achieving food security will require closing yield gaps in many regions, including Pakistan. Although fertilizer subsidies have facilitated increased nitrogen (N) application rates, many staple crop yields have yet to reach their maximum potential. Considering that current animal manure and human excreta (bio-supply) recycling rates are low, there is substantial potential to increase the reuse of nutrients in bio-supply. We quantified 2010 crop N, phosphorus (P), and potassium (K) needs along with bio-supply nutrient availability for Pakistani districts, and compared these values to synthetic fertilizer use and costs. We found that synthetic fertilizer use combined with low bio-supply recycling resulted in a substantial gap between nutrient supply and P and K crop needs, which would cost 3 billion USD to fill with synthetic fertilizers. If all bio-supply was recycled, it could eliminate K synthetic fertilizer needs and decrease N synthetic fertilizer needs to 43% of what was purchased in 2010. Under a full recycling scenario, farmers would still require an additional 0.28 million tons of synthetic P fertilizers, costing 2.77 billion USD. However, it may not be prohibitively expensive to correct P deficiencies. Pakistan already spends this amount of money on fertilizers. If funds used for synthetic N were reallocated to synthetic P purchases in a full bio-supply recycling scenario, crop needs could be met. Most recycling could happen within districts, with only 6% of bio-supply requiring between-district transport when optimized to meet national N crop needs. Increased recycling in Pakistan could be a viable way to decrease yield gaps.

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    Closing Pakistan’s Yield Gaps Through Nutrient Recycling
  • 2.
    Akram, Usman
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Wennergren, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Tonderski, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Metson, Genevieve
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Enhancing nutrient recycling from excreta to meet crop nutrient needs in Sweden - a spatial analysis2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 10264Article in journal (Refereed)
    Abstract [en]

    Increased recycling of nutrient-rich organic waste to meet crop nutrient needs is an essential component of a more sustainable food system. However, agricultural specialization continues to pose a significant challenge to balancing crop nutrient needs and the nutrient supply from animal manure and human excreta locally. For Sweden, this study found that recycling all excreta (in 2007) could meet up to 75% of crop nitrogen and 81% of phosphorus needs, but that this would exceed crop potassium needs by 51%. Recycling excreta within municipalities could meet 63% of crop P nutrient needs, but large regional differences and imbalances need to be corrected to avoid over or under fertilizing. Over 50% of the total nitrogen and phosphorus in excreta is contained in just 40% of municipalities, and those have a surplus of excreta nutrients compared to crop needs. Reallocation of surpluses (nationally optimized for phosphorus) towards deficit municipalities, would cost 192 million USD (for 24 079 km of truck travel). This is 3.7 times more than the total NPK fertilizer value being transported. These results indicate that Sweden could reduce its dependence on synthetic fertilizers through investments in excreta recycling, but this would likely require valuing also other recycling benefits.

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  • 3.
    Akram, Usman
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization .
    Wennergren, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology.
    Tonderski, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Biology.
    Metson, Geneviéve S.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology.
    Optimizing Nutrient Recycling From Excreta in Sweden and Pakistan: Higher Spatial Resolution Makes Transportation More Attractive2019In: Frontiers in Sustainable Food Systems, ISSN 2571-581X, Vol. 3Article in journal (Refereed)
    Abstract [en]

    Recycling essential plant nutrients like nitrogen (N), phosphorus (P), and potassium (K) from organic waste such as human and animal excreta will be an essential part of sustainable food systems and a circular economy. However, transportation is often cited as a major barrier to increased recycling as organic waste is heavy and bulky, and distances between areas of abundant waste may be far from areas with a need for fertilizers. We investigated the effect of increased input data spatial resolution to an optimization model on the weight, distance, and spatial patterns of transport. The model was run in Sweden and in Pakistan to examine cost-effectiveness of transporting excess excreta to areas of crop need after local recycling. Increasing the resolution of input data from political boundaries (municipalities and districts) to 0.083 decimal grids increased the amount of N requiring transport by 12% in Pakistan and increased P requiring transport by 14% in Sweden. The average distance decreased by 67% (to 44 km) in Pakistan but increased by 1 km in Sweden. Further increasing the resolution to 5 km grids in Sweden decreased the average transportation distance by 9 km (down to 123 km). In both countries, increasing resolution also decreased the number of long-distance heavy transports, and as such costs did not increase as much as total distance and weight transported. Ultimately, transportation in Pakistan seemed financially beneficial: the cost of transport only represented 13% of the NPK fertilizer value transported, and total recycling could even cover 78% of additional fertilizer purchases required. In Sweden, the cost of transporting excreta did not seem cost effective without valuing other potential benefits of increased recycling: costs were three times higher than the fertilizer value transported in excreta at the 5 km resolution. In summary, increasing input data resolution created a more realistic picture of recycling needs. This also highlighted more favorable cost to fertilizer value ratios which could make it easier to move forward with industry and government partners to facilitate productive recycling. Our analysis shows that in both countries increased recycling can result in better spatial nutrient balances.

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  • 4.
    Berglund, Per
    et al.
    KTH Royal Institute of Technology, Sweden.
    Dannetun, Per
    Linköping University, University Services.
    Lee Chan, Wai
    Nanyang Technological University, Singapore.
    Gold, Julie
    Chalmers University of Technology, Sweden.
    Han, Sam
    Nanyang Technological University, Singapore.
    Hansson, Heidi
    Umeå University, Sweden.
    Harvey, Simon
    Chalmers University of Technology, Sweden.
    Song Huang, Jun
    National Institute of Education, Singapore.
    Larsson, Ann-Charlotte
    Linnaeus University, Sweden.
    Linton, Steven
    Örebro University, Sweden.
    McInerney, Gerald
    Karolinska Institutet, Sweden.
    Magnell, Marie
    KTH Royal Institute of Technology, Sweden.
    Popov, Oleg
    Umeå University, Sweden.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Richards, Tobias
    University of Borås, Sweden.
    Song, Juha
    Nanyang Technological University, Singapore.
    Switzer, Adam D.
    Nanyang Technological University, Singapore.
    Tegler Jerselius, Kristina
    Swedish Higher Education Authority, Sweden.
    Vikström, Susanne
    Umeå University, Sweden.
    Wikström, Martin
    Royal Swedish Academy of Engineering Sciences, Sweden.
    Trevor Yu, Kang Yang
    Nanyang Technological University, Singapore.
    Yeo, Jesvin Puay-Hwa
    Nanyang Technological University, Singapore.
    Zary, Nabil
    Nanyang Technological University, Singapore.
    Pohl, Hans
    The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), Sweden.
    Ellervik, Ulf
    Lund University, Sweden.
    Linking Education and Research: A Roadmap for Higher Education Institutions at the Dawn of the Knowledge Society2019Other (Other academic)
    Abstract [en]

    In an era characterized by a move towards a “knowledge society”, universities are central in fostering “knowledgeability”, that is the reflexive understanding of knowledge in knowledge societies. The objective of “knowledgeability” can be met through creating a stronger link between education and research. Furthermore, overall student performance, for example in critical thinking and problem solving, can be improved if research-related activities are incorporated into the curriculum. The aim of this paper is to use international examples to discuss the research- education nexus from four different perspectives, namely context, policy, implementation and quality, with case studies from higher education institutions in Singapore and Sweden. We suggest that different integrative technologies can be used to enhance the links, but it will be essential to consider the inputs of training, service and support in using new technology. Interestingly, the act of evaluating the link between education and research will increase awareness of this linkage by stakeholders involved in both education and research. In turn the link can be strengthened, contributing to increased quality in both education and research.

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    Linking Education and Research: A Roadmap for Higher Education Institutions at the Dawn of the Knowledge Society
  • 5.
    Ekström, Joakim
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Kristoffersson, Ida
    Trafikanalys, Sweco TransportSystem AB, Stockholm.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Surrogatbaserad optimering av avgiftsnivåer i trängselavgiftssystem2015Report (Other academic)
    Abstract [sv]

    Trängselskatt finns idag i både Stockholm och Göteborg, och det är troligt att utformningen av dessa trängselskattesystem kommer att justeras framöver med avseende på avgiftsnivå, placering och tidpunkt. För Stockholm finns beslut om ändring från januari 2016 och i Göteborg ändrades avgiftsnivåerna i januari 2015. I detta projekt utvecklas metoder som ska kunna ge stöd vid justering av avigiftsnivåer, så att en så stor samhällsekonomisk nytta som är möjligt uppnås med trängselskattesystemet.

    För storstadsområden, där det under rusningstrafik är trängsel i delar av nätverket, är trängselskatt främst intressant att analysera med dynamiska transportmodeller. Tidigare utveckling av metoder för optimal avgiftssättning har dock främst fokuserat på statiska modeller, exempelvis Emme, som har kända problem med att korrekt uppskatta förändring i restider när det är trängsel i delar av trafiknätverket. I detta projekt har vi därför tillämpat surrogat-baserad optimering, som är en metodansats som ställer få krav på vilken transportmodell som används. Den dynamiska transportmodellen Regent/VisumDUE finns sedan tidigare implementerad för Stockholmsregionen, och har därför även använts i detta projekt. VisumDUE är en makroskopisk nätutläggningsmodell med dynamiskt ruttval, och Regent är en efterfrågemodell som innehåller resgenerering, färdmedelsval och destinationsval för arbetsresor[1].

    Surrogat-baserad optimering erbjuder ett ramverk för optimering av problem med beräkningsmässigt kostsamma målfunktioner. Genom att approximera en funktionsyta till samplade punkter från den kostsamma målfunktionen, kan optimeringen istället göras över den approximerade funktionsytan. För Regent/VisumDUE tar utvärderingen av ett givet trängselskattescenario ca tio timmar, och det är denna beräkningstid som gör målfunktionen kostsam. Givet ett antal samplade punkter, görs ytterligare sampling utifrån en given strategi för att förbättra approximationen, så kallad iterativ sampling. Inom ramverket finns dock en mängd möjligheter för hur de olika komponenterna designas. Därför är det svårt att utvärdera surrogat-baserad optimering med endast Regent/VisumDUE. En statisk transportmodell har därför använts för att utvärdera ett antal kombinationer av samplingsstrategi och funktionsyta. Den mest lovande kombinationen har sedan även utvärderats med Regent/VisumDUE. För att vara praktiskt tillämpbart i framtiden har fokus i projektet varit att utvärdera hur metodansatsen fungerar när antalet möjliga tulluppsättningar är kraftigt begränsat (20-40 stycken).

    Det scenario som har använts som grund i projektet är trängselskatt i Stockholm på nuvarande tullring, på Essingeleden samt på innerstadsbroarna. Skatten är differentierad med avseende på riktning, vilket ger sex olika skattenivåer att optimera. Optimeringen har gjorts för trängselskattenivå under maxtimmen. I det dynamiska fallet har trängselskattens nivå utanför maxtimme funnits med som indata, men samma tidsprofil som på nuvarande tullring har antagits i alla scenarier (avgiftstrappa 50%, 75%, 100%, 75%, 50%). Utvärderingen med den statiska transportmodellen visar att lösningar nära globalt optimum kan uppnås med endast 40 utvärderade trängselskattenivåer, och en tydlig förbättring av den samhällsekonomiska nyttan uppnås redan vid 20 utvärderade trängselskattenivåer.

    Även med ett kraftigt begränsat antal utvärderingar av den kostsamma målfunktionen i Regent/VisumDUE, har vi visat att det är möjligt att använda metodansatsen. En tydlig förbättring av den samhällsekonomiska nyttan uppnås med endast 22 utvärderade trängselskattenivåer. Ytterligare experiment skulle dock behövas för att undersöka hur stor denna förbättring är i förhållande till vad som skulle kunna uppnås.

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  • 6.
    Ekström, Joakim
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Kristoffersson, Ida
    Centre for Transport Studies, KTH Royal Institute of Technology, Stockholm, Sweden.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Surrogate-based optimization of cordon toll levels in congested traffic networks2016In: Journal of Advanced Transportation, ISSN 0197-6729, E-ISSN 2042-3195, Vol. 50, no 6, p. 1008-1033Article in journal (Refereed)
    Abstract [en]

    The benefits, in terms of social surplus, from introducing congestion pricing schemes in urban networks are depending on the design of the pricing scheme. The major part of the literature on optimal design of congestion pricing schemes is based on static traffic assignment, which is known for its deficiency in correctly predict travels in networks with severe congestion. Dynamic traffic assignment can better predict travel times in a road network, but are more computational expensive. Thus, previously developed methods for the static case cannot be applied straightforward. Surrogate-based optimization is commonly used for optimization problems with expensive-to-evaluate objective functions. In this paper we evaluate the performance of a surrogate-based optimization method, when the number of pricing schemes which we can afford to evaluate (due to the computational time) is limited to between 20 and 40. A static traffic assignment model of Stockholm is used for evaluating a large number of different configurations of the surrogatebased optimization method. Final evaluation is done with the dynamic traffic assignment tool VisumDUE, coupled with the demand model Regent, for a Stockholm network including 1 240 demand zones and 17 000 links. Our results show that the surrogate-based optimization method can indeed be used for designing a congestion pricing scheme which return a high social surplus.

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  • 7.
    Ekström, Joakim
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Surrogate-based optimisation of toll levels in congestion pricing schemes2014In: Transportation Infrastructure: Proceedings of the 19th International Conference of Hong Kong Society for Transportation Studies (HKSTS) / [ed] Z. Leng and Y. H. Wang, Hong Kong: Hong Kong Society of Transportation Studies Limited , 2014, p. 209-216Conference paper (Refereed)
    Abstract [en]

    There has recently been a growing interest in analysing road pricing schemes in urban areas using dynamic traffic assignment (DTA) tools. Finding optimal toll levels in cordon based road pricing schemes has so far mainly been studied using either derivative-free heuristics or ascent methods. For future use of DTA tools such methods are not suitable and in this paper we investigate how a surrogate modelling framework can be used instead. We focus on cases when the number of costly objective function evaluations is limited to between 20 and 40. In order to allow a large number of different configurations of the surrogate modelling framework to be evaluated, a static user equilibrium model is used for simulating the road users’ response to a given pricing scheme. The results show that for a realistic scenario, valuable information on close to optimal toll levels can be achieved with only 20 costly function evaluations.

  • 8.
    Ekström, Joakim
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Kristoffersson, Ida
    Sweco TransportSystem.
    Simulation based optimisation of toll levels in urban road traffic networks2014Conference paper (Other academic)
    Abstract [en]

    There has recently been a growing interest in analysing road pricing schemes in urban areas using dynamic traffic assignment (DTA) tools. The motivation behind this development is the problem for static transportation models to accurately predict travel time savings, from introducing road pricing, in networks with severe congestion. Finding optimal toll levels and locations in urban road traffic networks has so far mainly been studied using either derivative-free heuristics (e.g. genetic algorithms and simulated annealing) or ascent methods. Both approaches rely on fast computations of the road users response (traffic flows, travel times and demands), given the road pricing scheme, and for the case of ascent methods, the methods also rely on fast computations (or rather approximation) of derivatives. Using DTA tools for evaluating the road users’ response to a pricing scheme is, however, very computationally expensive. Previously developed methods are therefore not suitable to use together with DTA.

    Surrogate models, e.g. in terms of response surfaces, are commonly used for optimisation problems with expensive-to-evaluate objective functions. The surrogate model is used for approximating the expensive-to-evaluate objective function, and the optimisation is then done on the surrogate model instead. The performances of optimisation methods based on surrogate models are, however, dependent on experimental design, infill strategy and choice of surrogate model itself. The experimental design will give the initial set of toll levels, for which the DTA needs to be evaluated, the infill strategy determined additional toll levels to be evaluated by the DTA, and the choice of surrogate model will give the functional form to be fitted to the sampled toll levels.

    We apply a surrogate model framework for optimising toll levels in a multiple cordon pricing scheme. In the first stage we evaluate the experimental design, infill strategy and choice of surrogate model, using a static macroscopic traffic model.  This allows a large number of experiments to be carried out, which would not be possible with a DTA tool. It also allows us to compare the performance of the surrogate modelling approach with other global optimisation methods. In the second stage, the insight which has been gained from the experiments with the static model is used when applying the surrogate modelling approach to a DTA model of Stockholm.

    Computational results are presented for a Stockholm network with three cordons, each with differentiated toll level in both directions, resulting in a total of six toll level variables. Surrogate models in the form of Radial Basis Functions and Kriging models are evaluated with a static model of Stockholm, for different initial experimental designs, infill strategies and choice of surrogate models. In comparison with previously developed derivative based methods for static models, our results show that the surrogate based optimisation approach performs better, since it allows for metaheuristic methods to search for global optimal solutions efficiently.

  • 9.
    Holmström, Kenneth
    et al.
    Department of Mathematics and Physics, Mälardalen University, Västerås, Sweden.
    Quttineh, Nils-Hassan
    Department of Mathematics and Physics, Mälardalen University, Västerås, Sweden.
    Edvall, Marcus M.
    Tomlab Optimization Inc., Pullman, WA, USA.
    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 3, 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 handlelinear, 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 assumethat any nonlinear constraints are either inexpensive or are incorporatedinto 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.

  • 10.
    Häll, Carl Henrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ceder, Avishai (Avi)
    Department of Civil and Environmental Engineering, University of Auckland, New Zealand, and International Development and Cooperation (IDEC), Hiroshima University, Hiroshima, Japan.
    Ekström, Joakim
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Adjustments of public transit operations planning process for the use of electric buses2019In: Journal of Intelligent Transportation Systems / Taylor & Francis, ISSN 1547-2450, E-ISSN 1547-2442, Vol. 23, no 3, p. 216-230Article in journal (Refereed)
    Abstract [en]

    This work investigates and discusses how the introduction of electric buses (EB), both battery and plug-in hybrid EB, will and should change the operations planning of a public transit system. It is shown that some changes are required in the design of a transit route network, and in the timetabling and vehicle scheduling processes. Other changes are not required, but are advisable, using this opportunity upon the introduction of EB. The work covers the main characteristics of different types of EB with a short description, including the most popular charging technologies, and it presents the generally accepted transit operations planning process. Likewise, it describes and analytically formulates new challenges that arise when introducing EB. The outcome of the analyses shows that multiple new considerations must take place. It is also shown that the different charging techniques will influence the operations planning process in different ways and to a varying extent. With overnight, quick and continuous charging, the main challenges are in the network route design step, given the possibility of altering the existing network of routes, with efficient and optimal changes of the timetabling and vehicle scheduling components. An illustrative example, based on four bus lines in Norrköping, Sweden, is formulized and introduced using three problem instances of 48, 82, and 116 bus trips. The main results exhibit the minimum number of vehicles required using different scenarios of charging stations.

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  • 11.
    Häll, Carl Henrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ceder, Avishai (Avi)
    Transportation Research Center, Department of Civil and Environmental Engineering, The University of Auckland, New Zealand; Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
    Ekström, Joakim
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Adjustments of Public Transit Operations Planning Process for the Use of Electric Buses2017In: TRB Annual Meeting Online, 2017, Transportation Research Board , 2017Conference paper (Refereed)
    Abstract [en]

    This work investigates and discusses how the introduction of electric buses (EB), both battery and plug-in hybrid EB, will and should change the operations planning of a public transit system. It is shown that some changes are required in the design of a transit route network, and in the timetabling and vehicle scheduling processes. Other changes are not required, but are advisable, using this opportunity upon the introduction of EB. The work covers the main characteristics of different types of EB with a short description, including the most popular charging technologies, and it presents the generally accepted transit operations planning process. Likewise, it describes and analytically formulates new challenges that arise when introducing EB. The outcome of the analyses shows that multiple new considerations must take place. It is also shown that the different charging techniques will influence the operations planning process in different ways and to a varying extent. With overnight, quick and continuous charging, the main challenges are in the network route design step, given the possibility of altering the existing network of routes, with efficient and optimal changes of the timetabling and vehicle scheduling components.

  • 12.
    Lindholm, Anna
    et al.
    Lund University, Sweden.
    Giselsson, Pontus
    Lund University, Sweden.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Johnsson, Charlotta
    Lund University, Sweden.
    Forsman, Krister
    Perstorp AB, Sweden.
    Production Scheduling in the Process Industry2013In: Proceedings for 22nd International Conference on Production Research, 2013, 2013Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to formulate an optimization model for the production scheduling problem at continuous production sites. The production scheduling activity should produce a monthly schedule that accounts for orders and forecasts of all products. The plan should be updated every day, with feedback on the actual production the previous day. The actual daily production may be lower than the planned production due to disturbances, e.g. disruptions in the supply of a utility. The work is performed in collaboration with Perstorp, a world-leading company within several sectors of the specialty chemicals market. Together with Perstorp, a list of specifications for the production scheduling has been formulated. These are formulated mathematically in a mixed-integer linear program that is solved in receding horizon fashion. The formulation of the model aims to be general, such that it may be used for any process industrial site.

  • 13.
    Lindholm, Anna
    et al.
    Lund University, Sweden.
    Johnsson, Charlotta
    Lund University, Sweden.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Henningsson, Mathias
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Wikner, Joakim
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Tang, Ou
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Nytzén, Nils-Petter
    Perstorp AB, Sweden.
    Forsman, Krister
    Perstorp AB, Sweden.
    Hierarchical Scheduling and Utility Disturbance Management in the Process Industry2013In: Proceedings for IFAC Conference on Manufacturing Modelling, Management and Control (MIM2013), 2013, Elsevier, 2013, p. 140-145Conference paper (Refereed)
    Abstract [en]

    The integration of scheduling and control in the process industry is a topic that has been frequently discussed during the recent years, but many challenges remain in order to achieve integrated solutions that can be implemented for large-scale industrial sites. In this paper we consider production control under disturbances in the supply of utilities at integrated sites together with the integration towards production scheduling. Utilities, such as steam and cooling water, are often shared between the production areas of a site, which enables formulation of an optimization problem for determining the optimal supply of utilities to each area at the occurrence of a disturbance. Optimization in two timescales is suggested to handle the scheduling and disturbance management problems in a hierarchical fashion. The suggested structure has been discussed with companies within the chemical process industry. A simple example is provided to show how the structure may be used

  • 14.
    Lindholm, Anna
    et al.
    Lund University, Sweden.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Hierarchical Production Scheduling: A Case Study at Perstorp2014In: 24th European Symposium on Computer Aided Process Engineering / [ed] Jiří Jaromír Klemeš, Petar Sabev Varbanov and Peng Yen Liew, Elsevier, 2014, p. 511-516Conference paper (Refereed)
    Abstract [en]

    Planning and scheduling are functions that have large economic impact in the chemical process industry. For integrated sites with many interconnected production areas, obtaining production schedules that respect all production-related constraints is a complex task. One important issue is the constraints due to disturbances in utilities, such as steam and cooling water. These are often site-wide disturbances that may make it impossible to maintain desired production rates in several production areas at a site. In this study, scheduling at two levels of the functional hierarchy at a site of a world lead chemical industry, Perstorp, is handled. The activities are denoted production scheduling (PS) and detailed production scheduling (DPS). Real data of incoming orders and utility disturbances are used to produce a production schedule and detailed production schedule for one month. The PS and DPS problems are formulated as optimization problems, where production-related constraints such as production rate constraints, inventory limitations, and start-up costs are included. The objective functions of the PS and DPS problems are formulated to reflect the importance of different issues at the site. The procedure aims to show how the hierarchical optimization framework may be used to provide decision support for how to operate the production at a site in order to maximize profit while minimizing the effects of site-wide disturbances.

  • 15.
    Olsson, Jonas
    et al.
    Linköping University, Department of Mathematics. Linköping University, Faculty of Science & Engineering.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Automating the planning of container loading for Atlas Copco: Coping with real-life stacking and stability constraints2019In: European Journal of Operational Research, ISSN 0377-2217, E-ISSN 1872-6860, Vol. 280, no 3, p. 1018-1034Article in journal (Refereed)
    Abstract [en]

    The Atlas Copco* distribution center in Allen, TX, supplies spare parts and consumables to mining and construction companies across the world. For some customers, packages are shipped in sea containers. Planning how to load the containers is difficult due to several factors: heterogeneity of the packages with respect to size, weight, stackability, positioning and orientation; the set of packages differs vastly between shipments; it is crucial to avoid cargo damage. Load plan quality is ultimately judged by shipping operators. This container loading problem is thus rich with respect to practical considerations. These are posed by the operators and include cargo and container stability as well as stacking and positioning constraints. To avoid cargo damage, the stacking restrictions are modeled in detail. For solving the problem, we developed a two-level metaheuristic approach and implemented it in a decision support system. The upper level is a genetic algorithm which tunes the objective function for a lower level greedy-type constructive placement heuristic, to optimize the quality of the load plan obtained. The decision support system shows load plans on the forklift laptops and has been used for over two years. Management has recognized benefits including reduction of labour usage, lead time, and cargo damage risk. (C) 2019 Elsevier B.V. All rights reserved.

    The full text will be freely available from 2021-07-27 08:31
  • 16.
    Quttineh, Nils-Hassan
    School of Education, Culture and Communication, Mälardalen University, Västeråas, Sweden.
    Algorithms for Costly Global Optimization2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    There exists many applications with so-called costly problems, which means that the objective function you want to maximize or minimize cannot be described using standard functions and expressions. Instead one considers these objective functions as \black box" where the parameter values are sent in and a function value is returned. This implies in particular that no derivative information is available.

    The reason for describing these problems as expensive is that it may take a long time to calculate a single function value. The black box could, for example, solve a large system of dierential equations or carrying out a heavy simulation, which can take anywhere from several minutes to several hours!

    These very special conditions therefore requires customized algorithms. Common optimization algorithms are based on calculating function values every now and then, which usually can be done instantly. But with an expensive problem, it may take several hours to compute a single function value. Our main objective is therefore to create algorithms that exploit all available information to the limit before a new function value is calculated. Or in other words, we want to nd the optimal solution using as few function evaluations as possible.

    A good example of real life applications comes from the automotive industry, where the development of new engines utilize advanced models that are governed by a dozen key parameters. The goal is to optimize the model by changing the parameters in such a way that the engine becomes as energy ecient as possible, but still meets all sorts of demands on strength and external constraints.

  • 17.
    Quttineh, Nils-Hassan
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Models and Methods for Costly Global Optimization and Military Decision Support Systems2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis consists of five papers. The first three deal with topics within costly global optimization and the last two concern military decision support systems.

    The first part of the thesis addresses so-called costly problems where the objective function is seen as a “black box” to which the input parameter values are sent and a function value is returned. This means in particular that no information about derivatives is available. The black box could, for example, solve a large system of differential equations or carry out   timeconsuming simulation, where a single function evaluation can take several hours! This is the reason for describing such problems as costly and why they require customized algorithms. The goal is to construct algorithms that find a (near)-optimal solution using as few function evaluations as possible. A good example of a real life application comes from the automotive industry, where the development of new engines utilizes advanced mathematical models that are governed by a dozen key parameters. The objective is to optimize the engine by changing these parameters in such a way that it becomes as energy efficient as possible, but still meets all sorts of demands on strength and external constraints. The first three papers describe algorithms and implementation details for these costly global optimization problems.

    The second part deals with military mission planning, that is, problems that concern logistics, allocation and deployment of military resources. Given a fleet of resource, the decision problem is to allocate the resources against the enemy so that the overall mission success is optimized. We focus on the problem of the attacker and consider two separate problem classes. In the fourth paper we introduce an effect oriented planning approach to an advanced weapon-target allocation problem, where the objective is to maximize the expected outcome of a coordinated attack. We present a mathematical model together with efficient solution techniques. Finally, in the fifth paper, we introduce a military aircraft mission planning problem, where an aircraft fleet should attack a given set of targets. Aircraft routing is an essential part of the problem, and the objective is to maximize the expected mission success while minimizing the overall mission time. The problem is stated as a generalized vehicle routing model with synchronization and precedence side constraints.

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    Models and Methods for Costly Global Optimization and Military Decision Support Systems
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    omslag
  • 18.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Holmström, Kenneth
    Division of Applied mathematics, Mälardalen University, SE-721 23 Västerås, Sweden.
    Implementation of a One-Stage Efficient Global Optimization (EGO) Algorithm2009Report (Other academic)
    Abstract [en]

    Almost every Costly Global Optimization (CGO) solver utilizes a surrogate model, or response surface, to approximate the true (costly) function. The EGO algorithm introduced by Jones et al. utilizes the DACE framework to build an approximating surrogate model. By optimizing a less costly utility function, the algorithm determines a new point where the original objective function is evaluated. This is repeated until some convergence criteria is fulfilled.The original EGO algorithm finds the new point to sample in a two-stage process. In its first stage, the estimates of the interpolation parameters are optimized with respect to already sampled points. In the second stage, these estimated values are considered true in order to optimize the location of the new point. The use of estimate values as correct introduces a source of error.Instead, in the one-stage EGO algorithm, both the parameters and the location of a new point are optimized at the same time, removing the source of error. This new subproblem becomes more difficult, but eliminates the need of solving two subproblems.Difficulties in implementing a fast and robust One-Stage EGO algorithm in TOMLAB are discussed, especially the solution of the new subproblem.

  • 19.
    Quttineh, Nils-Hassan
    et al.
    Mälardalen University, Västerås.
    Holmström, Kenneth
    Mälardalen University,Västerås.
    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.

  • 20.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Häll, Carl Henrik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ekström, Joakim
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ceder, Avi
    Department of Civil and Environmental Engineering, University of Auckland, New Zealand.
    Combined Timetabling and Vehicle Scheduling for Electric Buses2017In: Proceedings of the 22nd International Conference of Hong Kong Society for Transportation Studies (HKSTS), December 9-11, 2017, Hong Kong, China, Hong Kong: HKSTS , 2017, , p. 8Conference paper (Other academic)
    Abstract [en]

    In this paper we present a novel mathematical model, integrating the timetabling and vehicle schedulingproblems for electric buses. The objective is to minimize the number of buses while satisfying constraintsconcerning routing and charging, including design choices of where to install charging equipment. Weillustrate the different effects of tackling the timetabling and vehicle scheduling of electric buses as separateproblems or as a joint problem, both for fixed and variable headways. To do so, tests are performed with: (i) given timetable, i.e. solving only the vehicle scheduling problem, (ii) fixed headways for each line, (iii) variable headways. For these tests, a small case based on four bidirectional bus lines is used.

  • 21.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Military Aircraft Mission Planning: Efficient model-based metaheuristics approaches2015In: Optimization Letters, ISSN 1862-4472, E-ISSN 1862-4480, Vol. 9, no 8, p. 1625-1639Article in journal (Refereed)
    Abstract [en]

    We consider a military mission planning problem where a given fleet of aircraft should attack a number of ground targets. At each attack, two aircraft need to be synchronized in both space and time. Further, there are multiple attack options against each targets, with different target effects. The objective is to maximize the outcome of the entire attack, while also minimizing the mission timespan. Real-life mission planning instances involve only a few targets and a few aircraft, but are still computationally challenging. We present metaheuristic solution methods for this problem, based on an earlier presented model. The problem includes three types of decisions: attack directions, task assignments and scheduling, and the solution methods exploit this structure in a two-stage approach. In an outer stage, a heuristic search is performed with respect to attack directions, while in an inner stage the other two decisions are optimized, given the outer stage decisions. The proposed metaheuristics are capable of producing high-quality solutions and are fast enough to be incorporated in a decision support tool.

    Download full text (pdf)
    fulltext
  • 22.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lundberg, Kristian
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Holmberg, Kaj
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Effect Oriented Planning of Joint Attacks2013In: Optimization Theory, Decision Making, and Operations Research Applications / [ed] Athanasios Migdalas, Angelo Sifaleras, Christos K. Georgiadis, Jason Papathanasiou, Emmanuil Stiakakis, Springer-Verlag New York, 2013, p. 49-70Conference paper (Refereed)
    Abstract [en]

    We consider tactical planning of a military operation on a large target scene where a number of specific targets of interest are positioned, using a given number of resources which can be, for example, fighter aircraft, unmanned aerial vehicles, or missiles. The targets could be radar stations or other surveillance equipment, with or without defensive capabilities, which the attacker wishes to destroy. Further, some of the targets are defended, by, for example, Surface-to-Air Missile units, and this defense capability can be used to protect also other targets. The attacker has knowledge about the positions of all the targets and also a reward associated with each target. We consider the problem of the attacker, who has the objective to maximize the expected outcome of a joint attack against the enemy. The decisions that can be taken by the attacker concern the allocation of the resources to the targets and what tactics to use against each target. We present a mathematical model for the attacker’s problem. The model is similar to a generalized assignment problem, but with a complex objective function that makes it intractable for large problem instances. We present approximate models that can be used to provide upper and lower bounds on the optimal value, and also provide heuristic solution approaches that are able to successfully provide near-optimal solutions to a number of scenarios.

  • 23.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lundberg, Kristian
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Holmberg, Kaj
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Military aircraft mission planning: a generalized vehicle routing model with synchronization and precedence2013In: EURO Journal on Transportation and Logistics, ISSN 2192-4376, E-ISSN 2192-4384, Vol. 2, no 1-2, p. 109-127Article in journal (Refereed)
    Abstract [en]

    We introduce a military aircraft mission planning problem where agiven fleet of aircraft should attack a number of ground targets. Due to the nature of the attack, two aircraft need to rendez-vous at the target, that is, they need to be synchronized in both space and time. At the attack, one aircraft is launching a guided weapon, while the other is illuminating the target. Each target is associated with multiple attack and illumination options. Further, there may be precedence constraints between targets, limiting the order of the attacks. The objective is to maximize the outcome of the entire attack, while also minimizing the mission timespan. We give a linear mixed integer programming model of the problem, which can be characterized as ageneralized vehicle routing problem with synchronization and precedence side constraints. Numerical results are presented for problem instances of realistic size.

  • 24.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Van den Bergh, Jorne
    Katholieke University of Leuven, Belgium.
    Belien, Jeroen
    Katholieke University of Leuven, Belgium.
    A Time-Indexed Generalized Vehicle Routing Model and Stabilized Column Generation for Military Aircraft Mission Planning2015In: OPTIMIZATION, CONTROL, AND APPLICATIONS IN THE INFORMATION AGE: IN HONOR OF PANOS M. PARDALOSS 60TH BIRTHDAY, SPRINGER , 2015, Vol. 130, p. 299-314Conference paper (Refereed)
    Abstract [en]

    We introduce a time-indexed mixed-integer linear programming model for a military aircraft mission planning problem, where a fleet of cooperating aircraft should attack a number of ground targets so that the total expected effect is maximized. The model is a rich vehicle routing problem and the direct application of a general solver is practical only for scenarios of very moderate sizes. We propose a Dantzig-Wolfe reformulation and column generation approach. A column here represents a specific sequence of tasks at certain times for an aircraft, and to generate columns a longest path problem with side constraints is solved. We compare the column generation approach with the time-indexed model with respect to upper bounding quality of their linear programming relaxations and conclude that the former provides a much stronger formulation of the problem.

  • 25.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Using rolling horizon techniques in the planning process for a chemical process industry2014In: Pre-Prints, Vol.1, 18th International Working Seminars on Production Economics, Innsbruck, Austria, February 2014., 2014, p. 381-393Conference paper (Refereed)
    Abstract [en]

    We present a mathematical optimization model that can be used as a decision support tool for the supply chain planning at Perstorp Oxo AB, a global company in the process industry. At their site in Stenungsund, Perstorp Oxo AB produce chemicals to customers in a variety of branches and for further refinement at other Perstorp sites in Gent, Castellanza and Perstorp. The customers are mainly in branches such as food and feed, leather and textile, plastic and safety glass production. Since Perstorp Oxo sells products to customers worldwide, two large inventory facilities are located in Antwerp (Belgium) and Tees (United Kingdom) for five product types each and two smaller facilities in Philadelphia (USA) and Aveiro (Portugal) for one type respectively. The developed model is a mixed-integer linear program, where the objective function maximizes the profit. A solution to the model shows the quantities to be transported between the different sites, production rates, inventory levels, setups and purchases from external suppliers, each with its respective cost. Based on actual sales data from Perstorp Oxo AB, we use rolling horizon techniques to simulate how customer demands vary over a time horizon of one year, and show that our optimization model is able to find feasible and profitable production plans. The results show that there is a potential to increase profit margin by using a decision support tool based on an optimization model.

  • 26.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, Faculty of Science & Engineering.
    Ahlstedt, Mårten
    Linköping University.
    Olsson, Sven
    Linköping University.
    Supply Chain Modeling for a Process Industry2017In: International Journal of Operations Research and Information Systems, ISSN 1947-9328, Vol. 8, no 2, p. 36-55Article in journal (Refereed)
    Abstract [en]

    Process industries of today differ from other industries in many aspects. The purpose of this paper is to consider these special properties of process industries when developing a mathematical model that can be used as a decision support tool for the supply chain planning for a chemical process industry in Sweden. A mixed-integer linear programming model is developed, and solutions to the model present how the products will be transported between the different sites of the company, the levels of the inventories, the setups and purchases from the external suppliers and also the production rates. The mathematical model takes many special properties regarding process industries into account. By using the results from the model and test different scenarios, the model can be used as an important support tool when making decisions. The decision support tool can for example be used in the company's budget process and thereby improve the chances of future profits increases.

  • 27.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Ahlstedt, Mårten
    Linköping University, Department of Management and Engineering. Linköping University, The Institute of Technology.
    Olsson, Sven
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Supply Chain Planning at a Chemical Process Industry2013In: Proceedings for Decision Science Institute (DSI 2013), The 44th Annual Meeting, 2013, Decision Sciences Institute , 2013, p. 671895 - 1-671895 - 19Conference paper (Other academic)
    Abstract [en]

    The purpose of this paper is to develop a mathematical optimization model that can be used as a decision support tool for the supply chain planning at Perstorp Oxo AB, a global company in the process industry. At their site in Stenungsund, Perstorp Oxo AB produce chemicals to customers in a variety of branches and for further refinement at other Perstorp sites in Gent, Castellanza and Perstorp. The customers are mainly in branches such as food and feed, leather and textile, plastic and safety glass production. Since Perstorp Oxo sells products to customers worldwide, two large inventory facilities are located in Antwerp (Belgium)and Tees (United Kingdom) for five product types each and two smaller facilities in Philadelphia (USA) and Aveiro (Portugal) for one type respectively. The developed model is a mixed-integer linear program, where the objective function maximizes the profit margin, that is, the difference between the selling price and the cost of production, transportation, inventory carrying and outsourcing. A solution to the model shows the quantities to be transported between the different sites, production rates, inventory levels, setups and purchases from external suppliers, each with its respective cost. The results of a baseline scenario show that there is a potential to increase profit margin by using a decision support tool based on an optimization model.

  • 28.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lundberg, Kristian
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Holmberg, Kaj
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Aircraft Mission Planning2012Report (Other academic)
    Abstract [en]

    This paper deals with a Military Aircraft Mission Planning Problem, where the problem is to find time efficient flight paths for a given aircraft fleet that should attack a number of ground targets. Due to the nature of the attack, two aircraft need to rendezvous at the target, that is, they need to be synchronized in both space and time. At the attack, one aircraft is launching a guided weapon, while the other is illuminating the target. Each target is associated with multiple attack and illumination options. Further, there may be precedence constraints between targets, limiting the order of the attacks. The objective is to maximize the outcome of the entire attack, while also minimizing the mission time span. We present two mathematical models for this problem and compare their efficiency on some small test cases. We also provide some heuristic approaches since direct application of a general MIP solver to the mathematical model is only practical for smaller scenarios. The heuristics are compared and they successfully provide solutions to a number of scenarios.

  • 29.
    Quttineh, Nils-Hassan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Lundberg, Kristian
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Holmberg, Kaj
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Effect Oriented Planning2012Report (Other academic)
    Abstract [en]

    The problem setting concerns the tactical planning of a military operation. Imagine a big wide open area where a number of interesting targets are positioned. It could be radar stations or other surveillance equipment, with or without defensive capabilities, which the attacker wishes to destroy. Moreover, the targets are possibly guarded by defending units, like Surface-to-Air Missile (SAM) units. The positions of all units, targets and defenders, are known. We consider the problem of the attacker, where the objective is to maximize the expected outcome of a joint attack against the enemy, subject to a limited amount of resources (i.e. aircraft, tanks). We present a mathematical model for this problem, together with alternative model versions which provide optimistic and a pessimistic approximations. The model is not efficient for large problem instances, hence we also provide heuristic solution approaches and successfully provide solutions to a number of scenarios.

1 - 29 of 29
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