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  • 301.
    Erlandsson, Hampus
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Decision support for new travel center in Norrköping2015Independent thesis Basic level (university diploma), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    Beslutsunderlag för nya resecentrum Norrköping i samband med den nya järnvägen Ostlänken. Detta arbete utgör en del av det beslutsunderlag som Norrköpings kommun tagit fram i samband med det nya resecentrumet. Rapporten avhandlar uppbyggandet av en 3d-modell av resecentrumet i 3ds-max samt enkel visualisering i Lumion 3D. Arbetet avhandlar också användandet av interaktiv visualisering som en del av tidig planeringsprocess. Interaktiv visualisering innebär att modeller byggs upp på plats istället för att bollas mellan parter Användandet av interaktiv visualisering har positiva effekter på bland annat samarbete, interaktion mellan beställare och konsulter samt för inlevelsen i hur olika designer påverkar rummet. Det sparar även tid genom att beslut om ett förslag kan tas snabbare än om man skulle bolla förslag mellan parter. Den lindrar också inlåsningseffekter, att man fastnar i en design. Tidiga modeller gör det också lättare för konsulter att tolka olika förslag och som ett komplement till traditionella 2d-ritningar.

  • 302.
    Ernestus, Maximilian
    et al.
    TU Braunschweig, Germany.
    Friedrichs, Stephan
    Max Planck Institute Informat, Germany; Saarbrucken Grad School Comp Science, Germany.
    Hemmer, Michael
    TU Braunschweig, Germany.
    Kokemueller, Jan
    TU Braunschweig, Germany.
    Kroeller, Alexander
    TU Braunschweig, Germany.
    Moeini, Mahdi
    Technical University of Kaiserslautern, Germany.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Algorithms for art gallery illumination2017In: Journal of Global Optimization, ISSN 0925-5001, E-ISSN 1573-2916, Vol. 68, no 1, p. 23-45Article in journal (Refereed)
    Abstract [en]

    The art gallery problem (AGP) is one of the classical problems in computational geometry. It asks for the minimum number of guards required to achieve visibility coverage of a given polygon. The AGP is well-known to be NP-hard even in restricted cases. In this paper, we consider the AGP with fading (AGPF): A polygonal region is to be illuminated with light sources such that every point is illuminated with at least a global threshold, light intensity decreases over distance, and we seek to minimize the total energy consumption. Choosing fading exponents of zero, one, and two are equivalent to the AGP, laser scanner applications, and natural light, respectively. We present complexity results as well as a negative solvability result. Still, we propose two practical algorithms for AGPF with fixed light positions (e.g. vertex guards) independent of the fading exponent, which we demonstrate to work well in practice. One is based on a discrete approximation, the other on non-linear programming by means of simplex-partitioning strategies. The former approach yields a fully polynomial-time approximation scheme for the AGPF with fixed light positions. The latter approach obtains better results in our experimental evaluation.

  • 303.
    Errasti, Ander
    et al.
    Natra Grp, Spain.
    Rudberg, Martin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Corti, Donatella
    University of Appl Science and Arts Southern Switzerland, Switzerland.
    Editorial Material: Managing international operations: configuration of production network for SMEs in PRODUCTION PLANNING and CONTROL, vol 26, issue 9, pp 691-6922015In: Production planning & control (Print), ISSN 0953-7287, E-ISSN 1366-5871, Vol. 26, no 9, p. 691-692Article in journal (Other academic)
    Abstract [en]

    n/a

  • 304.
    Errasti Opacua, Ander
    et al.
    University of Navarra, Spain.
    Medibil, Kepa
    University of Strathclyde, Scotland, UK.
    Rudberg, Martin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Baines, Tim
    Aston Business School, England, UK.
    Operations Strategy and Deployment2011In: International Manufacturing Networks: Global Operations Design and Management / [ed] Ander Errasti Opacua, San Sebastian: Eusko Jaurlaritzaren , 2011, 500, p. 67-94Chapter in book (Other academic)
    Abstract [en]

    This paper seeks to extend existing manufacturing system concepts and develop new structured knowledge about international manufacturing networks by analysing the networks, classifying the configurations and identifying the capabilities. The design and operation of international manufacturing networks is an increasingly important issue for transnational corporations faced with rapid changes in global market opportunity, competition and new managerial mechanisms. Four international manufacturing networks in mechanical and process industries are analysed and a number of conclusions drawn: first, a novel configuration map is proposed; second, key strategic capability parameters are identified; third, networking trends and their implications for configuration are discussed. Finally, the paper explores strengths and weaknesses of the particular methodology adopted in this research.

  • 305.
    Falk, Matilda
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Hedkrok, Sabina
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Coordination of the information and material flow of lego products - A case study at Siemens Industrial Turbomachinery AB2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Studien betraktar informations- och materialflödet för legomaterial på Siemens Industrial Turbomachinery AB i Finspång. Det studerade problemet gäller att det finns en dålig uppfattning bland de anställda om hur flödet och arbetet med lego ser ut, samt dålig kommunikation mellan de inblandade avdelningarna. Genom intervjuer med ansvariga för legomaterialsamt granskning av tidigare dokument har legoflödet kunnat beskrivas. Problematiken på företaget har studerats utifrån teori kring processer och flöden samt kommunikation, integration och koordinering Rapporten presenterar en samordnad bild över arbetet med legomaterial genom en kartläggning med tillhörande flödesschema över informations- och materialflödet för lego inom företaget. I studien har problem med koordination och samarbetet mellan de inblandade avdelningarna identifierats. Rapporten följs upp med förslag på åtgärder och vidare arbete för att lösa problemen.

  • 306.
    Falkman, Anton
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Myöhänen, Sebastian
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Comparative study of joists for a industrial building2016Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Syftet med denna studie är att avgöra om ett stål- eller betongbjälklag lämpar sig bäst för industribyggnaden sett ur ett konstruktions- och ekonomiskt perspektiv. Rapporten är även tänkt att kunna fungera som ett hjälpmedel för blivande ingenjörer eller andra personer som beräknar och analyserar liknande konstruktioner. I rapporten har vi två stycken frågeställningar, hur ett mellanbjälklag bör utformas och vilka faktorer som är avgörande. För att svara på dem använder vi oss av kvantitativa metoder. Rapporten är uppbyggd på relevant litteratur som har behandlats och gett oss en grund att stå på. Med hjälp av denna litteratur har vi sedan utfört beräkningar, analyserat, tolkat och diskuterat. De resultat som vi kommer fram till i rapporten är att båda de olika typerna av mellanbjälklag klarar boverkets krav och båda materialen skulle kunna användas för att konstruera mellanbjälklaget i den aktuella industribyggnaden om så önskas. Båda bjälklagen i stål respektive betong har sina materialspecifika för- och nackdelar. Betong är ett billigare material och har ett bra brandskydd utan att någon extra behandling behövs. Å andra sidan väger betong mer och kräver större dimensioner. Stål är lättare och kan utföras i mindre dimensioner, det finns även fungerande brandskydd för stål, dock måste den appliceras separat, antingen genom brandskyddsfärg eller genom överdimensionering. Slutsatser och rekommendationer är att båda materialen kan användas som mellanbjälklag för byggnaden i fråga. Den avgörande faktorn blir helt klart den ekonomiska aspekten då betong är betydligt billigare än stål. Rekommendationen blir därmed att mellanbjälklaget byggs i betong.

  • 307.
    Fekete, Sandor P.
    et al.
    TU Braunschweig, Germany.
    Haas, Andreas
    TU Braunschweig, Germany.
    Hemmer, Michael
    TU Braunschweig, Germany.
    Hoffmann, Michael
    Swiss Federal Institute Technology, Switzerland.
    Kostitsyna, Irina
    TU Eindhoven, Netherlands.
    Krupke, Dominik
    TU Braunschweig, Germany.
    Maurer, Florian
    TU Braunschweig, Germany.
    Mitchell, Joseph S. B.
    SUNY Stony Brook, NY 11794 USA.
    Schmidt, Arne
    TU Braunschweig, Germany.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Troegel, Julian
    TU Braunschweig, Germany.
    Computing Nonsimple Polygons of Minimum Perimeter2016In: EXPERIMENTAL ALGORITHMS, SEA 2016, SPRINGER INT PUBLISHING AG , 2016, Vol. 9685, p. 134-149Conference paper (Refereed)
    Abstract [en]

    We provide exact and approximation methods for solving a geometric relaxation of the Traveling Salesman Problem (TSP) that occurs in curve reconstruction: for a given set of vertices in the plane, the problem Minimum Perimeter Polygon (MPP) asks for a (not necessarily simply connected) polygon with shortest possible boundary length. Even though the closely related problem of finding a minimum cycle cover is polynomially solvable by matching techniques, we prove how the topological structure of a polygon leads to NP-hardness of the MPP. On the positive side, we show how to achieve a constant-factor approximation. When trying to solve MPP instances to provable optimality by means of integer programming, an additional difficulty compared to the TSP is the fact that only a subset of subtour constraints is valid, depending not on combinatorics, but on geometry. We overcome this difficulty by establishing and exploiting additional geometric properties. This allows us to reliably solve a wide range of benchmark instances with up to 600 vertices within reasonable time on a standard machine. We also show that using a natural geometry-based sparsification yields results that are on average within 0.5% of the optimum.

  • 308.
    Fekete, Sándor P.
    et al.
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Haas, Andreas
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Hemmer, Michael
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Hoffmann, Michael
    Department of Computer Science, ETH Zürich, Zürich, Switzerland.
    Kostitsyna, Irina
    Department of Mathematics and Computer Science, TU Eindhoven, Eindhoven, The Netherlands.
    Krupke, Dominik
    Department of Computer Science, TU Braunschweig, Braunschweig, GermanyDepartment of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Maurer, Florian
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Mitchell, Joseph S.B.
    Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, USA.
    Schmidt, Arne
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Troegel, Julian
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Computing Nonsimple Polygons of Minimum Perimeter2017In: Journal of Computational Geometry (JoCG), ISSN 1920-180X, Vol. 8, no 1Article in journal (Refereed)
    Abstract [en]

    We consider the Minimum Perimeter Polygon Problem (MP3): for a given set V of points in the plane, find a polygon P with holes that has vertex set V , such that the total boundary length is smallest possible. The MP3 can be considered a natural geometric generalization of the Traveling Salesman Problem (TSP), which asks for a simple polygon with minimum perimeter. Just like the TSP, the MP3 occurs naturally in the context of curve reconstruction. Even though the closely related problem of finding a minimum cycle cover is polynomially solvable by matching techniques, we prove how the topological structure of a polygon leads to NP-hardness of the MP3. On the positive side, we provide constant-factor approximation algorithms. In addition to algorithms with theoretical worst-case guarantess, we provide practical methods for computing provably optimal solutions for relatively large instances, based on integer programming. An additional difficulty compared to the TSP is the fact that only a subset of subtour constraints is valid, depending not on combinatorics, but on geometry. We overcome this difficulty by establishing and exploiting geometric properties. This allows us to reliably solve a wide range of benchmark instances with up to 600 vertices within reasonable time on a standard machine. We also show that restricting the set of connections between points to edges of the Delaunay triangulation yields results that are on average within 0.5% of the optimum for large classes of benchmark instances. 

  • 309.
    Felixon, William
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A case study which aims to streamline Tretti's receiving process by improving the suppliers' delivery processes2016Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [sv]

    Tretti AB är ett e-handelsföretag som säljer produkter inom segmenten vitvaror, hushållsapparater, hem och trädgård, personvård, badrum samt sport och fritid. För företag som är verksamma inom e-handel innebär logistik flera konkurrensfaktorer. Kunderna kräver exempelvis låga leveranstider och framförallt att utlovade leveranstider hålls. Det finns även också goda möjligheter att bli kostnadseffektiv gentemot konkurrenter genom att hela tiden ligga i framkant och utveckla sitt logistiksystem.

    Ankomstprocessen är en kritisk process i ett företags logistikflöde. Främst p.g.a. att den är beroende av leverantörernas leveransprocesser. Undermålig leveransservice av leverantörerna kan leda till långdragna och kostsamma mottagningsprocesser hos kunderna.

    Tretti såg en potentiell utvecklingsmöjlighet i deras ankomstprocess. Som ett första steg i att försöka effektivisera ankomstprocessen ville Tretti undersöka möjligheterna att förbättra leverantörernas leveransservice. Syftet med denna studie är således att genom att skapa en förståelse för hur och på vilket sätt leverantörernas leveransservice påverkar Trettis ankomstprocess föreslå förbättringsförslag som ifall de implementeras leder till en effektivisering av ankomstprocessen.

    För att uppnå syftet behövdes en förståelse skapas för vilka aktiviteter som ingår i ankomstprocessen samt hur de förhåller sig till varandra. Detta gjordes genom att observera Trettis ankomstprocess. För att sedan få en förståelse för vilka aktiviteter i ankomstprocessen som påverkas av leverantörernas leveransservice gjordes intervjuer av anställda i godsmottagningen. En analys av både observationerna och intervjuerna resulterade i en lista med kritiska delar i ankomstprocessen. Om leverantörerna inte presterar tillräckligt bra i sin leveransservice påverkar det dessa kritiska delar negativt och det gör att ankomstprocessen blir långdragen och kostsam.

    Exempel på kritiska delar är ingen individuell kolliuppmärkning, layout på följesedel och leveranser utan följesedel. En jämförelse av två leveranser från två olika leverantörer gjordes under observationerna. En av leverantörerna arbetade med individuell kolliuppmärkning vilket resulterade i en bättre layout på följesedeln. Denna leverantör hade en individuell följesedel på varje kolli som specificerade vad den pallen eller kartongen innehöll. Den andra leverantören samlade hela leveransen i en gemensam följesedel vilket ledde till en lång och ostrukturerad följesedel. Vissa leveranser från denna leverantör hade en 18 sidor lång följesedel. Att en leverantör samlade hela leveransen i en följesedel innebar således att det inte specificerades vad varje individuellt kolli eller kartong innehöll. Jämförelsen visade att leveranserna från leverantören som arbetade med följesedlar som specificerade vad varje kartong eller pall innehöll resulterade i att ankomstprocessen blev effektivare, framförallt för att varje kolli kunde tas emot individuellt. Ankomstprocessen blev mer tidskrävande vid leveranser från leverantören som hade en följesedel per leverans bl.a. för att det krävdes att samtliga kollin i leveransen lokaliserades innan ankomstregistreringen kunde påbörjas, ibland upp emot 40 pallar, samt att det tog längre tid att para ihop en artikelrad på följesedeln med den fysiska artikeln.

    Sista steget för att uppfylla syftet blev att konkret formulera lösningsförslag som vid implementering leder till en effektivare ankomstprocess. Ett lösningsförslag föreslår en implementering av ett standardiserat system för företags värdekedjor utvecklat av den ickevinstdrivande organisationen GS1. Detta system ger varje individuellt kolli en streckkod som samlar information om kollit. Vid skanning av streckkoden kan information om vilka  artiklar kollit innehåller hämtas och syftet är att med detta system i större utsträckning standardisera Trettis ankomstprocess. Ett annat lösningsförslag är att formulera en kravspecifikation för samtliga leverantörer som tydligt klargör vad som förväntas av leverantörer till Tretti.

  • 310.
    Fellenius, Beatriz
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Mapping and evaluation of the purchasing process at Ahlvar2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Modebranschen är en ständigt föränderlig bransch som präglas av långa ledtider, osäkra prognoser och starkt trendfokus. Ahlvar By Frida Ahlvarsson är ett svenskt modeföretag som verkar inom just denna bransch. Ahlvar upplever precis som många andra små modeföretag problem kopplade till branschens uppbyggnad. Problemen som företaget upplever är främst ekonomiska men har också att göra med höga lagernivåer och hög arbetsbelastning. I detta arbete görs en granskning av Ahlvars inköpsprocess med hjälp av Business Process Management (BPM) för att identifiera orsakerna bakom de problem som företaget upplever. Det fastslås att företagets ekonomiska problem främst är kopplade till höga produktionskostnader medan de höga lagernivåerna främst beror på avsaknaden av statistiska prognoser. Den höga arbetsbelastningen verkar i sin tur ha att göra med det faktum att det som enmansföretag är svårt att handskas med inköpsprocessens många steg och parallella processer. För att identifiera lösningar till dessa problem presenteras teori kring inköpsprocesser och även information om hur tre liknande modeföretag arbetar. De tre andra företagen är Filippa K, Företag X och House of Dagmar. Tillsammans med teorin görs en jämförelse mellan dessa tre och Ahlvar. Jämförelsen visar att det finns många likheter mellan företagen och att mycket av deras arbetssätt har goda kopplingar till teorin. Dock i identifieras även vissa markanta skillnader mellan Ahlvar och de andra företagens arbetssätt. Utifrån jämförelsen fastslås tre huvudsakliga rekommendationer för hur Ahlvar ska förändra sin inköpsprocess i syfte att förbättra sin ekonomiska situation med hjälp av en mer effektiv försörjningskedja. Rekommendationerna är att företaget bör hitta fler leverantörer, byta leverantörsland från Kina till ett eller flera länder i Europa och att börja göra enklare prognoser på tidigare års försäljning. Som en följd av bytet av leverantörsland rekommenderas även företaget att förändra sitt val av transportslag från flygplan till lastbil och båt vid frakt av produkter.

  • 311.
    Fingal, Ida
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lundström, Frida
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Improvement of Drug Handling with Lean2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Vårdcentralen Cityhälsan Centrum i Norrköping upplever stora svårigheter och problem kring läkemedelshanteringen för patienter som nyttjar dosdispenseringstjänsten ApoDos. Problemen anses av personalen ha eskalerat sedan sommaren 2012, när det nya IT-verktyget Pascal för läkemedelsordinering infördes. Flera yrkesgrupper inom vårdcentralen berörs av arbetet med ApoDos och är på olika sätt delaktiga i arbetet som följer då en patient ska anslutas till dostjänsten. Ingen av de involverade yrkesgrupperna vet vad som orsakar problemen eller var dessa uppstår. Examensarbetet syftar därför till att kartlägga flödet då en hemsjukvårdspatient ansluts till dosdispenseringstjänsten ApoDos, för att sedan identifiera problemområden och föreslå förbättringar. Examensarbetet har utförts på uppdrag av Cityhälsan Centrum och intervjuer och observationer har gjorts med såväl vårdcentralens anställda som den tillhörande hemsjukvårdspersonalen. Resultatet av intervjuer och litteraturstudier är en kartläggning av det ideala flödet och det faktiska flödet. Båda flödena startar då beslut om att en patient ska anslutas till ApoDos tas och slutar då patienten har sina läkemedel i hemmet. Utifrån jämförelse mellan dessa flöden och efter genomförande av ytterligare intervjuer har problemområden sedan identifierats. Problemen har observerats och de aktuella yrkesgrupperna för respektive problem har intervjuats, varefter åtgärdsförslag arbetats fram. Dessa har tagits fram med stöd från den valda teoretiska referensramen Lean, och för varje problem har slöserier identifierats och metoder för att minska eller eliminera dessa har presenterats. Resultatet är en identifiering av var i flödet problem uppstår och vad som orsakar dessa. Problem har främst funnits de delar av flödet som på något sätt är kopplat till IT-verktyget Pascal. En analys och diskussion har förts över möjliga, vidtagbara åtgärder för Cityhälsan Centrum, och dessa handlar främst om standardisering, skapa en ökad förståelse för arbetet, eliminera icke värdeskapande aktiviteter och att göra rätt från början. Cityhälsan Centrum ska med hjälp av resultatet och analysen själva kunna genomföra de förslagna åtgärderna och då uppnå en tidsbesparing eller en förenkling av aktiviteter som ingår i flödet. Om de väljer att genomföra föreslagna åtgärder skulle det även kunna leda till ett snabbare förlopp från det att patienten önskar bli ansluten till ApoDos till dess att denne får sina påsar levererade.

  • 312.
    Fitzthum, Anton
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Simulation of rerouting incentives for improved travel corridor performance2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Congestion on the road is identified as a severe threat to nations’ economy. To address this problem, in the past the capacity of existing infrastructure is increased by building new roads. But as history has shown, it is not only an expensive and unsustainable, but also not an efficient way of dealing with this problem. Alternatively, by identifying underutilized links, for example, in the form of parallel routes, the already existing infrastructure can often be used more efficient.

    This thesis focuses on the development of a framework to simulate re-routing incentives to enable an improved travel corridor performance. Thus, the effects of providing traveler information and tendering mometary incentives on a concidor’s traffic flow are investigated. The aim is to show that by changing the route choice behavior of a certain percentage of the fleet, the overall performance of the existing corridor can be increased.

    By using the microscopic traffic simulation tool VISSIM in combination with dynamic traffic modeling, numerous scenarios are simulated. By gradually increasing the amount of users who get access to the incentive scheme, the impacts of the penetration get analyzed as well. Based on a network stretch located in California, United States, the simulation model is developed. Using this model, three different scenarios are investigated in detail: a No Incident scenario, a Construction Work scenario and an Accident scenario.

    Finally, a comprehensive analysis of the simulation results takes place. It mainly focuses on the indicator travel time to discuss the impacts on the corridor performance. Interpreting the achieved simulation results, it can be stated that already small penetration rates have the potential for a significant increase of the corridor performance. To be able to optimize the corridor’s performance, free capacity on detours – especially  at bottlenecks like ramps – has to be available. Nevertheless, in case of high penetration rates, straightforward broadcasting of incentives is not an option.

  • 313.
    Forsberg, Lucas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Ström, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    An analysis of schedule buffer time for increased robustness and cost efficiency in Scandinavian Airlines´traffic program2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The airline industry has become more competitive since the introduction of low fare airlines in the 1990s. Thus, requirement of optimized planning is nowadays essential in order to obtain high market shares. The planning behind an airworthy traffic program is complex and includes many different resources, as fleet, crew and maintenance, which have to be synchronized. With a constant risk of unforeseen disruptions and variances in the weather conditions, robustness in form of time buffers are necessary in order to give the system a chance of recovery. Generally, one delay often affects several flights due to the lack of time buffers. In order to achieve cost reductions and to maximize profit, airlines tends to create traffic programs maximizing airborne hours. This report culminates in a conclusion of where and when time buffers, in a cost efficient way, can be added in Scandinavian Airline´s traffic program in order to obtain a higher robustness. This is performed by analyzing historical flight data and by implementing a Monte Carlo simulation.

  • 314.
    Forsberg, Martin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Dimensioning of concrete walls against cleavage under concentrated loads2015Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sprickor i betongkonstruktioner kan ha en förödande effekt på konstruktioners säkerhet och stabilitet, men kan även göra att det blir en oangenäm syn att kolla på. Dessa sprickor orsakas utav dragspänningar i betongen som kan uppkomma som konsekvenser från olika typer av laster. Denna rapport fokuserar på spänningar orsakade utav en koncentrerad belastning på betongväggar. Syftet är att se hur spjälksprickor uppkommer och vilka åtgärder man kan göra mot detta med hjälp av armeringsbyglar eller armeringsstegar i betongväggar. Detta gör att målet blir att skapa en smidig beräkningsgång för att undersöka hur mycket armering som krävs och även se hur armeringsstegar kan användas för detta ändamål. För att ställa upp beräkningar så har fackverksanalogin använts och kraftspridningen har grund i kraftlinjemetoden för att denna metod ger en bra spegling av hur krafterna kommer att spridas i konstruktionens diskontinuitetszoner. Resultatet är en beräkningsgång av kontroller om det finns risk för att spjälkning och prägling förekommer och framtagandet av den erforderliga spjälkarmeringarea som behövs vid en koncentrerad last och hur denna ska placeras när risken finns. Armeringsstegar i skalväggar är inte att rekommendera för att de har en liten diameter och utbredningshöjden gör att det krävs många stegar för att klara av krafterna.

  • 315.
    Forsberg, Veronica
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    VSM for a car dealer2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    På Söderbergs Personbilar i Norrköping AB bedrivs en serviceprocess för begagnade bilar, en tjänsteverksamhet som idag är präglad av en stor ineffektivitet med avseende på tid. I detta examensarbete utförs en fallstudie på företaget där problemet analyseras i syfte att identifiera det tidssvinn som förekommer i processen, utreda dess uppkomst, samt formulera passande åtgärdsförslag till företaget som vid ett genomförande skulle minska genomloppstiden för bilarna i processen. Intervjuer och observationer har skapat en övergripande förståelse för processen, där förklaringar har erhållits om hur processen är tänkt att fungera, hur den fungerar i praktiken, och varför den fungerar som den gör. Som komplement till detta har värdeflödeskartläggning av två bilar genomförts, där bilarnas färd genom processen studerades i praktiken. De två bilarna studerades från dess inkommande till företaget tills det att de var klara till försäljning. Genom detta erhölls ytterligare information om processen. I värdeflödeskartläggningen framkom det att tidssvinnet var stort för bägge bilar, och att andelen tid för värdehöjande aktiviteter var mycket liten för bilarna. Allt material om processen analyseras och ett antal olika åtgärdsförslag för processen är framarbetade till företaget. Tre huvudåtgärder presenteras som vid ett införande troligen skulle underlätta avsevärt för företaget vid ett genomförande av övriga åtgärdsförslag. Den första av dessa tre huvudåtgärder är att tillsätta en ledare för processen, något som saknas idag. Ledaren ska ha befogenheter att genomföra förändringar i processen, och ska arbeta för en ständig förbättring av processen. Den andra huvudåtgärden är att utveckla nedskrivna standarder för personalen som beskriver hur alla aktiviteter inom processen ska utföras. Standarderna ska vara utformade så att aktiviteterna utförs på ett optimalt sätt. Den tredje huvudåtgärden är att göra fler resurser dedikerade inom processen. Dessa tre åtgärder, och övriga åtgärdsförslag skulle med största sannolikhet generera en avsevärt kortare genomloppstid för bilarna, det vill säga precis det resultat som eftersöks i processen.

  • 316.
    Fossum, Benjamin
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Hedborg, Johan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Resource management analysis at the prehospital emergency care unit in north-western Skåne2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to investigate the preparedness at the prehospital emergency care unit in north-western Skåne. Measuring preparedness is important to ensure that the ability to respond on emergency calls is satisfactory. To do this for north-western Skåne historical data from 2015 was extracted from SOS Alarm’s database. It was used to calculate preparedness using workload and coverage as measurements. The workload was calculated by taking the busy periods and comparing them to the ambulances working times. The coverage was calculated by defining neighbouring stations to cover for each station and then finding the amount of hours when there was no ambulance at either station. These calculations show that two of the six stations in north-western Skåne are in need of improvement. To increase the preparedness to a good level resources will have to be added at the liable stations. These resources would be new ambulances. There is a possibility to relocate ambulances from stations within the district but that would lead to a worsened preparedness for the stations which these ambulances belonged to in the first place.

  • 317.
    Fountoulakis, Emmanouil
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Liao, Qi
    Nokia Bell Labs, Germany.
    Suryaprakash, Vinay
    Nokia Bell Labs, Germany.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    An Examination of the Benefits of Scalable TTI for Heterogeneous Traffic Management in 5G Networks2017In: 2017 15TH INTERNATIONAL SYMPOSIUM ON MODELING AND OPTIMIZATION IN MOBILE, AD HOC, AND WIRELESS NETWORKS (WIOPT), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    The rapid growth in the number and variety of connected devices requires 5G wireless systems to cope with a very heterogeneous traffic mix. As a consequence, the use of a fixed transmission time interval (TTI) during transmission is not necessarily the most efficacious method when heterogeneous traffic types need to be simultaneously serviced. This work analyzes the benefits of scheduling based on exploiting scalable TTI, where the channel assignment and the TTI duration are adapted to the deadlines and requirements of different services. We formulate an optimization problem by taking individual service requirements into consideration. We then prove that the optimization problem is NP-hard and provide a heuristic algorithm, which provides an effective solution to the problem. Numerical results show that our proposed algorithm is capable of finding near-optimal solutions to meet the latency requirements of mission critical communication services, while providing a good throughput performance for mobile broadband services.

  • 318.
    Fowler, Scott
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Study on Power Saving Based on Radio Frame in LTE Wireless Communication System Using DRX2011Conference paper (Refereed)
    Abstract [en]

    Long Term Evolution (LTE) of 3GPP provides high bandwidth for data transfer. Having high bandwidth transfer will exhaust the user equipment (UE)'s battery power quickly. To extend the UE's battery lifetime the 3GPP standards for LTE support Enhanced Discontinuous Reception (DRX). The DRX allow an idle UE to save battery by turning off the radio receiver for a predefined period. Since the Transmission Time Interval (TTI) is related to the size of the data block passed from the higher networks layers to the radio link layer, the DRX scheduler should vary the resource allocation of each user basis on TTI. In this paper, we have evaluated the influences of the TTI sizes as well as the effects of LTE DRX Light and Deep Sleep mode on power consumption for Voice and Web traffic.

  • 319.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Formulation of Path Selection by means of maximum flow and minimum delay on a Free Space Optical Topology2016In: 2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    Wireless radio-frequency (RF) technologies has had universal wide-scale deployment. Despite this, the practical limitations of the RF spectrum being unable to meet the challenges (e.g. lack of security, high interference, limited bandwidth, scalability) of RF based communication networks have become increasingly apparent over the past decade. With the evergrowing of data heavy wireless communications, especially on the last mile (e.g. wireless mesh network) and the backbone, methods are required to help addresses the problem RF have been facing for the next generation network. Faced with such daunting obstacles in RF-only networks, the use of Free Space Optical (FSO) for wireless communications was proposed. FSO is a promising solution to security, limited spectrum bandwidth, the scalability problem of wireless mesh networks, but also the advantage of large transmission distance, free license, interference immunity, and high-bandwidth. Despite the major advantages of FSO technology, its widespread use has been hampered by atmospheric turbulence-induced fading. However, FSO is still consider to be a practical solution to RF challenges. To maximize the potential of FSO networks, we study the problem of maximum path resource flow for a route and minimum linear delay while the FSO topology under atmospheric turbulence. Such methods can be easy adopted to SDN to manage the data flow at the linkor network-layer.

  • 320.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Numerical analysis of an industrial power saving mechanism in LTE2014In: Communications (ICC), 2014 IEEE International Conference on, IEEE conference proceedings, 2014, p. 1748-1753Conference paper (Refereed)
    Abstract [en]

    The 4G standard Long Term Evolution (LTE) utilizes discontinuous reception (DRX) to extend the user equipments battery lifetime. DRX permits an idle UE to power off the radio receiver for two predefined sleep period and then wake up to receive the next paging message. Two major basic power saving models proposed to data are the 3GPP ETSI model and industrial DRX model proposed by Nokia. While previous studies have investigated power saving with the 3GPP ETSI models, the industrial DRX model has not been considered for analytical studies to date. Thus, there is a need to optimize the DRX parameters in the industrial model so as to maximize power saving without incurring network reentry and packet delays. In this paper, we take an overview of various static DRX cycles of the LTE/LTE-Advanced power saving mechanisms by modelling the system with bursty packet data traffic using a semi-Markov process. Using this analytical model, we will show the tradeoff relationship between the power saving and wake-up delay performance in the industrial model.

  • 321.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Bhamber, Ranjeet S.
    Instituto deOptica ''Daza de Valdés.
    Mellouk, Abdelhamid
    University of Paris-Est Creteil (UPEC).
    Analysis of adjustable and fixed DRX mechanism for power saving in LTE/LTE-Advanced2012In: 2012 IEEE International Conference on Communications (ICC), IEEE , 2012, p. 1964-1969Conference paper (Refereed)
    Abstract [en]

    The 4G standard Long Term Evolution (LTE) has been developed for high-bandwidth mobile access for today's data-heavy applications, consequently, a better experience for the end user. To extend the user equipment battery lifetime, plus further support various services and large amount of data transmissions, the 3GPP standards for LTE/LTE-Advanced has adopted discontinuous reception (DRX). However, there is a need to optimize the DRX parameters, so as to maximize power saving without incurring network re-entry and packet delays. In this paper, we take an overview of the fixed frame DRX cycle and compare it against an adjustable DRX cycle of the LTE/LTE-Advanced power saving mechanism, by modelling the system with bursty packet data traffic using a semi-Markov process. Based on the analytical model, we will show the trade-off relationship between the power saving and wake-up delay performance.

  • 322.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Hameseder, Katrin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    An Empirical Evaluation of Web System Access for Smartphone Clients2012In: Journal of Networks, ISSN 1796-2056, E-ISSN 1796-2056, Vol. 7, no 11, p. 1700-1713Article in journal (Refereed)
    Abstract [en]

    As smartphone clients are restricted in computational power and bandwidth, it is important to minimise the overhead of transmitted messages.  This paper identifies and studies methods that reduce the amount of data being transferred via wireless links between a web service client and a web service. Measurements were performed in a real environment based on a web service prototype providing public transport information for the city of Hamburg in Germany, using actual wireless links with a mobile smartphone device.  REST based web services using the data exchange formats JSON, XML and Fast Infoset were evaluated against the existing SOAP based web service.

  • 323.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Häll, Carl Henrik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Mellouk, Abdelhamid
    University of Paris-Est Creteil VdM (UPEC), France.
    Analysis of vehicular wireless channel communication via queueing theory model2014In: Communications (ICC) 2014 IEEE International Conference on Communications, IEEE , 2014, p. 1736-1741Conference paper (Refereed)
    Abstract [en]

    The 4G standard Long Term Evolution (LTE) has been developed for high-bandwidth mobile access for today's data-heavy applications, consequently, a better experience for the end user. Since cellular communication is ready available, LTE communication has been designed to work at high speeds for vehicular communication. The challenge is that the protocols in LTE/LTE-Advanced should not only provide good packet delivery but also adapt to changes in the network topology due to vehicle volume and vehicular mobility. It is a critical requirement to ensure a seamless quality of experience ranging from safety to relieving congestion as deployment of LTE/LTE-Advanced become common. This requires learning how to improve the LTE/LTE-Advanced model to better appeal to a wider base and move toward additional solutions. In this paper we present a feasibility analysis for performing vehicular communication via a queueing theory approach based on a multi-server queue using real LTE traffic. A M/M/m model is employed to evaluate the probability that a vehicle finds all channels busy, as well as to derive the expected waiting times and the expected number of channel switches. Also, when a base station (eNB) becomes overloaded with a single-hop, a multi-hop rerouting optimization approach is presented.

  • 324.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Li, Yuan
    Dept. of Electrical and Information Technology, Lund University, Sweden.
    Pollastro, A.
    MobiMESH, Milano srl, Italy.
    Napoli, S.
    MobiMESH, Milano srl, Italy.
    Simple network design and power allocation for 5G device-to-device communication2014In: Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), 2014 IEEE 19th International Workshop on, IEEE conference proceedings, 2014, p. 203-207Conference paper (Refereed)
    Abstract [en]

    The tremendous popularity of smart phones and electronic tablets has spurred the explosive growth of high-rate multimedia wireless services. To alleviate the huge infrastructure investment in the exponential growth of mobile traffic and improve local service flexibility, device-to-device (D2D) communications have been considered for the next generation mobile telecommunications. This has triggered investigation of fifth gernation (5G) to utilizes D2D communications for hetergenous networks. D2D communications enable users to transmit signals directly without going through the base station. However, many technical challenges need to be addressed for D2D communications to harvest the potential benefits. This requires learning how to improve the the model to better appeal to a wider base and move toward additional solutions. In this paper we provided a simple overview of D2D communications 5G hetergenous network by means of various Integer Linear programming. Finally, we present experiments on how Fractional knapsack using greedy algorithm can be used for power efficiency and improve throughput, thus allowing of future optimization problems.

  • 325.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Sarfraz, Jalal
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Abbas, M. Muddassir
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Bergfeldt, Erik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Evaluation and prospects from a measurement campaign on real multimedia traffic in LTE vs. UMTS2014In: Wireless Communications, Vehicular Technology, Information Theory and Aerospace Electronic Systems (VITAE'14), IEEE 4th International Conference on, IEEE Press, 2014, p. 1-5Conference paper (Refereed)
    Abstract [en]

    The LTE standard has been developed for high-bandwidth mobile access for today’s data-heavy applications. With broadband cellular available already from the UMTS system, users are expecting the LTE network to provide high quality communication. To ensure the quality and correctness of complex systems of LTE, it is important to evaluate the behavior of traffic on a LTE network in relation to UMTS. In this paper, LTE and UMTS measurements on video traffic were performed in a real environment, allowing for greater development, and understanding of network traffic performance.

  • 326.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Sarfraz, Jalal
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Abbas, Muhammad Muddassir
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Gaussian semi-Markov Model based on Real Video Multimedia Traffic2015In: IEEE International Conference on Communications Communications (ICC) 2015 / [ed] IEEE, IEEE Press, 2015, p. 6971-6976Conference paper (Refereed)
    Abstract [en]

    The 3rd Generation Partnership Project (3GPP) introduced the new radio access technology, LTE (Long Term Evolution) and LTE-Advanced, which has the capability to provide larger bandwidth and low latencies on a wireless network in order to fulfill the demand of Users' Equipment (UEs) with acceptable Quality of Service (QoS). One of the data-heavy applications that has exploded on the market is Video. This calls for accurate modeling of video traffic. To ensure the quality and correctness of complex systems with Video traffic, it is important to evaluate the behavior of the traffic in the heterogeneous environment. This paper presents measurements on LTE Video traffic which were performed in a real environment. We derived a semi-Markov model which accurately reproduces the statistics of composite Video measurements over LTE network.

  • 327.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Shahidullah, Ahmed Omar
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Osman, Mohammed
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Karlsson, Johan M.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Analytical evaluation of extended DRX with additional active cycles for light traffic2015In: The International Journal of Computer Networks (COMNET), Elsevier, ISSN 1389-1286, Vol. 77, p. 90-102Article in journal (Refereed)
    Abstract [en]

    Abstract LTE and LTE-Advanced mobile technologies have integrated discontinuous reception (DRX) power saving method to optimize the power consumption at the user equipment (UE). The DRX method was proposed by the 3rd Generation Partnership Project (3GPP), and since then, the traffic behavior has been analyzed in several studies with a standard 3-state DRX model to describe the trade-off between power saving and delay. In this paper, we presented a novel 4-state and 5-state 3GPP LTE DRX mechanisms. The proposed mechanisms were developed by augmenting (an) active state(s) to deep and/or light sleep cycle of standard 3-state DRX for handling a small burst of packets, thereby bypassing the process of returning to the timer-dependent active mode. We have generated analytical models using a semi-Markov process for bursty packet data traffic and evaluated these augmented DRX mechanisms against a standard 3-state DRX method. Overall, the analytical results from varying timing parameters showed that our augmented DRX (both 4-state and 5-state) improved power saving factor (ranging between 1% and 8%) and reduced delay (ranging between 20% and 60%) compared to the standard 3-state DRX. Furthermore, the magnitude of improvement for both delay and power-saving was somewhat greater in 5-state than 4-state.

  • 328.
    Fowler, Scott
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Zhang, Xingjun
    Department of Computer Science, Xi’an Jiaotong University, China.
    Ubiquitous Fair Bandwidth Allocation for Multimedia Traffic on a WiMAX Mesh Network with Multi-channels2012In: International Journal of Ad Hoc and Ubiquitous Computing, ISSN 1743-8225, E-ISSN 1743-8233, Vol. 9, no 4, p. 224-240Article in journal (Refereed)
    Abstract [en]

    The WiMAX, also known as IEEE 802.16, provides a mechanism for deploying high-speed wireless mesh network, (an ubiquitous wireless network) in metropolitan areas.  WiMAX technology can be used as ``last mile ubiquitous" broadband connections to deliver streaming audio or video to clients. Thus, Quality of Service (QoS) is very important for WiMAX networks. Providing QoS in multi-hop WiMAX networks such as WiMAX mesh networks is challenging since the WiMAX mesh networks MAC is connectionless based and does not have proper support guarantees for QoS over multiple hops.  As a result, multiple links can interfere with each other when they are scheduled at the same time. The scheduling function plays a crucial role in QoS support, and various algorithms have been proposed and analyzed. These analysis basically assume a backlogged situation evenly in all queues.  However, multimedia traffic is bursty in nature, and the fairness of bursty traffic relative to continuous traffic has not been fully studied yet. Therefore, in this paper, we will discuss the potential unfairness that bursty traffic may be subjected to and propose a new frame-based packet scheduling algorithm. The scheduling is evaluated with multiple channels on WiMAX mesh nodes, which are operated in a distributed coordinated scheduling mode. Each wireless node has a single radio interface which is able to switch between multiple channels.  We evaluated the performance of the proposed dynamic changing scheduling method by extensive simulations, and it was shown to provide fair bandwidth allocation while increasing the traffic performance by means of throughput.

  • 329.
    Fragkiadakis, Alexandros
    et al.
    Fdn Research and Technology Hellas, Greece .
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Tragos, Elias Z.
    Fdn Research and Technology Hellas, Greece .
    Securing Cognitive Wireless Sensor Networks: A Survey2014In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, no 393248Article, review/survey (Refereed)
    Abstract [en]

    Wireless sensor networks (WSNs) have gained a lot of attention recently due to the potential they provide for developing a plethora of cost-efficient applications. Although research on WSNs has been performed for more than a decade, only recently has the explosion of their potential applicability been identified. However, due to the fact that the wireless spectrum becomes congested in the unlicensed bands, there is a need for a next generation of WSNs, utilizing the advantages of cognitive radio (CR) technology for identifying and accessing the free spectrum bands. Thus, the next generation of wireless sensor networks is the cognitive wireless sensor networks (CWSNs). For the successful adoption of CWSNs, they have to be trustworthy and secure. Although the concept of CWSNs is quite new, a lot of work in the area of security and privacy has been done until now, and this work attempts to present an overview of the most important works for securing the CWSNs. Moreover, a discussion regarding open research issues is also given in the end of this work.

  • 330.
    Franco, Antonio
    et al.
    Lund University, Sweden.
    Fitzgerald, Emma
    Lund University, Sweden.
    Landfeldt, Björn
    Lund University, Sweden.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    LUPMAC: A Cross-Layer MAC Technique to Improve the Age of Information Over Dense WLANs2016In: 2016 23RD INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS (ICT), IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    Age of Information (AoI) is a relatively new metric introduced to capture the freshness of a particular piece of information. While throughput and delay measurements are widely studied in the context of dense IEEE 802.11 Wireless LANs (WLANs), little is known in the literature about the AoI in this context. In this work we study the effects on the average AoI and its variance when a sensor node is immersed in a dense IEEE 802.11 WLAN. We also introduce a new cross layer MAC technique, called Latest UPdate MAC (LUPMAC), aimed at modifying the existing IEEE 802.11 in order to minimize the average AoI at the receiver end. This technique lets the MAC layer keep only the most up to date packets of a particular piece of information in the buffer. We show, through simulation, that this technique achieves significant advantages in the case of a congested dense IEEE 802.11 WLAN, and it is resilient to changes in the variance of the total network delay.

  • 331.
    Fransson, Anton
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Granqvist, Michael
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Improving the inventory control of spare parts at Nextjet AB2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nextjet anser att de har ett ofördelaktigt beställnings- och lagerhållningssystem av reservdelar, och mest problem är det med o-ringarna och skruvarna. Beställning sker oftast först när ett behov uppstår vilket ibland kan leda till att plan blir stående och därmed att potentiella intäkter uteblir. I denna studie har en lagerstyrningsstrategi framställts för o-ringarna och skruvarna i Nextjets reservdelslager. Under studiens gång genomfördes en artikelklassificering av o-ringarna och skruvarna på grund av att många av artiklarna hade en liknande karaktäristik. En lagerstyrningsmetod har sedan upprättats för vardera grupp som uppstått. De metoder som använts var beställningspunkt, återfyllnadsnivå och lot-for-lot. Resultatet av lagerstyrningsstrategierna har lett till att både kapitalbindningen och lagernivåerna har minskat i jämfört med nuläget samtidigt som risken för brist har minskat drastiskt. Lagernivåerna minskar med drygt 1000 artiklar och den maximala kapitalbindningen minskar med nästan 100 000 SEK i jämförelse med vad den är i nuläget.

  • 332.
    Fransson, Emelie
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Driving behavior modeling and evaluation of merging control strategies - A microscopic simulation study on Sirat Expressway2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Bangkok is a city where the congestion levels have been a major problem for many years. In 2017, Bangkok was rated the most congested city in Asia, and the second most congested in the world. According to The Expressway Authority of Thailand (EXAT), on-ramp merging is one of the most critical problem that causes congestion on the urban expressways. EXAT have evaluated several merging control strategies through microscopic traffic simulation to find suitable strategies for implementation in real life. However, their simulation studies were all based on the assumption that all motorists strictly follow the traffic rules. This is not the actual case in Bangkok, where the drivers ignore both solid lines and striped areas, as well as utilize the shoulder lane on a regular basis. The aim of this thesis is to investigate if it is possible to include this complex driving behavior in existing microscopic simulation models. A second objective is to identify merging control strategies that can reduce the occurrence and the effects of this driving behavior in order to increase the throughput at an on-ramp area on Sirat Expressway. A model was built in VISSIM and calibrated based on data collected from video recordings. In the study, parameters that are significant for the driving behavior modeling, as well as the difficulties that arise from performing a realistic calibration of the model using video observations and model-specific constraints, are identified. From the video recordings it was discovered that the main problem causing the congestion was a result of the mainline traffic who traversed to the on-ramp. Two merging control strategies were suggested to address this problem: the installment of a center barrier, and successive merging areas. The results confirmed that both actions can improve the traffic situation in terms of reducing the individual travel time. Installing a center barrier was the most efficient option and reduced the travel time by 16.58 % on the mainline and 63.24 % at the on-ramp.

  • 333.
    Franzén, Marcus
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Råsberg, Patrik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Internal charging of logistic services at OEM Automatic2015Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    OEM Automatic utför logistiktjänster åt enheter inom OEM-koncernen. För att debitera enheterna för de logistiktjänster som utförs används en kostnadsmodell. I dagsläget finns ett flertal problem med kostnadsmodellen som ger upphov till en missvisande debitering. I examensarbetet har därför en utredning gjorts för hur kostnadsmodellen kan utvecklas för att OEM Automatic ska kunna skapa en mer rättvisande debitering. Tre utvecklingsdelar för kostnadsmodellen har identifierats, vilka är debitering av fasta lagerhållningskostnader, en djupare kategorisering samt debitering av en fast orderkostnad. Implementering av de tre utvecklingsdelarna ger en ny kostnadsmodell med tre kostnadsposter och tre kostnadsdrivare där kostnader för att lagra och hantera artiklar synliggörs. Tänkbara effekter av en utvecklad kostnadsmodell är en ökad transparens och således mer rättvisande debitering av enheterna. Dessutom ger det upphov till att diskussioner kan föras mellan enheterna och OEM Automatic gällande hur lagerverksamheten bedrivs samt att beslut kan fattas på mer detaljerade grunder, vilket kan gynna hela koncernens resultat.

  • 334.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Janné, Mats
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Using computer based multi-actor multi-criteria evaluation methods in master logistics classes2018In: EurOMA 2018 Proceedings: To Serve, to Produce and to Servitize in the Era of Networks, Big Data, and Analytics, 2018Conference paper (Other academic)
    Abstract [en]

    The purpose is to provide insights into how to integrate a computer-based evaluation tool to improve the understanding of different perspectives when the teaching of logistics at masters’ level. This study has had an action research approach to student centred learning by introducing a theme of cross-functional decision making through combining lecturing, case assignment and computer based tools. What can be seen is that this inclusion has filled a gap in the education and course. Adding the combination of the preparatory case work and the computer exercise gave the students the activity independence and gave room for new reflections.

  • 335.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Jonsson, Patrik
    Chalmers Tekniska Högskola, Logistik och Transport.
    Consequences and Opportunities of a Global Two-Factory Production Network2014In: Global Operations Networks: Exploring new perspectives and agendas / [ed] Dmitrij Slepinov, Brian Vejrum Waehrens and John Johansen, Aalborg: Aalborg University Press , 2014, 1, p. 285-306Chapter in book (Other academic)
  • 336.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Jonsson, Patrik
    Chalmers Tekniska Högskola.
    The impact of knowledge properties on international manufacturing transfer performanceIn: Production planning & control (Print), ISSN 0953-7287, E-ISSN 1366-5871Article in journal (Refereed)
    Abstract [en]

    This paper examines how knowledge properties of a manufacturing activity transfer in international manufacturing network impact performance during the transfer itself and after steady state has been reached. With the aid of survey data from 178 companies, we use hierarchical regression to test the relationships. It is found that knowledge properties as a group significantly affect both performance measures when controlling for the effects of sender unit experience, sender unit size and receiver unit experience. The activities transferred thus impact the success of the transfer. The control variables of sender unit experience and receiver unit experience have their relatively strongest performance effects after steady state has been reached. Testing the performance effects of single knowledge property dimensions, we identify independency to have the strongest relative performance effect, which validates and advances previous research. This is one of the first survey studies to cover both the performance of the transfer itself and after reaching steady state of manufacturing transfers. Several strands of further research are therefore identified.  

  • 337.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Jonsson, Patrik
    Chalmers Univ Technol, Sweden.
    The impact of knowledge properties on international manufacturing transfer performance2019In: Production planning & control (Print), ISSN 0953-7287, E-ISSN 1366-5871, Vol. 30, no 2-3, p. 197-210Article in journal (Refereed)
    Abstract [en]

    This paper examines how knowledge properties of a manufacturing activity transfer in international manufacturing network impact performance during the transfer itself and after steady state has been reached. Hierarchical regression was used to test the relationship on survey data from 178 companies. Knowledge properties as a group was significantly affected by both performance measures when controlling for the effects of sender unit experience, sender unit size and receiver unit experience. The activities transferred thus impact the success of the transfer. The control variables of sender unit experience and receiver unit experience have their relatively strongest performance effects after steady state has been reached. Independency was the single knowledge property dimensions with the strongest relative performance effect. This is one of the first survey studies to cover both the performance of the transfer itself and after reaching steady state of manufacturing transfers. Several strands of further research were therefore identified.

  • 338.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Kjellsdotter Ivert, Linea
    Chalmers Tekniska Högskola, Gothenburg, Sweden.
    Hierarchical planning - an elusive good idea?2014Conference paper (Other academic)
  • 339.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Malm, Anna
    Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering. Saab Aeronautics, Linköping, Sweden.
    Johansen, Kerstin
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering.
    What are the differences between related offset and outsourcing?: A case study of a related offset business at Saab2016In: International Journal of Technology Transfer and Commercialisation, ISSN 1470-6075, E-ISSN 1741-5284, Vol. 14, no 2, p. 132-149Article in journal (Refereed)
    Abstract [en]

    Recently, offset contracts have become more complex. For the seller to carry through and review the effects and the demands of an offset contract, they need a framework.The paper identifies five main differences between outsourcing and related offset, which are translated into activities to be included in a suggested related offset framework. The paper is based on an in-depth case study of a related offset business at Saab, a Swedish military aircraft producer. The analysis compared the studied case with an existing outsourcing process identified in literature. The paper contributes by providing an overview of the activities taking place during a related offset process and showing the effect of the different hierarchical levels involved in the process on the efficiency of the fulfilment of the offset business. This paper is based on a single case study, and the suggested differences should be verified through further case studies.

  • 340.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Malm, Anna
    Saab AB Aeronautics, Linköping, Sweden.
    Skov Madsen, Erik
    SDU Centre for Sustainable Supply Chain Engineering, Institute of Technology and Innovation, Syddansk Universitet, Odense, Denmark.
    Technology transfer as apart of the business: Inter-organizational transfer strategies based on experiences of aircraft production2018In: Journal of Global Operations and Strategic Sourcing, ISSN 2398-5364Article in journal (Refereed)
    Abstract [en]

    Purpose

    The purpose of this paper is through a literature study and a study of the Saab offset cases to identify strategies to increase inter-organizational transfer capability.

    Design/Methodology/Approach

    Based on a literature study and a study of three of Saab’s offset cases and Saab’s process for technology transfer.

    Findings

    This study has identified inter-organisational transfer strategies based on the importance of the hierarchy of decision-making and the change from capacity transfers to capability transfers in offset business. 1) The type of performance goals set in the business agreement decides how to realise the transfer. 2) The hierarchy of decision-making create a need to align the understanding of the performance goals between the different parts of the organisation, which affect the plans for how to transfer knowledge between the organizational as well as the individual levels. 3) To reach the performance goals of the technology transfer there need to be a balance between the disseminative capability of the sender and the absorptive capability of the receiver.

    Limitations

    This study is based on a single case within a relatively unique industry with an offset perspective and production transfers. Therefore, there is also a need for future studies to confirm the identified relationships within outsourcing/offset within other industries and other types of transfers.

    Originality/value: A change from capacity transfers to capability transfers in both outsourcing/offshoring and offset business indicates that more research should be placed on the disseminative capacity of the sender. The literature review revealed that the disseminative capacity of the sender has been the subject of less research than the absorptive capacity of the receiver.

  • 341.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Medbo, Per
    Chalmers Tekniska Högskola.
    Johansson, Mats
    Chalmers Tekniska Högskola.
    Safety stock determination during production transfer2015In: Proceedings of EurOMA 2015, Neuchatel, Schweiz, 2015Conference paper (Refereed)
    Abstract [en]

    The purpose is to identify, through a simulation study, how the size of the extra safety stock needed when transferring production vary with uncertainties introduced by the transfer. The study shows that there is a substantial uncertainty increase during production transfer, related to the uncertainty of time to reach steady state. Learning curve factors have the largest impact, while the effects for the production yield factors are about of half their size, but still considerably large in relation to the regular safety stock. The study contributes by structuring the decision problem and indicating the importance of various uncertainties.

  • 342.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Thunberg, Micael
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Danielsson, Johan
    Arcona AB, Sweden.
    Hyll, Henrik
    NCC Construction.
    Sandberg, Erik
    Optimity AB.
    Westin, Arvid
    Arcona AB.
    Hur taktisk planering kan underlätta resursplanering i byggbranschen – Processer och IT-verktyg2017Conference paper (Other academic)
    Abstract [sv]

    Syftet med denna artikel är att visa på hur resurser inom byggföretag kan planeras på taktisk nivå med hjälp av optimeringsverktyg. Den rådande högkonjunkturen i Sverige med högre efterfrågan från beställare än vad byggentreprenörerna kan levererar måste entreprenörerna aktivt välja vilka projekt man ska gå in med anbud på. Beslutet måste vara välgrundat på information gällande efterfrågade projekt, tillgängliga resurser och potentiell vinstmarginal på projekten. Det är här taktisk planering kommer in genom att balansera potentiella projekt med den kapacitet byggföretaget har för att kunna gå in med anbud på de projekt som genererar högst vinstmarginal. Genom att studera två byggföretag (NCC och Arcona) presenteras processer och IT-verktyg för taktisk planering inom bygg. I NCC:s fall har fokus legat på att skapa sammanhållna processer och IT-verktyg för att hämta in data om framtida projekt och aktivt välja rätt projekt baserat på vilka reseurs dessa kräver, vilken kapacitet man har tillgängliga när projektet startar och vad vinstmarginalen blir. I Arconas fall har fokus legat på att skapa sammanhållna processer och IT-verktyg för att balanser aktiviteter och materialbehov genom hela byggprojektet.  På så sätt kan man i framtiden bättre planera behovet av kapacitet i deras nyutvecklade terminallösning baserat på hur mycket material som kan tänkas flöda genom den mht framtida projekt. Resultatet från studien visar på behovet av taktisk planering bland byggföretagen och hur den planeringen agerar som en länk mellan strategiska beslut och operativt arbete. Detta är ett viktigt bidrag för byggföretagen då de har beslutsstöd för att kunna fatta ett välgrundat beslut på vilka projekt man ska gå in med anbud på.

     

  • 343.
    Fredriksson, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Thunberg, Micael
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Shurrab, Hafez
    Department of Technology Management and Economics, Chalmers University of Technology.
    Torres, Joan
    Chalmers Industriteknik (CIT).
    Exploring contextual variables of tactical planning within the construction industry2017Conference paper (Refereed)
    Abstract [en]

    The purpose is to explore what context dependencies within the planning environment of the construction industry that need to be considered designing tactical planning processes. The preliminary result using a Delphi study including architects, clients, contractors, researchers, and suppliers indicates that the top five most important context dependencies are: Several kinds of stakeholders, Several planning phases, Lack of standardisation in planning, Low information sharing, and Opportunistic behaviour. Based on the patterns between the different expert groups two propositions are developed, indicating lack of shared understanding of planning between different stakeholders in construction and a project focus when thinking of planning.

  • 344.
    Fredriksson, Jonathan
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lindberg, Wilhelm
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Optimization model to improve the planning of a mobile abattoir2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today the planning of the transports at Hälsingestintan is done without any tools. Every year the problem regarding the planning is getting more complex and complicates the logistics of the transports. The purpose with the study is to investigate the logistics related to the mobile abattoir and the refrigerated truck in Hälsingestinans process flow. This is relevant due to identify if an optimization model has potential to reduce the transport costs when using this concept. Furthermore, the difference between the used planning strategies of the model and Hälsingestintan will be compared to identify if there are any clear differences between the methods.

  • 345.
    Fredriksson, Peter
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Tafreshi, Simon
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Recycling in the demolition industry - a case study of Destroy AB2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Landfill and mixed wastes are more expensive to dispose of than sorted wastes, and also decrease the possibilities for recycling of wastes. This thesis aimed towards determining what the potential benefits could be with leasing a sorting site and whether or not Destroy RC AB should introduce a sorting site to their business from a primarily economic perspective. The materials included in landfill and mixed wastes were determined and were prioritized differently depending on the economic and environmental benefit from sorting and recycling each material. If a sorting site was introduced to Destroy’s network of processes, unsorted waste types would be sent to the sorting site from demolition sites instead of to landfill and recycling sites. Scenarios with different variations of amounts of wastes at the sorting site, compositions of wastes, truck types used for transports, and sorting speeds were studied and used for total cost analyses

  • 346.
    Frick, Jesper
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Osman, Aweys Mohamed
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Homebuyers choices and valuations2015Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Det finns en generellt god kunskap inom byggnadsbranschen om vilka lägen och byggnadsformer som värderas högst hos bostadsköpare i Sverige. Byggnadsbranschen har dock inte lika bra kunskaper om vad som är att föredra inom bostaden i fråga eftersom dessa värderingar ändrar sig snabbt med tiden. Vilka värderingar har egentligen bostadsköpare när det kommer till bostadens konstruktion, funktionalitet och utformning? Svaret på denna fråga skulle gynna både företagen och bostadsköpare. Syftet med denna studie är just att besvara denna fråga med begränsning till flerbostadshus. Syftet är också att ta reda på hur konstruktionslösningar på en högre nivå än standard påverkar bostadsköparens vilja att betala mer för bostaden. Examensarbetet bygger på en förfrågan av Botrygg AB som vill veta mer om vad bostadsköpare har för värderingar och vilka val de gör om de kan påverka bostaden. För att uppfylla syftet har en kvantitativ studie genomförts där resultatet baseras på en enkätundersökning. Enkäten bestod av tydligt formulerade fleralternativs frågor där den svarande fick värdera olika påståenden och konstruktionslösningar. För att skapa enkäten har en djupare litteraturstudie genomförts. Enkäten visar en mängd intressanta resultat bland annat att bostadsköpare gärna har möjlighet att påverka sin framtida bostad, vare sig det handlar om innan de flyttat in eller efter. Bostadens utformning och planlösning är viktigare än bostadsytan och priset, där det även är tydligt att en öppen eller halvöppen planlösning är att föredra. Det viktigaste med bostadens kök är att det är utformat med fokus på arbetsyta och förvaring. Konstruktionslösningar med högre nivå än standard ökar generellt viljan att betala mer för bostaden, men eftersom svaren skiljer sig mycket handlar det mer om att hitta rätt köpare än en lösning som passar alla. De svarande uttrycker också att det som de är mest nöjda med i sin nuvarande bostad är att den är genomförd med hög konstruktionskvalitet.

  • 347.
    Frid, Olle
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Grehn, Jakob
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Key performance indicators for resilience when disturbance occur in the Swedish railway system2016Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Järnvägen drabbas av olika störningar vilket skapar förseningar i trafiken. Trafikverket och det branschgemensamma samarbetet ”Tillsammans för tåg i tid” (TTT) efterfrågar ett nyckeltal för resiliens. Nyckeltalet ska kunna användas för att mäta resiliens då tåg i det svenska järnvägssystemet drabbats av en störning. En störning är något som inträffar och minskar ett systems operativa förmåga. Mätning av resiliens och aktivt arbete för att öka resiliens kan användas till arbete för förbättrad punktlighet. Studien går ut på att ta fram detta nyckeltal och anpassa det för Trafikverket och TTT. I studien framkommer det att ett mått för resiliens visar hur väl ett system kan motstå störningar, anpassa sig under störning och hur väl systemet återställer sig efter störning. Resiliens består följaktligen av tre kategorier: motståndskraft, anpassningsförmåga och återställningsförmåga. Dessa tre kategorier är väsentliga för hur modellen för mätning av resiliens ska definieras. I studien framkommer det också att nyckeltalet resiliens är beroende av tidpunkter relaterade till störningshanteringen och indikatorn kapacitet. Kapaciteten för järnvägssystemet bestäms till kvoten av antal tåg i tid och totalt antal tåg. Den modell som utgås från är Francis and Bekera (2014) där resiliensen presenteras som en faktor av återställningsförmåga, anpassningsförmåga och motståndskraft. Resiliensen beräknas med hjälp av en modell där kapacitetsvärden för olika tidpunkter, då en störning inträffar, behövs. Utöver kapaciteten behövs även tidpunkterna för dessa kapacitetsvärden såväl som sannolikheten för att störningen upprepas. Dessutom behövs en parameter som bestämmer hur betydelsefullt det är att återställningen är snabb. Modellen ger ett resiliensvärde som ligger mellan 1 och 0, där 1 är det bästa värdet som betyder att systemet är fullt resilient mot just den störningen. Modellen är bäst tillämpad då en enskild störning inträffar på en begränsad sträcka istället för ett flertal störningar. Dock är modellen inte tänkt att användas då trafiken är helt stillastående utan när minst ett tåg kan nå sitt mål. Slutligen kan värdet för resiliens till exempel användas som ett jämförelsemått för olika sträckor vid ett beslutsunderlag för resursplanering.

  • 348.
    Friedrichs, Stephan
    et al.
    Max Planck Institute for Informatics, Germany /Saarbrucken Graduate School of Computer Science.
    Hemmer, Michael
    TU Braunschweig, IBR, Algorithms Group, Braunschweig, Germany.
    King, James
    D-Wave Systems, Burnaby, Canada.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The continuous 1.5D terrain guarding problem: Discretization, optimal solutions, and PTAS2016In: Journal of Computational Geometry, ISSN 1920-180X, E-ISSN 1920-180X, Vol. 7, no 1, p. 256-284Article in journal (Refereed)
    Abstract [en]

    In the NP-hard continuous 1.5D Terrain Guarding Problem (TGP) we are given an xx-monotone chain of line segments in R2 (the terrain TT), and ask for the minimum number of guards (located anywhere on TT) required to guard all of TT. We construct guard candidate and witness sets G,W⊂T of polynomial size such that any feasible (optimal) guard cover G∗⊆Gfor WW is also feasible (optimal) for the continuous TGP. This discretization allows us to: (1) settle NP-completeness for the continuous TGP; (2) provide a Polynomial Time Approximation Scheme (PTAS) for the continuous TGP using the PTAS for the discrete TGP by Gibson et al.; (3) formulate the continuous TGP as an Integer Linear Program (IP). Furthermore, we propose several filtering techniques reducing the size of our discretization, allowing us to devise an efficient IP-based algorithm that reliably provides optimal guard placements for terrains with up to 10^6 vertices within minutes on a standard desktop computer.

  • 349.
    Fryk, Pontus
    et al.
    Uppsala University, Sweden.
    Steins, Krisjanis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A modern process perspective, process mapping, and simulation in health care: Opportunities and IT infrastructural needs2010In: Proceedings of 2010 IEEE Workshop on Health Care Management (WHCM), 2010, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Today, health care organizations often claim that theyare “process oriented”, and that one should approach health carefrom a process perspective in order to utilize the present ITrelated benefits; such as increased service quality, cost efficiency,and enhanced communication. In this paper we investigate howwell founded the concept of process orientation really is – byexamining IT/IS infrastructures, and procedures for processdefinition, visualization, and evaluation – at a prominent hospitalin Stockholm, Sweden. A case study of the organization and theinteraction of the emergency and radiology departments at thesame hospital (using process mapping and data analysis) revealsdata fragmentation, incompatible data, and disparateinformation systems. This results in difficulties regarding processdefinition and analysis, which makes the use of innovative toolssuch as simulation, problematic. The implications of this, and thecontextual factors, are also discussed and some finalrecommendations for smooth digitization are put forth.Today, health care organizations often claim that theyare “process oriented”, and that one should approach health carefrom a process perspective in order to utilize the present ITrelated benefits; such as increased service quality, cost efficiency,and enhanced communication. In this paper we investigate howwell founded the concept of process orientation really is – byexamining IT/IS infrastructures, and procedures for processdefinition, visualization, and evaluation – at a prominent hospitalin Stockholm, Sweden. A case study of the organization and theinteraction of the emergency and radiology departments at thesame hospital (using process mapping and data analysis) revealsdata fragmentation, incompatible data, and disparateinformation systems. This results in difficulties regarding processdefinition and analysis, which makes the use of innovative toolssuch as simulation, problematic. The implications of this, and thecontextual factors, are also discussed and some finalrecommendations for smooth digitization are put forth.

  • 350.
    Furda, Daniel
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Bagherzadeh Saffarian, Bahareh
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Work Zone's Capacity Estimation and Investigation of Potential of Dynamic Merge Systems2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Work zones are an essential part of roads maintenance. Despite all the efforts addressed to reduce work zone’s negative impacts on the road traffic performance and improve the road safety, there still exist work zone related congestions and traffic problems. This thesis aims to study and analyze highway reconstruction/maintenance activities, their impacts and existing ways of reducing these negative effects and investigating the role of Intelligent Transport Systems in improvement of the difficulties caused by work zones. The research of the factors influencing capacity resulted in three factors presented in each considered study. The factors are heavy vehicle percentage, weather conditions and police presence. An unusual approach presented by Weng & Meng (2011) distinguishes among the examined analytical models. Their Decision-Tree model, based on training a large data set, showed significantly lower values of errors of prediction of level-of-service. Three different dynamic late merge systems (DLMS) have been simulated and analyzed using the AIMSUN micro-simulation software. The simulation outcome shows promising results favoring the use of DLMS. Among the simulated systems is extra focus put on the ALINEA algorithm that shows potential to improve traffic flow in work zones. Conducted sensitivity analysis shows different behaving of the ALINEA algorithm due to change of regulator parameter and critical occupancy. In order to investigate performance of the ALINEA algorithm, an extensive research has to be conducted. The research should include various work zone configurations as well as different values of heavy vehicle percentage and the parameters within the algorithms code should be subjects to optimization.

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