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  • 1.
    Aaboen, Lise
    et al.
    Department of Industrial Economics and Technology Management, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Fredriksson, Anna
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The relationship development aspect of production transfer2016In: Journal of Purchasing and Supply Management, ISSN 1478-4092, E-ISSN 1873-6505, Vol. 22, no 1, p. 53-65Article in journal (Refereed)
    Abstract [en]

    Production transfers are a result of outsourcing and offshoring decisions. Because of the strategic focus of the outsourcing literature, the operational issues of relationship development between sender and receiver and its impact on the transfer progress have not been fully depicted. The purpose of the present paper is to explore relationship development during production transfer. To fulfil this purpose, we studied three different production transfers and derived four propositions for further testing. Our main conclusions included that dependence and power gradually shift between the sender and the receiver and that the relationship between them sets the arena for what types of relationships can be developed between the receiver and the suppliers. Furthermore, short social distances can bridge cultural and technological distances to some extent, because it motivates the actors to bring their relationship into a more developed state. Finally, we noticed that the headquarters’ involvement can work both as an inhibitor as well as a converter.

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  • 2.
    Aban, Kevin
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Göst, Jens
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Analysis of transports with pharmaceuticals on Arlanda airport2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Rapporten syftar till att kartlägga och analysera dagens transportflöde av läkemedel på fraktområdet Cargo City på Arlanda. Cargo Center och APH Logistics är två fraktagenter som har sin verksamhet på Cargo City. Observera att Cargo City och Cargo Center inte har samma innebörd. Cargo Center och APH Logistics erbjuder genom nära samarbete transport och hantering av temperaturkänsligt gods, som till exempel läkemedel. Läkemedel är värdefullt gods som kräver särskild skötsel vid transport, hantering och förvaring. Det ställer stränga krav på samtliga aktörer i försörjningskedjan. Genom studiebesök och intervjuer har författarna kartlagt det befintliga flödet av läkemedel. SACT, ett åkeri och dotterbolag till Cargo Center, utför transporten av godset till Cargo City med nerkylda lastbilar. APH Logistics omlastningsterminal på Cargo City är temperaturkontrollerad, vilket innebär att läkemedelsgodset förvaras och lastats i flygcontainrar där. Det färdiglastade godset forslas sedan vidare till Cargo Centers terminal. Där sker vikt- och volymkontroll av godset, det registreras i olika datasystem och slutligen märks det med etiketter, så som flygfraktsedeln. Mycket av godset som hanteras på Arlanda körs med lastbil till andra flygplatser och destinationer runt om i Europa istället för att flygfraktas direkt från flygplatsen. Dessutom hanteras och förvaras inte allt läkemedelsgods under temperaturkontrollerade former. En totalkostnadsanalys har gjorts för att jämföra olika transportflödesscenarion. Dessutom har författarna identifierat den kundservice Cargo Center och APH Logistics bör erbjuda kunden. Den bygger på kvalitativa resonemang. Resultatet av rapporten är författarnas rekommendation till företagen av hur de bör gå tillväga i framtiden. Den ger både kortsiktiga och långsiktiga tips.

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  • 3.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A Reinforcement Learning Framework for Optimizing Age of Information in RF-Powered Communication Systems2020In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 68, no 8, p. 4747-4760Article in journal (Refereed)
    Abstract [en]

    In this paper, we study a real-time monitoring system in which multiple source nodes are responsible for sending update packets to a common destination node in order to maintain the freshness of information at the destination. Since it may not always be feasible to replace or recharge batteries in all source nodes, we consider that the nodes are powered through wireless energy transfer (WET) by the destination. For this system setup, we investigate the optimal online sampling policy (referred to as the age-optimal policy) that jointly optimizes WET and scheduling of update packet transmissions with the objective of minimizing the long-term average weighted sum of Age of Information (AoI) values for different physical processes (observed by the source nodes) at the destination node, referred to as the sum-AoI. To solve this optimization problem, we first model this setup as an average cost Markov decision process (MDP) with finite state and action spaces. Due to the extreme curse of dimensionality in the state space of the formulated MDP, classical reinforcement learning algorithms are no longer applicable to our problem even for reasonable-scale settings. Motivated by this, we propose a deep reinforcement learning (DRL) algorithm that can learn the age-optimal policy in a computationally-efficient manner. We further characterize the structural properties of the age-optimal policy analytically, and demonstrate that it has a threshold-based structure with respect to the AoI values for different processes. We extend our analysis to characterize the structural properties of the policy that maximizes average throughput for our system setup, referred to as the throughput-optimal policy. Afterwards, we analytically demonstrate that the structures of the age-optimal and throughput-optimal policies are different. We also numerically demonstrate these structures as well as the impact of system design parameters on the optimal achievable average weighted sum-AoI.

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  • 4.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    AoI-Optimal Joint Sampling and Updating for Wireless Powered Communication Systems2020In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 69, no 11, p. 14110-14115Article in journal (Refereed)
    Abstract [en]

    This paper characterizes the structure of the Age of Information (AoI)-optimal policy in wireless powered communication systems while accounting for the time and energy costs of generating status updates at the source nodes. In particular, for a single source-destination pair in which a radio frequency (RF)-powered source sends status updates about some physical process to a destination node, we minimize the long-term average AoI at the destination node. The problem is modeled as an average cost Markov Decision Process (MDP) in which, the generation times of status updates at the source, the transmissions of status updates from the source to the destination, and the wireless energy transfer (WET) are jointly optimized. After proving the monotonicity property of the value function associated with the MDP, we analytically demonstrate that the AoI-optimal policy has a threshold-based structure w.r.t. the state variables. Our numerical results verify the analytical findings and reveal the impact of state variables on the structure of the AoI-optimal policy. Our results also demonstrate the impact of system design parameters on the optimal achievable average AoI as well as the superiority of our proposed joint sampling and updating policy w.r.t. the generate-at-will policy.

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  • 5.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Online Age-minimal Sampling Policy for RF-powered IoT Networks2019In: 2019 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    In this paper, we study a real-time Internet of Things (IoT)-enabled monitoring system in which a source node (e.g., IoT device or an aggregator located near a group of IoT devices) is responsible for maintaining the freshness of information status at a destination node by sending update packets. Since it may not always be feasible to replace or recharge batteries in all IoT devices, we consider that the source node is powered by wireless energy transfer (WET) by the destination. For this system setup, we investigate the optimal online sampling policy that minimizes the long-term average Age-of-Information (AoI), referred to as the age-optimal policy. The age-optimal policy determines whether each slot should be allocated for WET or update packet transmission while considering the dynamics of battery level, AoI, and channel state information (CSI). To solve this optimization problem, we model this setup as an average cost Markov Decision Process (MDP). After analytically establishing the monotonicity property of the value function associated with the MDP, the age-optimal policy is proven to be a threshold based policy with respect to each of the system state variables. We extend our analysis to characterize the structural properties of the policy that maximizes average throughput for our system setup, referred to as the throughput-optimal policy. Afterwards, we analytically demonstrate that the structures of the age optimal and throughput-optimal policies are different. We also numerically demonstrate these structures as well as the impact of system design parameters on the optimal achievable average AoI.

  • 6.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Dhillon, Arpreet S.
    Virginia Tech, VA 24061 USA.
    On the Role of Age of Information in the Internet of Things2019In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 57, no 12, p. 72-77Article in journal (Refereed)
    Abstract [en]

    In this article, we provide an accessible introduction to the emerging idea of Age of Information (AoI) that quantifies freshness of information and explore its possible role in the efficient design of freshness-aware Internet of Things (IoT). We start by summarizing the concept of AoI and its variants with emphasis on the differences between AoI and other well-known performance metrics in the literature, such as throughput and delay. Building on this, we explore freshness-aware IoT design for a network in which IoT devices sense potentially different physical processes and are supposed to frequently update the status of these processes at a destination node (e.g., a cellular base station). Inspired by recent interest, we also assume that these IoT devices are powered by wireless energy transfer by the destination node. For this setting, we investigate the optimal sampling policy that jointly optimizes wireless energy transfer and scheduling of update packet transmissions from IoT devices with the goal of minimizing long-term weighted sum-AoI. Using this, we characterize the achievable AoI region. We also compare this AoI-optimal policy with the one that maximizes average throughput (throughput-optimal policy), and demonstrate the impact of system state on their structures. Several promising directions for future research are also presented.

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  • 7.
    Abdul Aziz Hasan Ali, Aamir
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Shahzad, Muhammad Adil
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A Joint Subcarrier/Power allocation Scheme for OFDMA-based Cellular Networks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The assignment of this master thesis consists of initiating power, subcarrier allocation in a dynamic FFR based scheme designed for multi-cell OFDMA networks and to enhance the throughput of all center users in bandwidth hungry borrower cells (overloaded cells) which was previously degraded by original FFR3 scheme as a result of partitioning of system bandwidth into center and edge bands respectively. The method uses band borrowing to compensate center user’s throughput loss in a semi and fully overloaded system. The scheme uses dynamic programming method (0/1 knapsack problem) to bargain an edge band on various power levels and tends to check the best combination (power and sub-carrier) which the system can utilize while still maintaining acceptable throughput loss for the users at the edge of the neighboring cell (lender cell).

    The algorithm consists of generating a borrowing request to neighboring cells for utilizing their edge bands by the overloaded borrower cell if their average center user throughput reaches below a minimum threshold value set in the system. The borrowing method uses 0/1 knapsack problem to capture an edge band based on limiting factors of total cost in average throughput losses by neighbors (Ci) and Un (tolerable mean user edge user throughput loss by lending cell). While solving knapsack problem the lender (neighbors) will check Ci and Un before granting the right to use its edge band. The later stage requires reducing subcarrier power level in order to utilize the lenders edge band using "soft borrower" mode. The borrowed sub-carriers will be activated take power from the original center band sub-carriers of the overloaded cell by taking into account the interference between the lender and the borrower. In case of negative (0) reply from the lender cell after the first request, multiple requests are generated at reduce power level at every step to order to acquire more bands. If a neighbor has band borrowing requests from multiple overloaded base stations, the band will be granted to the one which gives minimal loss in terms of throughput to the lender cell.

    The simulation results are analyzed w.r.t reuse-1 and FFR3 scheme of a multi cell regular and irregular scenarios comprising of lightly to heavily overloaded cells with various subcarrier allocation patterns. An overhead and time assessment is also presented between borrower and lender cells. Simulation results show an increase of 60% in center user’s throughput w.r.t original FFR3 scheme with an acceptable loss of 18% at the edges in complex overloaded scenarios while the overall system throughout increases by 35%.

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  • 8.
    Abrahamsson, Kalle
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Åtgärd för ökad trafiksäkerhet - Undersökning om behovet av nya säkra övergångar vid Riksväg 51 i Finspång2020Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Fordonstrafiken ökar allt mer i Sverige, antalet lastbilstransporter likaså riksväg 51 står inför nybyggnation som ska öka framkomligheten för fordon genom Finspång, men vem tänker på gång och cykeltrafikanterna? Denna rapport undersöker framkomligheten för en problematisk sträcka av Riksväg 51 genom Finspång, där hastighetsbegränsningen är hög och bristen på säkra övergångar är stor. Passageräkning kommer utföras vid två områden för att få svar på hur stort problemet är för Finspångs invånare. Rapporten resulterar i förslag till två nya säkra övergångar, en gångbro vid Postnords kontor i Finspång och en tunnel intill en cirkulationsplats i anslutning till Willys i Finspång. Om kommunen anser att dessa förslag är något att arbeta vidare med är helt upp till dem.

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  • 9.
    Abrishami, Mahdi
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Dynamic Link Flow Estimation according to Historical Travel Times2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vast application of ITS and the availability of numerous on-road detection devices has resulted in variety of alternative data sources to be exploited and used in the field of traffic modelling. In this thesis, historical travel times, as an alternative data source, is employed on the developed method to perform dynamic network loading. The developed method, referred to as DNLTT, uses the share of each route available in the route choice set from the initial demand, as well as link travel times to perform the network loading. The output of the algorithm is time-dependent link flows. DNLTT is applied on Stockholm transportation network, where it is expected to have variation in link travel times in different time-periods, due to network congestion. In order to calculate the route shares, a time-sliced OD matrix is used. The historical travel times and the routes in the route choice set are extracted from an existing route planning tool. An available logit model, which considers the route travel time as the only logit parameter, is used for the route share calculation and the network loading is performed according to 2 different methods of DNLTT and DL. The evaluation of results is done for a toy network, where there happen different network states in different time-periods. Furthermore, the model output from Stockholm case study is analyzed and evaluated. The dynamic behavior of DNLTT is studied by analysis of link flows in different time-periods. Furthermore, the resulting link flows from both network loading methods are compared against observed link flows from radar sensors and the statistical analysis of link flows is performed accordingly. DNLTT exhibits a better performance on the toy network compared to DL, where the increasing link travel times cause the link flows to decline in different time-periods. However, the output of the developed method does not resemble the observed link flows for the investigated links in Stockholm case study. It is strongly believed, that the performance of DNLTT on the investigated transportation network potentially improves, in case the historical travel times better resemble the network dynamics. In addition to a more reliable data set, an OD adjustment process in all the time-periods is believed to generate better model output.

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    Dynamic Link Flow Estimation according to Historical Travel Times
  • 10.
    Adedokun, Adeyemi
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Application of Road Infrastructure Safety Assessment Methods at Intersections2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Traffic safety at intersections is a particularly difficult phenomenon to study, given the fact that accidents occur randomly in time and space thereby making short-term measurement, assessment and comparison difficult. The EU directive 2008/96/EC introduced road infrastructure safety management, which offers a five layer structure for developing safer road infrastructure has been used to develop tools for accident prediction and black spot management analysis which has been applied in this work to assess the safety level of intersections in Norrköping city in Sweden. Accident data history from STRADA (Swedish Traffic Accident Data Acquisition) and the network demand model for Norrköping city were used to model black spots and predict the expected number of accidents at intersections using PTV Visum Safety tool, after STRADA accident classification was restructured and the Swedish accident prediction model (APM) was configured and tested to work within the tool using the model from the Swedish road administration (SRA). The performance of the default (Swiss) and the Swedish APM was compared and identified locations with the high accident records, predicted accident counts and traffic volumes were audited using qualitative assessment checklist from Street-Audit tool. The results from these methods were analysed, validated and compared. This work provides recommendations on the used quantitative and qualitative methods to prevent accident occurrence at the identified locations.

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  • 11.
    Adelsköld, Astrid
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Review of general demand responsive transport in Sörmland county2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sörmlands län består till stor del av landsbygd där en kostnadseffektiv kollektivtrafik är svår att uppnå eftersom resandeunderlaget och därmed även efterfrågan normalt är låg. I dessa områden finns dock potential att uppnå en hållbar kollektivtrafik med hjälp av anropsstyrda trafikformer. I detta projekt utreddes dels en övergång av turer i landsbygdslinjetrafiken till allmän anropsstyrd trafik och dels en samordning av den allmänna och särskilda anropsstyrda kollektivtrafiken. En generell metod för val mellan fast linjetrafik och anropsstyrd linjelagd trafik utvecklades, vilken bestod av enkla tumregler för utvärdering av turer med regelbundet låg efterfrågan i landsbygdslinjetrafiken. Samordningen bestod av att utreda effekterna av att kompletteringsresor planerades och utfördes med samma fordon som den särskilda anropsstyrda kollektivtrafiken. Då kompletteringstrafiken får en högre kostnadseffektivitet genom samordning med den särskilda kollektivtrafiken kan denna användas som en flexibel ersättning där turutbudet i landsbygdslinjetrafiken behöver minska. En kostnadseffektivisering av landsbygdslinjetrafiken där turutbudet anpassas bättre till efterfrågan tillåter därmed en satsning av resurser till kompletteringstrafiken. Detta för att i enlighet med kollektivtrafikmyndighetens mål skapa en attraktiv kollektivtrafik för hållbar tillväxt och utveckling i Sörmlands län.

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  • 12.
    Adelswärd, Viveka
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Davies, Norman F
    På väg mot ett nytt språk: Rapport från ASLA:s höstsymposium, Linköping, 9-10 november 19891990Conference proceedings (editor) (Other academic)
    Abstract [sv]

    1989 års ASLA symposium i Linköping valde ett tema som understryker utvecklingsaspekterna vid andra- eller främmandespråksinlärning. Nya rön om modersmålsutveckling är emellertid väsentliga eftersom många forskningsresultat pekar på stora likheter i språktillägnandeprocessen oavsett om det är fråga om ett första, andra eller främmande språk. Insikter från språkpsykologi, undervisningsteori och utvecklingsforskning har vidare stor betydelse för synen på hur undervisningsprocessen och klassrumsmetodiken skall förnyas.

    Denna volym inleds liksom symposiet av Åke Vibergs fylliga översikt över den senaste tidens forskning om språkinlärningsprocessen och dess eventuella följder för språkundervisningen.

    Olika aspekter av inlärarspråket kartläggs av Inge Bartning, som har undersökt svenska universitetsstuderandes utveckling i franska och av Björn Hammarberg, som har intresserat sig för inlärarens uttalslösningar inför ett delvis nytt ljudsystem. Suzanne Schlyters bidrag jämför de två språken hos naturligt tvåspråkiga barn för att försöka fastställa om det svagare språket mest liknar ett första språk (Ll) eller ett andra språk (L2).

    De flesta bidragen är tillägnade olika aspekter av undervisningsprocessen. Denna sektion inleds av Gunnar Tingbjörns granskning och jämförelse av hur språkämnena behandlas i grundskolans läroplan.

    Fyra bidrag presenterar delvis nya program för att uppfylla läroplanens krav. Elsie Wijk-Andersson har reviderat den vanliga sekvenseringen i metoder och material i svenskundervisning för gäststuderande, Eie Ericsson och Dieter Krohn lägger fram ett didaktiskt forskningsprojekt i skolans tyskundervisning, Lisa washburn beskriver ett försök till ’språkbadsprogram’ i engelska i ett svenskt gymnasium medan Rigmor Eriksson exemplifierar det växande intresset i Sverige för ’learner autonomy’, dvs elevstyrd undervisning.

    Sektionen avslutas med två artiklar som behandlar enskilda aspekter av undervisningsprocessen. Karin Aijmer jämför naturlig, talad engelska med läroboksdialoger och konstaterar att talspråksforskningen än så länge har lämnat få spår i skolböckerna. Christian Hecht och Maria Kroes-Hecht lägger fram preliminära resultat av ett projekt som söker att utnyttja konsekventa likheter mellan tyska och svenska ord i ordförståelseträning.

    Slutligen lyfter Jacob Mey fram en viktig aspekt av språkplaneringen, nämligen språket som maktmedel. Den kontroversiella frågan om vems språk vi egentligen lär ut borde stimulera till diskussion.

    Redaktörerna vill uttrycka sin tacksamhet till bokens alla författare som har bidragit till att ett livligt och lyckat symposium även har resulterat i en värdefull samlingsvolym. Vi vill också tacka Stiftelsen Tornbylyckorna – Lektorshagen i Linköping för finansiellt stöd till tryckningen av denna symposierapport.

     

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  • 13.
    Adelswärd, Viveka
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Sachs, L.
    Sachs, L..
    The messenger's dilemmas - Giving and getting information in genealogical mapping for hereditary cancer2003In: Health, Risk and Society, ISSN 1369-8575, E-ISSN 1469-8331, Vol. 5, no 2, p. 125-138Article in journal (Refereed)
    Abstract [en]

    Recent advances in genetic research can provide constructive preventive possibilities for individuals and society but also provide physicians and laypersons with new problems. For instance, in consultations dealing with the risk of getting hereditary cancer, physicians have to balance between the role of clinician, attending to the needs of a certain individual, and the role of researcher, collecting vital data for important research. Individuals taking part in these consultations not only have to interpret the information provided by the physicians. They might also be faced with the problem of informing others, often close kin, in a similar risk situation, or on the physician's behalf obtain information from them. They do not only receive bad news about themselves but are placed in a messenger's dilemma. The study is based on discourse data from 31 audio-taped talks between a physician and a person seeking information. Analyses of the consultations reveal how individuals seeking information about possible future diseases find themselves in a position where not only informing unknowing relatives, but also obtaining information from them, is experienced as giving them bad news.

  • 14.
    Adjiashvili, David
    et al.
    ETH, Switzerland.
    Bosio, Sandro
    ETH, Switzerland.
    Li, Yuan
    Lund University, Sweden.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Exact and Approximation Algorithms for Optimal Equipment Selection in Deploying In-Building Distributed Antenna Systems2015In: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 14, no 4, p. 702-713Article in journal (Refereed)
    Abstract [en]

    We consider a combinatorial optimization problemin passive In-Building Distributed Antenna Systems (IB-DAS) deployment for indoor mobile broadband service. These systems have a tree topology, in which a central base station is connected to a number of antennas located at tree leaves via cables represented by the tree edges. Each inner node corresponds to a power equipment, of which the available types differ in the number of output ports and/or by power gain at the ports. This paper focuses on the equipment selection problemthat amounts to, for a given passive DAS tree topology, selecting a power equipment type for each inner node and assigning the outgoing edges of the node to the equipment ports. The performance metric is the power deviation at the antennas from the target values. We consider as objective function the minimization of either the total or the largest power deviation over all antennas. Our contributions are the development of exact pseudo-polynomial time algorithms and (additive) fully-polynomial time approximation schemes for both objectives. Numerical results are provided to illustrate the algorithms. We also extend some results to account for equipment cost.

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  • 15.
    Adolfsson, Lovisa
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Nilsson, Rebecca
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Collection structure design of deposited PET bottles and aluminium cans in northern Sweden2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Returpack är ansvariga för Sveriges retursystem av tomma PET-flaskor och aluminiumburkar där insamling och hantering av förpackningar är en stor del av verksamheten. Transport av tomma förpackningar från butik till Returpacks fabrik i Norrköping sker huvudsakligen i form av lösvikt (bulklast) av Returpack. Övriga transporter av förpackningar sker i kartong eller säck där dryckesleverantörer sköter insamlingen. Syftet med denna studie är att skapa och undersöka olika typer av inhämtningsstrukturer för tomma förpackningar, där Returpack strävar efter att på ett kostnadseffektivt och miljömässigt sätt sköta inhämtningen samt öka kontrollen över flödet. I studien kommer fem områden i norra Sverige att undersökas, vilka skiljer sig från övriga områden i Sverige då dessa kännetecknas av långa avstånd mellan butiker samt låga volymer av förpackningar. I studien utförs ruttplanering av lösviktsinsamling samt totalkostnadberäkningar för varje område, där ett antal scenarier skapats med olika typer av inhämtningsstrukturer. I scenarierna varieras antalet butiker, mellanlager, ruttider samt insamlingsbilar. Utöver detta undersöks även fyra olika hubblösningar där förpackningarna gör en övergång från kartong- och säckflödet till lösviktsflödet. Resultaten av ruttplanerningarna visar att två av områdena har en hög belastning där antalet insamlingsbilar behöver ökas. Totalkostnadsberäkningarna tyder på att det går att sänka totalkostnaden i två av områdena genom att öka lösviktsinsamlingen. I de övriga tre områdena ger den nuvarande strukturen den lägsta totalkostnaden. Resultaten visar också att antalet fordonskilometer kan minska genom att addera ytterligare ett mellanlager i två av områdena. I studien visas det också att hubbar kan sänka kostnader för Returpack och minska antalet inkommande kartonger och säckar till fabriken. Att införa hubbar minskar också antalet fordonskilometer med mer än 50 %.

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    Collection structure design of deposited PET bottles and aluminium cans in northern Sweden
  • 16.
    Ahani, Ghafour
    et al.
    Komar University of Science and Technology, Iraq.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ding, Wei
    Ranplan Wireless Network Design Ltd, England.
    On SC-FDMA Resource Allocation with Power Control2016In: 2016 IEEE 21ST INTERNATIONAL WORKSHOP ON COMPUTER AIDED MODELLING AND DESIGN OF COMMUNICATION LINKS AND NETWORKS (CAMAD), IEEE , 2016, p. 112-116Conference paper (Refereed)
    Abstract [en]

    In this paper, single-carrier frequency division multiple accesses (SC-FDMA) is discussed. In particular, minimum stun power, subject to meeting users demand is considered. There are two channel allocation schemes, localized and interleaved. In localized scheme, a block of convective channels in the spectrum is allocated to each user. In interleaved scheme, channels will be spread out over the spectrum and will be distributed equidistantly. It has been previously assumed that when a block of channels is assigned to a user, the same amount of power will be allocated to each channel. However, the power could be used more efficiently without this assumption We show that the resulting power allocation problem can be solved in linear time and propose an optimal power allocation procedure. Next, the effect of this new power optimization procedure is investigated numerically. In the next part of paper, we prove that for the interleaved scheme, Minimum sum power problem with or without this new power optimization is polynomial solvable. Finally, we numerically compare localized and interleaved SC-FDMA with and without power optimization The results show that the localized scheme with the new power optimization yields the best performance

  • 17.
    Ahlberg, John
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Cruz Wolter Håkansson, Christoffer
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Identification, mapping and control of non-structure-bound materials2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    I Saab Aerostructures tillverkning av flygplansdelar, används icke strukturbundet material, det vill säga material som inte har en angiven kvantifierad förbrukning per tillverkad enhet eller material vars angivna kvantifierade förbrukning per tillverkad enhet inte stämmer överens med verklig förbrukning. Personal på inköpsavdelningen vet i vissa fall inte var ett specifikt icke strukturbundet material förbrukas, alltså vilka tillverkningsavdelningar eller flygplansdelar som förbrukar materialet. Likaså saknas övergripande och gemensamma rutiner för hur material som klassas som icke strukturbundet material planeras och lagerstyrs. För att identifiera problemområden i materialförsörjningen genomfördes en flödeskartläggning för att identifiera vilka olika typer av icke strukturbundet material som används i Saab Aerostructures produktion samt hur dessa lagerstyrs mellan lager och buffertlager i produktion. Under flödeskartläggningen definierades sex olika materialgrupper tillhörande icke strukturbundet material. För att lagerstyra de identifierade materialgrupperna av icke strukturbundet material används idag åtta stycken lagerstyrningsmetoder. Saab Aerostructures har anlitat tredjepartslogistiker för att sköta merparten av dagens lagerstyrning. Lagerstyrningsmetoderna skiljer sig åt beroende på tredjepartslogistiker och materialgrupp av icke strukturbundet material. Resultatet från genomförd kartläggning och analys påvisar att det finns förbättringspotential i flera utav dessa lagerstyrningsmetoder, samt att det är möjligt att reducera antalet lagerstyrningsmetoder genom att använda samma lagerstyrningsmetod för snarlika materialgrupper av icke strukturbundet material. Genomförd analys påvisar även behovet av ett förbättrat informationsflöde mellan beredning, inköp och produktion, när det gäller hanteringen av icke strukturbundet material. Konkreta åtgärder i form av rekommendationer, för att förbättra lagerstyrningen av icke strukturbundet material, presenteras i slutet av denna rapport.  

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    fulltext
  • 18.
    Ahlgren-Moritz, Charlotte
    et al.
    Malmö högskola, Sweden.
    Alm, Anna-Karin
    Malmö högskola, Sweden.
    Christersson, Cecilia
    Malmö högskola, Sweden.
    Eikelboom Sällström, Anette
    Enheten för externa relationer, Umeå universitet, Sweden.
    Esbjörnsson, Mattias
    Malmö högskola, Sweden.
    Jacobsson, Andreas
    Fakulteten för teknik och samhälle, Malmö högskola, Sweden.
    Marell, Agneta
    Samverkan och innovation, Umeå universitet, Sweden.
    Persson, Jeanette
    Innovation och utveckling, Malmö högskola, Sweden.
    Ramsten, Anna-Carin
    Linköping University, REMESO - Institute for Research on Migration, Ethnicity and Society. Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Rehme, Jakob
    Linköping University, Department of Management and Engineering, Industrial Economics. Linköping University, Faculty of Science & Engineering.
    Reinhold, Mats
    Enheten för externa relationer, Umeå universitet, Sweden.
    Sjögren, Karin
    Malmö högskola, Sweden.
    Sörensson, Victoria
    Enheten för externa relationer, Umeå universitet, Sweden.
    Värbrand, Peter
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Vägen till samverkanssäkrad utbildning. [1]: Metoder och strategier2016Book (Other academic)
    Abstract [sv]

    Universitet och högskolor bidrar till samhällsutvecklingen genom att forskningsbaserad kunskap tillämpas av olika aktörer i samhället. För att möta dagens och morgondagens samhällsutmaningar utgör således kunskapsutbyte och samverkan mellan lärosäten och samhället en värdefull möjlighet. Att ha starka relationer med samhällets aktörer identifieras också som viktigt i utvecklingen av ett internationellt starkt lärosäte.

    Samverkan i högre utbildning främjar samhällets förändringsförmåga och stärker utbildningens kvalitet, men samverkan förbereder också studenterna för ett livslångt lärande och underlättar övergången mellan utbildning och arbetsliv. Ett lärosäte i nära samverkan med aktörer i samhället är ett relevant lärosäte, det vill säga ett lärosäte som är till nytta för sin omvärld och för sina medarbetare och studenter.

    Ett grundläggande problem vad gäller möjligheterna att integrera samverkan i akademisk utbildning står att finna i statens fördelning av medel till lärosätena. De statliga medlen utgår nämligen i två separata anslag, ett vardera för de båda huvuduppdragen utbildning och forskning. Samverkan kan sägas ingå i bägge uppdragen. Till skillnad från forskningssamverkan finns det för utbildningssamverkan ingen särskild uppföljning och inte heller några ekonomiska incitament. Utvärdering av forskning och utbildning bör således breddas så att kvalitetsstärkande samverkansinslag också inkluderas i resursfördelningsprinciperna. Statens bristande strukturer för fördelning och uppföljning återspeglas i hur lärosätena fördelar resurser till och följer upp samverkan: lärare ges sällan resurser (i form av särskild tid) för att på ett pedagogiskt genomtänkt sätt kunna inkludera samverkansinslag i undervisningen; samverkan är sällan meriterande eller lönegrundande; och den utbildningssamverkan som bedrivs följs sällan upp – varken på institutions-, fakultets- eller lärosätesnivå. Samma sak kan sägas gälla på nationell nivå – det samverkande lärosätet erhåller inga extra anslag och det bestraffas ej heller för försummelse av detsamma. Att göra samverkan till en integrerad del av utbildningen innebär att samverkan bör ingå i de pedagogiska modeller som lärare använder för att leda studenternas kunskapsutveckling mot de mål som finns angivna i kurs- och utbildningsplaner. Det betyder också att arbetet med samverkan bör inkluderas i processer för styrning, planering och uppföljning av utbildning och undervisning på såväl kurs- och programnivå som på institutions-, fakultets- och lärosätesnivå. Att göra samverkan till en integrerad del av utbildningen är att sträva mot att externa aktörer ska bli en självklar del i den dagliga verksamheten – för studenter såväl som för medarbetare och för de organisationer man samverkar med. För att svenska lärosäten ska ges en realistisk möjlighet att göra samverkan till en integrerad del av utbildningsverksamheten krävs det framför allt följande:

    • att politiker och departement utformar ett fördelningssystem där framgångsrika samverkansinsatser inom utbildningen leder till en förstärkning av resursbasen på lärosätena;
    • att lärosätesledningar tar tydlig ställning för samverkansfrågan i sina strategiska styrdokument och att samverkan införs i lärosätenas kvalitetssäkringssystem för utbildning, samt att lärosätena inför system för att styra och följa upp samverkan i utbildningen på lärosätesövergripande nivå;
    • att ledningen för fakulteter, institutioner eller motsvarande omsätter lärosätets strategiska åtaganden i handlingsplaner och lokala styrdokument samt utformar system för dokumentation, styrning och uppföljning av samverkan i utbildningsprogram;
    • att lärare samt kurs- och programansvariga inför samverkan i utbildningens styrande dokument (t.ex. kurs- och utbildningsplaner) samt i den ordinarie undervisningsverksamheten.

    Dessutom bör lärosätena – både gemensamt men också vart och ett för sig – införa system och karriärvägar där medarbetares insatser i det vardagliga samverkansarbetet uppmärksammas och belönas.

    Mot bakgrund av detta kan man konstatera att det är angeläget att lärosätenas strategiska arbete avseende utveckling och uppföljning av samverkan i utbildningen vidareutvecklas. Men, med vilka verktyg, var i verksamheten och på vilka sätt?

    I följande skrift samlas erfarenheter och goda exempel gjorda inom ramen för ett flerårigt lärosätesövergripande samarbetsprojekt, Samverkanssäkrade utbildningsprogram, där utgångspunkten har varit att identifiera strategier och metoder för att integrera samverkan i utbildningsprogram. Målet har varit att undersöka och beskriva hur samverkan kan vara ett medel som bidrar till att stärka utbildningens kvalitet och relevans, samt ge förslag på hur vägen till samverkanssäkrad utbildning kan se ut.

    Den centrala slutsatsen är att samverkan, när den är en integrerad del av utbildningen, bidrar till kvalitet och säkerställer att utbildningen blir till nytta för samhället. Det finns också andra vinster med att bedriva ett systematiskt samverkansarbete, till exempel att det leder till pedagogisk utveckling för undervisande personal, att det ökar förutsättningarna för ett utmaningsbaserat lärande med studenten i centrum, att det underlättar övergången från studier till arbetsliv, och att det möjliggör fördjupade relationer med den värld lärosätet finns i. Resan mot samverkanssäkrad utbildning är, med andra ord, mödan väl värd.

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    Vägen till samverkanssäkrad utbildning. [1]: Metoder och strategier
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  • 19.
    Ahlgren-Moritz, Charlotte
    et al.
    Malmö högskola, Sweden.
    Alm, Anna-Karin
    Malmö högskola, Sweden.
    Christersson, Cecilia
    Malmö högskola, Sweden.
    Eikelboom Sällström, Anette
    Enheten för externa relationer, Umeå universitet, Sweden.
    Esbjörnsson, Mattias
    Malmö högskola, Sweden.
    Jacobsson, Andreas
    Fakulteten för teknik och samhälle, Malmö högskola, Sweden.
    Marell, Agneta
    Samverkan och innovation, Umeå universitet, Sweden.
    Persson, Jeanette
    Innovation och utveckling, Malmö högskola, Sweden.
    Ramsten, Anna-Carin
    Linköping University, REMESO - Institute for Research on Migration, Ethnicity and Society. Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Rehme, Jakob
    Linköping University, Department of Management and Engineering, Industrial Economics. Linköping University, Faculty of Science & Engineering.
    Reinhold, Mats
    Enheten för externa relationer, Umeå universitet, Sweden.
    Sjögren, Karin
    Malmö högskola, Sweden.
    Sörensson, Victoria
    Enheten för externa relationer, Umeå universitet, Sweden.
    Värbrand, Peter
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Vägen till samverkanssäkrad utbildning. [2]: Möjligheter och utmaningar2016Book (Other academic)
    Abstract [sv]

    Universitet och högskolor bidrar till samhällsutvecklingen genom att forskningsbaserad kunskap tillämpas av olika aktörer i samhället. För att möta dagens och morgondagens samhällsutmaningar utgör således kunskapsutbyte och samverkan mellan lärosäten och samhället en värdefull möjlighet. Att ha starka relationer med samhällets aktörer identifieras också som viktigt i utvecklingen av ett internationellt starkt lärosäte.

    Samverkan i högre utbildning främjar samhällets förändringsförmåga och stärker utbildningens kvalitet, men samverkan förbereder också studenterna för ett livslångt lärande och underlättar övergången mellan utbildning och arbetsliv. Ett lärosäte i nära samverkan med aktörer i samhället är ett relevant lärosäte, det vill säga ett lärosäte som är till nytta för sin omvärld och för sina medarbetare och studenter.

    Ett grundläggande problem vad gäller möjligheterna att integrera samverkan i akademisk utbildning står att finna i statens fördelning av medel till lärosätena. De statliga medlen utgår nämligen i två separata anslag, ett vardera för de båda huvuduppdragen utbildning och forskning. Samverkan kan sägas ingå i bägge uppdragen. Till skillnad från forskningssamverkan finns det för utbildningssamverkan ingen särskild uppföljning och inte heller några ekonomiska incitament. Utvärdering av forskning och utbildning bör således breddas så att kvalitetsstärkande samverkansinslag också inkluderas i resursfördelningsprinciperna. Statens bristande strukturer för fördelning och uppföljning återspeglas i hur lärosätena fördelar resurser till och följer upp samverkan: lärare ges sällan resurser (i form av särskild tid) för att på ett pedagogiskt genomtänkt sätt kunna inkludera samverkansinslag i undervisningen; samverkan är sällan meriterande eller lönegrundande; och den utbildningssamverkan som bedrivs följs sällan upp – varken på institutions-, fakultets- eller lärosätesnivå. Samma sak kan sägas gälla på nationell nivå – det samverkande lärosätet erhåller inga extra anslag och det bestraffas ej heller för försummelse av detsamma. Att göra samverkan till en integrerad del av utbildningen innebär att samverkan bör ingå i de pedagogiska modeller som lärare använder för att leda studenternas kunskapsutveckling mot de mål som finns angivna i kurs- och utbildningsplaner. Det betyder också att arbetet med samverkan bör inkluderas i processer för styrning, planering och uppföljning av utbildning och undervisning på såväl kurs- och programnivå som på institutions-, fakultets- och lärosätesnivå. Att göra samverkan till en integrerad del av utbildningen är att sträva mot att externa aktörer ska bli en självklar del i den dagliga verksamheten – för studenter såväl som för medarbetare och för de organisationer man samverkar med. För att svenska lärosäten ska ges en realistisk möjlighet att göra samverkan till en integrerad del av utbildningsverksamheten krävs det framför allt följande:

    • att politiker och departement utformar ett fördelningssystem där framgångsrika samverkansinsatser inom utbildningen leder till en förstärkning av resursbasen på lärosätena;
    • att lärosätesledningar tar tydlig ställning för samverkansfrågan i sina strategiska styrdokument och att samverkan införs i lärosätenas kvalitetssäkringssystem för utbildning, samt att lärosätena inför system för att styra och följa upp samverkan i utbildningen på lärosätesövergripande nivå;
    • att ledningen för fakulteter, institutioner eller motsvarande omsätter lärosätets strategiska åtaganden i handlingsplaner och lokala styrdokument samt utformar system för dokumentation, styrning och uppföljning av samverkan i utbildningsprogram;
    • att lärare samt kurs- och programansvariga inför samverkan i utbildningens styrande dokument (t.ex. kurs- och utbildningsplaner) samt i den ordinarie undervisningsverksamheten.

    Dessutom bör lärosätena – både gemensamt men också vart och ett för sig – införa system och karriärvägar där medarbetares insatser i det vardagliga samverkansarbetet uppmärksammas och belönas.

    Mot bakgrund av detta kan man konstatera att det är angeläget att lärosätenas strategiska arbete avseende utveckling och uppföljning av samverkan i utbildningen vidareutvecklas. Men, med vilka verktyg, var i verksamheten och på vilka sätt?

    I följande skrift samlas erfarenheter och goda exempel gjorda inom ramen för ett flerårigt lärosätesövergripande samarbetsprojekt, Samverkanssäkrade utbildningsprogram, där utgångspunkten har varit att identifiera strategier och metoder för att integrera samverkan i utbildningsprogram. Målet har varit att undersöka och beskriva hur samverkan kan vara ett medel som bidrar till att stärka utbildningens kvalitet och relevans, samt ge förslag på hur vägen till samverkanssäkrad utbildning kan se ut.

    Den centrala slutsatsen är att samverkan, när den är en integrerad del av utbildningen, bidrar till kvalitet och säkerställer att utbildningen blir till nytta för samhället. Det finns också andra vinster med att bedriva ett systematiskt samverkansarbete, till exempel att det leder till pedagogisk utveckling för undervisande personal, att det ökar förutsättningarna för ett utmaningsbaserat lärande med studenten i centrum, att det underlättar övergången från studier till arbetsliv, och att det möjliggör fördjupade relationer med den värld lärosätet finns i. Resan mot samverkanssäkrad utbildning är, med andra ord, mödan väl värd.

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  • 20.
    Ahlin, Katarina
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Bredin, Sanna
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    European Aviation Crisis Management2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Our aim is to investigate and evaluate the efficiency of crisis management in European aviation, and to recommend enhancements. To fulfill this, we mapped the current crisis management plans and created a fictive scenario where a cyber-attack shut down the power at five of the major airports in Europe. Air traffic in Europe was reconstructed to a chosen day; the 16th of September 2013, and the reconstructed traffic situation was used in the scenario. We also created a model, for the purpose of showing the effect of a cut in time for the steps in the crisis management plan may have on the traffic waiting to depart at the closed airports. When using these means, we could implement the crisis management plans on the fictive scenario and make changes to the plans for a new implementation. The existing crisis management plans were compared to the modified plans made by us, and it was found that usage of a common platform for the different stakeholders involved in the crisis could improve the efficiency of the crisis management.

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    fulltext
  • 21.
    Ahlström, Mattias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Development of an Attractive Network for Regional Bus Traffic in Dalarna County2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Även om direktbusstrafiken i Dalarnas län redan i dagsläget trafikerar relativt raka och snabba linjesträckningar anser länstrafikbolaget Dalatrafik att det finns potential till att ytterligare sänka restiderna för att locka fler resenärer. Fyra av länets viktigaste direktbusslinjer har därför studerats och för var och en av dessa har ett antal förändringsåtgärder tagits fram. Målet med förändringsåtgärderna har varit att, i första hand, åstadkomma en rakare linjesträckning och utreda hur mycket restiden skulle komma att förändras om bussen istället kör den nya vägen. Utifrån befintlig resandestatistik över hur många resenärer som reser på varje sträcka har den totala tidsbesparingen för samtliga förändringsåtgärder per linje beräknats och detta har givits ett monetärt värde. Genom täckningsanalyser har befolkningen inom upptagningsområdet kring varje hållplats beräknats, detta för att visa hur tillgängligheten till respektive linje förändras efter ett eventuellt införande av de föreslagna åtgärderna.

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    fulltext
  • 22.
    Ahmad, Ban
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Vieglins, Gustav
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A energy and cost comparison between a BBR and a passive apartment building2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Idag ställer samhället och konsumenterna allt större krav på klimatsmarta boenden för att minska energianvändningen. Trots det byggs fortfarande till stor del traditionella hus efter Boverkets byggregler. På uppdrag av WSP studerar denna rapport hur energiåtgången hos ett befintligt flerbostadshus i Stockholm, byggt efter BBR, hade sett ut om det uppförts för att fylla kravspecifikationen för passivhus enligt FEBY12. Samt hur livscykelkostnaderna hade skiljt sig för de två husen.

    Studien inleddes med en datainsamling av för det befintliga flerbostadshusets areor samt Uvärdena och följs upp med simuleringar av flerbostadshuset i beräkningsprogrammet Energihuskalkyl. Datorberäkningarna jämfördes med manuella beräkningar för att säkerställa värmeförlusttalet samt andelen köpt energi. Varefter flerbostadshuset anpassades med Kingspans detaljbibliotek för att uppfylla FEBY12s passivhuskrav och följdes upp med samma dator- och manuella beräkningar. Där de båda resultaten presenteras och jämförs.

    I rapportens andra del undersöks och jämförs de två flerbostadshusens livscykelkostnader, sett till investerings-, drifts- och underhållskostnader. Då beställaren sekretessbelagt de verkliga kostnaderna antogs de verkliga kostnaderna för det befintliga huset från Statistiska Centralbyrån. För att beräkna det teoretiska passivhusets investeringskostnader beräknades materialkostnaderna för de båda husen efter de givna ritningarna. Där skillnaden i materialkostnaderna adderades till investeringskostnaden för det passiva flerbostadshuset.

    Underhållskostnaderna antogs till detsamma för det passiva flerbostadshuset samtidigt som att driftskostnaderna sänktes procentuellt med den minskade mängden köpt energi från energiberäkningarna.

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  • 23.
    Ahola, David
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Yin To, Jie
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    To be entered/Green Cargo2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Schemakonstruktion för järnvägspersonal är en stor utmaning. En orsak är att arbetsuppgifterna vid järnvägen kräver olika kunskaps- och kompetenskrav, samt att det finns många arbetsregler som utgör restriktioner för schemakonstruktionen. I detta examensarbete har en fallstudie utförts för datorstödd schemakonstruktion för personalbemanning. Examensarbetet har utförts vid avdelningen för bemanningsplanering som ansvarar för planering av personal vid två av Green Cargos olika bangårdar. Huvudsyftet med det här examensarbetet är att utreda skillnaderna i scheman som skapats manuellt respektive automatiskt med hjälp av programvaran BP. Schemajämförelserna ska också redovisa nyttan av det automatiska planeringssättet där det finns applicerat. Under arbetet genomfördes litteraturstudier samt en fallstudie. I fallstudien genomfördes testkörningar med olika schemakonstruktionsmetoder på två bangårdar. Det numeriska resultatet visar att den datorassisterade bemanningsmetoden innebär en förbättrad bemanningsplanering ur företagets synvinkel då produktionsbehovet kan täckas utan ökade kostnader. Detta innebär också en ökad flexibilitet i produktionsplaneringen då tjänstgöringsturer enkelt kan ändras. Det gör det också mycket enklare att tilldela personal olika arbetsuppgifter som de har kompetens för. Den optimeringsbaserade bemanningsplanen innebär inte en ökad arbetsbelastning för medarbetaren. Trots att fler bangårdstjänster kan bemannas genom att använda den datorassisterade metoden visar det sig att den totala utlagda arbetstiden inte alls ökar eller att den bara ökar marginellt för vissa medarbetare. När planering sker med programvaran styrs denna av parametrar som är lätta att ändra. Dessa inställningar av parametrar är avgörande för utseendet på schemat. Indata kan vara fridagsplanering, kompetenstillgång och produktionsbehov. De i sin tur avgör i betydande grad på hur balansen mellan livs- och ekonomiska kvalitetsmåtten ser ut för medarbetarna.

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  • 24.
    Aichholzer, Oswin
    et al.
    Graz University of Technology.
    Akitaya, Hugo
    Tufts University.
    Cheung, Kenny
    NASA Ames Research Center.
    Demaine, Erik
    Massachusetts Institute of Technology.
    Demaine, Martin
    Massachusetts Institute of Technology.
    Fekete, Sándor
    TU Braunschweig.
    Kleist, Linda
    TU Braunschweig.
    Kostitsyna, Irina
    TU Eindhoven.
    Löffler, Maarten
    Universiteit Utrecht.
    Masárová, Zuzana
    IST Austria.
    Mundilova, Klara
    Massachusetts Institute of Technology.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Folding Polyominoes with Holes into a Cube2019Conference paper (Refereed)
  • 25.
    Aichholzer, Oswin
    et al.
    Institute for Software Technology, Graz University of Technology, Austria.
    Akitaya, Hugo
    School of Computer Science, Carleton University, Canada.
    Cheung, Kenny
    NASA Ames Research Center, United States of America.
    Demaine, Erik
    CSAIL, Massachusetts Institute of Technology, United States of America.
    Demaine, Martin
    CSAIL, Massachusetts Institute of Technology, United States of America.
    Fekete, Sándor P.
    Department of Computer Science, TU Braunschweig, Germany.
    Kleist, Linda
    Department of Computer Science, TU Braunschweig, Germany.
    Kostitsyna, Irina
    Mathematics and Computer Science Department, TU Eindhoven, Netherlands.
    Löffler, Maarten
    Department of Information and Computing Science, Universiteit Utrecht, Netherlands.
    Masárová, Zuzana
    IST Austria, Klosterneuburg, Austria.
    Mundilova, Klara
    CSAIL, Massachusetts Institute of Technology, United States of America.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Folding Polyominoes with Holes into a Cube2021In: Computational geometry, ISSN 0925-7721, E-ISSN 1879-081X, Vol. 93, article id 101700Article in journal (Refereed)
    Abstract [en]

    When can a polyomino piece of paper be folded into a unit cube? Prior work studied tree-like polyominoes, but polyominoes with holes remain an intriguing open problem. We present sufficient conditions for a polyomino with one or several holes to fold into a cube, and conditions under which cube folding is impossible. In particular, we show that all but five special “basic” holes guarantee foldability.

  • 26. Aichholzer, Oswin
    et al.
    Biro, Michael
    Demaine, Erik
    Demaine, Martin
    Eppstein, David
    Fekete, Sándor P.
    Hesterberg, Adam
    Kostitsyna, Irina
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Folding Polyominoes into (Poly)CubesIn: International journal of computational geometry and applications, ISSN 0218-1959Article in journal (Refereed)
  • 27.
    Aijaz, Adnan
    et al.
    Toshiba Europe Ltd, England.
    Dawy, Zaher
    Amer Univ Beirut, Lebanon.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Simsek, Meryem
    Int Comp Sci Inst Berkeley, CA USA.
    Oteafy, Sharief
    Depaul Univ, IL 60604 USA.
    Holland, Oliver
    Adv Wireless Technol Grp Ltd, England.
    The IEEE P1918.1 Reference Architecture Framework for the Tactile Internet and a Case Study2020In: 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE , 2020Conference paper (Refereed)
    Abstract [en]

    The term Tactile Internet broadly refers to a communication network that is capable of delivering control, touch, and sensing/actuation information in real-time. The Tactile Internet is currently a topic of interest for various standardization bodies. The emerging IEEE P1918.1 standards working group is focusing on defining a framework for the Tactile Internet. The main objective of this work is to present the IEEE P1918.1 reference architecture framework for the Tactile Internet. The paper provides an in-depth survey of various architectural aspects including the key entities, the interfaces, the functional capabilities, and the protocol stack. A case study has been presented as a manifestation of the architecture. Performance evaluation demonstrates the impact of functional capabilities and the underlying enablers on user-level utility pertaining to a generic Tactile Internet application.

  • 28. Order onlineBuy this publication >>
    Ait Ali, Abderrahman
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Methods for Capacity Allocation in Deregulated Railway Markets2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Faced with increasing challenges, railways around Europe have recently undergone major reforms aiming to improve the efficiency and competitiveness of the railway sector. New market structures such as vertical separation, deregulation and open access can allow for reduced public expenditures, increased market competition, and more efficient railway systems.

    However, these structures have introduced new challenges for managing infrastructure and operations. Railway capacity allocation, previously internally performed within monopolistic national companies, are now conferred to an infrastructure manager. The manager is responsible for transparent and efficient allocation of available capacity to the different (often competing) licensed railway undertakings.

    This thesis aims at developing a number of methods that can help allocate capacity in a deregulated (vertically separated) railway market. It focuses on efficiency in terms of social welfare, and transparency in terms of clarity and fairness. The work is concerned with successive allocation of capacity for publicly controlled and commercial traffic within a segmented railway market.

    The contributions include cost benefit analysis methods that allow public transport authorities to assess the social welfare of their traffic, and create efficient schedules. The thesis also describes a market-based transparent capacity allocation where infrastructure managers price commercial train paths to solve capacity conflicts with publicly controlled traffic. Additionally, solution methods are developed to help estimate passenger demand, which is a necessary input both for resolving conflicts, and for creating efficient timetables.

    Future capacity allocation in deregulated markets may include solution methods from this thesis. However, further experimentations are still required to address concerns such as data, legislation and acceptability. Moreover, future works can include prototyping and pilot projects on the proposed solutions, and investigating legal and digitalisation strategies to facilitate the implementation of such solutions.

    List of papers
    1. European Railway Deregulation: An overview of market organization and capacity allocation
    Open this publication in new window or tab >>European Railway Deregulation: An overview of market organization and capacity allocation
    2022 (English)In: Transportmetrica A: Transport Science, ISSN 2324-9935, E-ISSN 2324-9943, Vol. 18, no 3, p. 594-618Article in journal (Refereed) Published
    Abstract [en]

    Railway markets in Europe have been reorganized to allow competition between different operators. Thus, European railways have been vertically separated, separating infrastructure management from provisions of train services. This allows several train operators to compete for passengers and freight services. Different ways have emerged for vertical separation, capacity allocation and track access charges. This paper reviews, compares and discusses important deregulation aspects, using examples from a number of European countries to show different possible solutions. The study describes how competition has been introduced and regulated, with a particular focus on describing the different ways capacity is allocated and how conflicting requests by different train operators are resolved. It also reviews the related issue of how access charges are constructed and applied. Although guided by the same European legislation, we conclude that the studied railways have different deregulation outcomes, e.g., market organization, capacity allocation. Besides, few countries have so far managed to create efficient and transparent processes for allocating capacity between competing train operators. Although allowed by the legislation, market-based allocation is absent or never used. In order to foster more competition which can yield substantial social benefits, the survey indicates that most European railways still need to develop and experiment with more efficient and transparent capacity allocation procedures.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2022
    Keywords
    Railway deregulation, Vertical separation, Competition, Capacity allocation, Access charges
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-173445 (URN)10.1080/23249935.2021.1885521 (DOI)000621709500001 ()
    Note

    Funding: This research is part of the project Socio-economically efficient allocation of railway capacity, SamEff (Samhallsekonomiskt effektiv tilldelning av kapacitet pa jarnvagar) which is funded by a grant from the Swedish Transport Administration (Trafikverket). The authors are grateful to Jan-Eric Nilsson and Yves Crozet for reference recommendations as well as Russell Pittman, Steven Harrod, Roger Pyddoke and several anonymous reviewers for the valuable discussions and comments.

    Available from: 2021-02-19 Created: 2021-02-19 Last updated: 2022-10-17
    2. Pricing commercial train path requests based on societal costs
    Open this publication in new window or tab >>Pricing commercial train path requests based on societal costs
    2020 (English)In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 132, p. 452-464Article in journal (Refereed) Published
    Abstract [en]

    On deregulated railway markets, efficient capacity allocation is important. We study the case where commercial trains and publicly controlled traffic (“commuter trains”) use the same railway infrastructure and hence compete for capacity. We develop a method that can be used by an infrastructure manager trying to allocate capacity in a socially efficient way. The method calculates the loss of societal benefits incurred by changing the commuter train timetable to accommodate a commercial train path request, and based on this calculates a reservation price for the train path request. If the commercial operator’s willingness-to-pay for the train path exceeds the loss of societal benefits, its request is approved. The calculation of these benefits takes into account changes in commuter train passengers’ travel times, waiting times, transfers and crowding, and changes in operating costs for the commuter train operator(s). The method is implemented in a microscopic simulation program, which makes it possible to test the robustness and feasibility of timetable alternatives. We show that the method is possible to apply in practice by demonstrating it in a case study from Stockholm, illustrating the magnitudes of the resulting commercial train path prices. We conclude that marginal societal costs of railway capacity in Stockholm are considerably higher than the current track access charges.

    Place, publisher, year, edition, pages
    Elsevier, 2020
    Keywords
    Train timetables, Train conflicts, Capacity pricing, Railway capacity, Capacity allocation
    National Category
    Economics
    Identifiers
    urn:nbn:se:liu:diva-162784 (URN)10.1016/j.tra.2019.12.005 (DOI)000514014700030 ()2-s2.0-85076736383 (Scopus ID)
    Projects
    SamEff
    Note

    Funding agencies:  Swedish Transport Administration (Trafikverket) [Samhallsekonomiskt effektiv tilldelning av kapacitet pa jarnvagar]

    The accepted version is also available on the author's home page: 

    http://abdeaitali.github.io/

    Available from: 2019-12-18 Created: 2019-12-18 Last updated: 2021-12-01Bibliographically approved
    3. Are commuter train timetables consistent with passengers' valuations of waiting times and in-vehicle crowding?
    Open this publication in new window or tab >>Are commuter train timetables consistent with passengers' valuations of waiting times and in-vehicle crowding?
    2022 (English)In: Transport Policy, ISSN 0967-070X, E-ISSN 1879-310X, Vol. 116, p. 188-198Article in journal (Refereed) Published
    Abstract [en]

    Social cost-benefit analysis is often used to analyse transport investments, and can also be used for transport operation planning and capacity allocation. If it is to be used for resolving capacity conflicts, however, it is important to know whether transit agencies' timetable requests are consistent with the cost-benefit framework, which is based on passenger preferences. We show how a public transport agency's implicit valuations of waiting time and crowding can be estimated by analysing timetables, apply the method to commuter train timetables in Stockholm, and compare the implicit valuations to the corresponding passenger valuations in the official Swedish cost-benefit analysis guidelines. The results suggest that the agency puts a slightly lower value on waiting time and crowding than the passenger valuations codified in the official guidelines. We discuss possible reasons for this and implications for using cost-benefit analysis for capacity allocation. We also find that optimal frequencies are more sensitive to the waiting time valuation than to that of crowding.

    Place, publisher, year, edition, pages
    Elsevier, 2022
    Keywords
    Waiting time, Crowding, Cost-benefit analysis, Implicit preference, Commuter train
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-181610 (URN)10.1016/j.tranpol.2021.11.025 (DOI)000751667100001 ()
    Projects
    SamEff
    Funder
    Swedish Transport Administration
    Note

    Funding: Swedish Transport Administration (Trafikverket) [samhadllsekonomiskt effektiv tilldelning av kapacitet pa jadrnvadgar]

    Available from: 2021-12-03 Created: 2021-12-03 Last updated: 2023-01-10Bibliographically approved
    4. A disaggregate bundle method for train timetabling problems
    Open this publication in new window or tab >>A disaggregate bundle method for train timetabling problems
    Show others...
    2020 (English)In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 16, article id 100200Article in journal (Refereed) Published
    Abstract [en]

    The train timetabling problem (TTP) consists of finding a feasible timetable for a number of trains which minimises some objective function, e.g., sum of running times or deviations from ideal departure times. One solution approach is to solve the dual problem of the TTP using so-called bundle methods. This paper presents a new bundle method that uses disaggregate data, as opposed to the standard bundle method which in a certain sense relies on aggregate data. We compare the disaggregate and aggregate methods on realistic train timetabling scenarios from the Iron Ore line in Northern Sweden. Numerical results indicate that the proposed disaggregate method reaches better solutions faster than the standard aggregate approach.

    Keywords
    Train timetabling, Disaggregation, Bundle methods, Lagrangian relaxation, Mathematical programming
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-165781 (URN)10.1016/j.jrtpm.2020.100200 (DOI)000597313000002 ()
    Projects
    SamEff
    Funder
    Swedish Transport Administration
    Note

    The accepted version is also available on the author's home page: 

    http://abdeaitali.github.io/

    Funding agencies: Swedish Transport Administration (Trafikverket)

    Available from: 2020-05-24 Created: 2020-05-24 Last updated: 2021-12-01
    5. The value of additional data for public transport origin–destination matrix estimation
    Open this publication in new window or tab >>The value of additional data for public transport origin–destination matrix estimation
    2022 (English)In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 14, no 2, p. 419-439Article in journal (Refereed) Published
    Abstract [en]

    Passenger origin–destination data is an important input for public transport planning. In recent years, new data sources have become increasingly common through the use of the automatic collection of entry counts, exit counts and link flows. However, collecting such data can be sometimes costly. The value of additional data collection hence has to be weighed against its costs. We study the value of additional data for estimating time-dependent origin–destination matrices, using a case study from the London Piccadilly underground line. Our focus is on how the precision of the estimated matrix increases when additional data on link flow, destination count and/or average travel distance is added, starting from origin counts only. We concentrate on the precision of the most policy-relevant estimation outputs, namely, link flows and station exit flows. Our results suggest that link flows are harder to estimate than exit flows, and only using entry and exit data is far from enough to estimate link flows with any precision. Information about the average trip distance adds greatly to the estimation precision. The marginal value of additional destination counts decreases only slowly, so a relatively large number of exit station measurement points seem warranted. Link flow data for a subset of links hardly add to the precision, especially if other data have already been added.

    Place, publisher, year, edition, pages
    Springer, 2022
    Keywords
    Dynamic origin-destination; OD estimation; entropy maximization; lagrangian relaxation; smart card; public transport
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-179343 (URN)10.1007/s12469-021-00282-0 (DOI)000695756100001 ()
    Projects
    SamEff
    Funder
    Swedish Transport Administration
    Note

    Funding: Swedish National Road and Transport Research Institute (VTI); Swedish Transport Administration (Trafikverket)

    Available from: 2021-09-19 Created: 2021-09-19 Last updated: 2022-10-14
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    presentationsbild
  • 29.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. VTI Swedish National Road and Transport Research Institute, Transport Economics, Stockholm.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    European Railway Deregulation: An overview of market organization and capacity allocation2022In: Transportmetrica A: Transport Science, ISSN 2324-9935, E-ISSN 2324-9943, Vol. 18, no 3, p. 594-618Article in journal (Refereed)
    Abstract [en]

    Railway markets in Europe have been reorganized to allow competition between different operators. Thus, European railways have been vertically separated, separating infrastructure management from provisions of train services. This allows several train operators to compete for passengers and freight services. Different ways have emerged for vertical separation, capacity allocation and track access charges. This paper reviews, compares and discusses important deregulation aspects, using examples from a number of European countries to show different possible solutions. The study describes how competition has been introduced and regulated, with a particular focus on describing the different ways capacity is allocated and how conflicting requests by different train operators are resolved. It also reviews the related issue of how access charges are constructed and applied. Although guided by the same European legislation, we conclude that the studied railways have different deregulation outcomes, e.g., market organization, capacity allocation. Besides, few countries have so far managed to create efficient and transparent processes for allocating capacity between competing train operators. Although allowed by the legislation, market-based allocation is absent or never used. In order to foster more competition which can yield substantial social benefits, the survey indicates that most European railways still need to develop and experiment with more efficient and transparent capacity allocation procedures.

    Download full text (pdf)
    fulltext
  • 30.
    Ait Ali, Abderrahman
    et al.
    The Swedish National Road and Transport Research Institute (VTI), Stockholm, Sweden.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The value of additional data for public transport origin–destination matrix estimation2022In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 14, no 2, p. 419-439Article in journal (Refereed)
    Abstract [en]

    Passenger origin–destination data is an important input for public transport planning. In recent years, new data sources have become increasingly common through the use of the automatic collection of entry counts, exit counts and link flows. However, collecting such data can be sometimes costly. The value of additional data collection hence has to be weighed against its costs. We study the value of additional data for estimating time-dependent origin–destination matrices, using a case study from the London Piccadilly underground line. Our focus is on how the precision of the estimated matrix increases when additional data on link flow, destination count and/or average travel distance is added, starting from origin counts only. We concentrate on the precision of the most policy-relevant estimation outputs, namely, link flows and station exit flows. Our results suggest that link flows are harder to estimate than exit flows, and only using entry and exit data is far from enough to estimate link flows with any precision. Information about the average trip distance adds greatly to the estimation precision. The marginal value of additional destination counts decreases only slowly, so a relatively large number of exit station measurement points seem warranted. Link flow data for a subset of links hardly add to the precision, especially if other data have already been added.

    Download full text (pdf)
    fulltext
  • 31.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transport Research Institute (VTI), Stockholm.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish Transport Administration (Trafikverket), Solna.
    Warg, Jennifer
    Royal Institute of Technology (KTH), Stockholm.
    Are commuter train timetables consistent with passengers' valuations of waiting times and in-vehicle crowding?2022In: Transport Policy, ISSN 0967-070X, E-ISSN 1879-310X, Vol. 116, p. 188-198Article in journal (Refereed)
    Abstract [en]

    Social cost-benefit analysis is often used to analyse transport investments, and can also be used for transport operation planning and capacity allocation. If it is to be used for resolving capacity conflicts, however, it is important to know whether transit agencies' timetable requests are consistent with the cost-benefit framework, which is based on passenger preferences. We show how a public transport agency's implicit valuations of waiting time and crowding can be estimated by analysing timetables, apply the method to commuter train timetables in Stockholm, and compare the implicit valuations to the corresponding passenger valuations in the official Swedish cost-benefit analysis guidelines. The results suggest that the agency puts a slightly lower value on waiting time and crowding than the passenger valuations codified in the official guidelines. We discuss possible reasons for this and implications for using cost-benefit analysis for capacity allocation. We also find that optimal frequencies are more sensitive to the waiting time valuation than to that of crowding.

    Download full text (pdf)
    fulltext
  • 32.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. VTI.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Trafikverket.
    Warg, Jennifer
    KTH.
    Measuring the Socio-economic Benefits of Train Timetables: Application to Commuter Train Services in Stockholm2017In: / [ed] Domokos Esztergár-Kiss, Tamás Mátrai, János Tóth, István Varga, 2017, Vol. 27, p. 849-856Conference paper (Refereed)
    Abstract [en]

    On highly used railway lines with heterogeneous traffic, timetabling is challenging. In particular, the limited existing capacity means that to guarantee an acceptable level of quality, the infrastructure manager must cancel some train services on the expense of others. In this article, we study the conflict between commercial long-distance trains and subsidized commuter trains with a socio-economic perspective (i.e. travelers and train operators). The study attempts to answer the following question: What is the socio-economic effect of modifying the timetable of a commuter service?

    The case study treats the commuter train services in Stockholm. Trip data was collected from the local commuter train operator. An entropy maximization-based model was implemented to estimate the dynamic network Origin-Destination (OD) matrix. This dynamic matrix, of one full working day, was then used to estimate the number of travelers per train, and further converted for use in the microscopic simulation tool RailSys. Travel and waiting time are estimated for each OD pair and with that the generalized costs for the travelers and operators. The effect of crowding in the trains is included in the estimation. The article can be considered as an initiation to a novel method to calculate effects of changes in commuter train timetables. This novel approach enables to price commercial train slots in the capacity allocation process such as in an auction. It provides a new way to estimate the local train operator´s valuation of the different parameters (i.e. waiting, travel time and interchanges). Using RailSys for the estimation of times makes it possible to include capacity aspects that normally are difficult to reveal.

  • 33.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish Natl Rd & Transport Res Inst VTI, Sweden.
    Lidén, Tomas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish Natl Rd & Transport Res Inst VTI, Sweden.
    Minimal utilization rate for railway maintenance windows: a cost-benefit approach2022In: European Journal of Transport and Infrastructure Research, ISSN 1567-7133, E-ISSN 1567-7141, Vol. 22, no 2, p. 108-131Article in journal (Refereed)
    Abstract [en]

    Methods for economic assessment are often used in the rail sector to evaluate large infrastructure investments such as new high-speed lines. With larger networks and ageing infrastructure, these methods can also be used for planning maintenance. In this paper, we focus on the newly introduced concept of maintenance windows in Sweden. These are pre-allocated slots in the train timetable dedicated to performing, among others, periodic/frequent maintenance activities. To justify the pre-allocation of such windows, this study presents a method to find minimal utilization rates depending on window designs and traffic situations. Using a cost-benefit approach, the windows are assessed using a total social cost including work costs, loss in traffic production and reliability gains in future traffic. Based on a case study from the Southern main line in Sweden, we study the minimal utilization rate in different test scenarios, i.e., night or day shifts, asset degradation functions and designs of maintenance windows. The results show that lower utilization rates (4-42%) can be accepted during low-volume traffic or for partial closures, while higher utilization rates (47-83%) are required for full closures during high-volume traffic. Whether the rates are measured as the share of used window time or the share of utilized windows is less important, especially when higher utilization is required. Sensitivity analyses of asset knowledge indicate that parameters such as asset degradation function and minimum asset quality (and to a lesser extent traffic volume, discount rate and failure likelihood) can have a substantial effect on the minimum required utilization rates.

  • 34.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transport Research Institute (VTI), Sweden.
    Lindberg, Per Olov
    Swedish National Road and Transport Research Institute (VTI), Sweden.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Nilsson, Jan-Eric
    Swedish National Road and Transport Research Institute (VTI), Sweden.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A disaggregate bundle method for train timetabling problems2020In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 16, article id 100200Article in journal (Refereed)
    Abstract [en]

    The train timetabling problem (TTP) consists of finding a feasible timetable for a number of trains which minimises some objective function, e.g., sum of running times or deviations from ideal departure times. One solution approach is to solve the dual problem of the TTP using so-called bundle methods. This paper presents a new bundle method that uses disaggregate data, as opposed to the standard bundle method which in a certain sense relies on aggregate data. We compare the disaggregate and aggregate methods on realistic train timetabling scenarios from the Iron Ore line in Northern Sweden. Numerical results indicate that the proposed disaggregate method reaches better solutions faster than the standard aggregate approach.

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  • 35.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Värdering av trafikinformationsnyttor i tågtrafiken (VTT): slutrapport2024Report (Other academic)
    Abstract [en]

    Train delays with increasing demand result in substantial social costs. One way to reduce these costs is through efficient communication of various types of traffic information to passengers. Depending on which/when information is received, passengers’ behavioral adaptations reduce their travel costs especially in the event of delays.This project aims at calculating the social benefits of such traffic information. The purpose is to develop a quantitative model to quantify the value of communicating information to passengers in cases of train delays.Using different disruption scenarios in a case study from Stockholm commuter train services, the study provides insights to the infrastructure manager on the social value of such information systems as part of the large infrastructure investments. These insights can also help design more effective information strategies to reduce social costs of train disruptions.

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  • 36.
    Ait Ali, Abderrahman
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. VTI.
    Warg, Jennifer
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pricing commercial train path requests based on societal costs2020In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 132, p. 452-464Article in journal (Refereed)
    Abstract [en]

    On deregulated railway markets, efficient capacity allocation is important. We study the case where commercial trains and publicly controlled traffic (“commuter trains”) use the same railway infrastructure and hence compete for capacity. We develop a method that can be used by an infrastructure manager trying to allocate capacity in a socially efficient way. The method calculates the loss of societal benefits incurred by changing the commuter train timetable to accommodate a commercial train path request, and based on this calculates a reservation price for the train path request. If the commercial operator’s willingness-to-pay for the train path exceeds the loss of societal benefits, its request is approved. The calculation of these benefits takes into account changes in commuter train passengers’ travel times, waiting times, transfers and crowding, and changes in operating costs for the commuter train operator(s). The method is implemented in a microscopic simulation program, which makes it possible to test the robustness and feasibility of timetable alternatives. We show that the method is possible to apply in practice by demonstrating it in a case study from Stockholm, illustrating the magnitudes of the resulting commercial train path prices. We conclude that marginal societal costs of railway capacity in Stockholm are considerably higher than the current track access charges.

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  • 37.
    Ait-Ali, Abderrahman
    Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Assessing the Use of Welfare-Based Track Access Charging for Railway Capacity Allocation2019Conference paper (Other academic)
    Abstract [en]

    The deregulation of railway markets has brought new challenges to the capacity allocation process. In this context, we present a new hybrid methodology for allocating railway capacity to commercial train operators. Commercial freight or passenger train operators compete with each other as well as with subsidised local commuter trains. In the method presented in this article, minimal track access charges are computed using a social cost-benefit analysis of alternative commuter train timetables. These minimal charges are used as a starting or reservation price in an auction-based method for capacity allocation between the commercial operators. The aim of this study is to assess the use of such a welfare-based track access charging system in a real case scenario. On a congested line in the region of Stockholm, we evaluate the welfare-based access charges of commercial operators. We show that the new methodology can be used to allocate capacity between subsidized and commercial train operators. Moreover, we provide an estimate of the marginal minimal access charge per train path that the commercial operators request.

  • 38.
    Akililu, Meaza Negash
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Verification of Rural Traffic Simulator, RuTSim 22012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Traffic models based on micro-simulation are becoming increasingly important as traffic analysistools. Due to the detailed traffic description, different micro-simulation models are needed tosimulate different traffic environments. The Rural Traffic Simulator, RuTSim, is a unique microtrafficsimulation model for traffic on rural roads. RuTSim is developed at VTI with support fromthe Swedish Transport Administration. Currently, a new version of the RuTSim model has beenimplemented based on the earlier one but with some enhancements. Due to these enhancements,the new implementation of RuTSim should be verified before being used to analyze real worldproblems.

    In this master’s thesis, a verification of the new implementation of the RuTSim model, RuTSim 2,has been carried out. This paper includes a description of traffic micro-simulation models forrural roads in general and a description of RuTSim model in particular. Common verificationtechniques of the simulation models are also discussed in this study.

    Based on the theoretical assessments, a model-to-model comparison verification scheme isselected to verify the RuTSim 2 model. That is, the model verification is performed by comparingthe simulation outputs from RuTSim 2 to the old version of RuTSim (RuTSim 1), since RuTSim1 is well verified and calibrated. Statistical hypothesis tests are used to check whether the meanand standard deviation differences of the simulation outputs between the two simulators aresignificant or not.

    Based on the verification results, the new version of the RuTSim model has comparable modelingof vehicle-vehicle and vehicle-infrastructure interactions as the old version. Furthermore, thehypothesis test results show that the differences of the mean simulation results of the twosimulators are not significant. Therefore, the new implementation of RuTSim model, RuTSim 2,has been proven to be equivalent model as the old version.

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  • 39.
    Akitaya, Hugo
    et al.
    Department of Computer Science, University of Massachusetts Lowell, Lowell, Massachusetts, United States.
    Ballinger, Brad
    Humbolt State University, Arcata, California, United States.
    Demaine, Erik
    Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States.
    Hull, Thomas
    Department of Mathematics, Western New England University, Springfield, Massachusetts, United States.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Folding Points to a Point and Lines to a Line2021Conference paper (Refereed)
  • 40.
    Al Haji, Ghazwan
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Fowler, Scott
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson Granberg, Tobias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Smart traffic calming measures for smart cities: a pre-study2018Report (Other academic)
    Abstract [en]

    Traffic calming measures, such as speed bumps and elevated crossing points, are used to reduce speed, to prevent overtaking and generally contribute to a safer traffic situation. However, they might also cause increased response times for rescue vehicles (e.g. ambulances or fire trucks). An alternative to the conventional traffic calming measures is so-called smart traffic calming measures. These can determine when a vehicle approaches, whose journey should not be hindered, and adjust to allow for free passage for this vehicle.

    This report gives an overview of the problem, and some examples of smart  traffic calming measures are discussed. Special focus is put on the wireless communication necessary to detect emergency vehicles. Furthermore, existing challenges and possible solutions for traffic calming measures and the communication needed to make them smart are discussed.

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    Smart traffic calming measures for smart cities - a pre-study
  • 41.
    Al-Ameri, Haitham
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Effektivisering av bygglogistik: Utmaningar2022Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Carrying instruments and different political goals have given rise to variation of the construction investments. This has led to various challenges regarding construction but mainly in construction logistics. Furthermore, construction logistics and its inner part together with building materials represent 61% of the construction cost. In 2010 construction per square meter was approximately 26 000 kr. In 2020, the cost is at 37 000 SEK/m2. Sweden also has the highest construction costs in Europe. Therefore, the biggest challenge is to reduce the cost by streamlining construction logistics. The purpose of this study is to investigate the biggest challenges that exist in construction logistics caused mainly by the Swedish economy and environmental policies. The goal is to identify the main challenges in construction logistics and what the potential measure can be applied to further reduce construction costs. The first question is what are the main challenges that construction logistics has today caused by economics and environmental policy? The second question is what measures there for these challenges are. To answer the questions, the study needs to apply a scientific research method to ensure that all data and information collected is objective. Furthermore, the study chooses a quantitative research method due to interests in statistics, generalizable and quantifiable results. In order to fulfill the purpose of the study, the quantitative method is considered the most suitable for drawing appropriate conclusions and forming better perception of reality. The results of the information obtained, and graphs/ figures indicate that fuel prices have increased, and this means higher logistical costs for the construction industry. This, in combination with stricter requirements by the state, the form of reduction obligations and net zero emissions by 2045 has created a more difficult environment to adapt to. Combination of Covid-19 and Russia's invasion of Ukraine has created an even more difficult environment. Possible measures are applying LCC and LCA to tackle the environmental policies. Economically, the suitable measure is to apply VSM to guarantee a more stable economy for the construction industry. Another measure that combines both environmental but also economic aspects is the application of BIM. Sweden is in great need of new housing and infrastructure renovations. However, taking into account the new environmental policies and economic obstacles, meeting the needs becomes more difficult. Reducing construction logistics prices, especially in transport, is a growing challenge as the state has been clear that fuel prices will most likely be the same in the future. Current situation suggests that the majority of all challenges would actually not exist from the outset. Carelessness in the form of re-tracking fees, traditional working methods, and minimal interest in innovation have been the characteristics of the construction industry for a long period. Furthermore, all these “not so big problems” have been built up and caused a “snowball effect” on the industry itself and also Sweden in general. Despite this, there are still options for at least prevention for future generations. 

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  • 42.
    Al-Dabbas, Khaled
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Analysis of GHG emissions reduction from road transport: a case study of the German passenger vehicles2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Transportation and energy play an essential role in modern society. Since the Industrial Revolution, fossil fuels have enabled great advancements in human society. Within this process, Internal Combustion Engines Vehicles (ICEVs) played a significant role in guaranteeing reliable and affordable long-distance transportation. However, the subsequent increase of the Motorized Private Transport resulted in undesired effects such as pollution. One instrument in reducing the Greenhouse Gas (GHG) emissions of the transport sector is to shift from the conventional ICEVs toward zero local emission vehicles. Electric Vehicles (EVs) are being promoted worldwide as a suitable powertrain technology that could replace the ICEVs. However, unless combined with electricity from renewable generation technologies the EVs will not effectively reduce GHG emissions. Through the simulation of future transport and energy sector scenarios in Germany, the GHG emission reductions have been analyzed. Techno-economic and environmental characteristics for several powertrain technologies under several vehicles charging strategies are evaluated. The thesis explores the impact of charging EVs on the electrical grid. The result show that EVs using smart charging strategies that support Vehicle-to-grid (V2G) are capable of fulfilling mobility needs of users while providing substantial flexibility to the electrical grid. Such flexibility can facilitate the future expansion of non-dispatchable Renewable Energy Sources (RES).

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    Analysis of GHG emissions reduction from road transport: a case study of the German passenger vehicles
  • 43.
    Aldén, Anna
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Odebo, Stina
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    The use of ground equipment at airports2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    För att flygplatser ska kunna ha så hög kapacitet som möjligt krävs effektivisering av alla delar av flygplatsverksamheten. Denna studie har identifierat problem och utvecklingsområden av användningen av markutrustning på flygplatser. I studien har det även analyserats effektiviseringsmöjligheter. Några exempel på problem och utvecklingsområden som funnits är att utrustningen är utspridd på flygplatsen och att det finns för mycket utrustning. Ett av lösningsförslagen som föreslås i rapporten är att en tredjepartsaktör äger all markutrustning på flygplatsen och sedan bedriver uthyrning av utrustningen till användarna.

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  • 44.
    Al-Egli, Asawar
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Al-Egli, Fadwa
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Kostnadsanalys och identifiering av logistikprocesser2018Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Majoriteten av företagen runt om i världen arbetar ständigt med att förbättra sin logistik. Detta eftersom om logistiken fungerar på ett bra sätt ger det upphov till ett bra flyt igenom hela processen samt bra produktresultat. Logistiken som används i dagsläget av olika byggföretag har i princip liknande grunder. Beroende på vad som skall göras kan processen skilja sig åt. Inom företaget NCC kan man hitta olika logistikprocesser som bygger på liknande förutsättningar. Varav en av logistikprocesserna ligger hos verksamheten Addera byggkoncept som arbetar utifrån ett industrialiserat koncept för renovering/stambyte av badrum i miljonprogrammets bostäder, med en mer standardiserad arbetsgång än ordinarie byggverksamhet. Denna specialanpassade logistikprocess kommer i denna studie jämföras med en mer traditionell logistikprocess för renovering/stambyte av badrum

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    Kostnadsanalys och identifiering av logistikprocesser
  • 45.
    Alfredsson, Nina
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Angvarson, Josefin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    An analysis of the robustness of SAS crew schedules2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Scandinavian Airlines (SAS) är nordens största flygbolag och har en besättning på 5 000 personer med baser i Danmark, Norge och Sverige. SAS besättningsscheman för kabinpersonal med bas Stockholm samt piloter med samma bas och kvalifikationer för flygplanstypen Boeing 737 har analyserats. Genomförda förändringar efter att scheman publicerats under 2013 och 2014 har kartlagts. Förändringarna har utretts för att fastställa hur stor andel av ett schema som genomförs som planerat. Vidare har ett mätetal som även tar hänsyn till antalet ändringar som sker från planerad ledighet och sjukdom till någon form av produktion tagits fram, mätetalet kallas förändringskvot. Andelen avvecklat enligt plan och förändringskvoten är beräknade per produktionsdag. Mätetalens resultat är relativt jämna för 2013 och 2014. År 2013 avvecklades i genomsnitt 75 % av panerade produktionsdagar och förändringskvoten utgjorde i genomsnitt 30 %. Motsvarande siffror för år 2014 var 77 % och 29 %.

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  • 46.
    al-Haji, Ghazwan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Integrated system for monitoring road safety performance in cities2014In: Urban street design & planning / [ed] Pratelli, A, WIT Press, 2014, p. 105-114Chapter in book (Refereed)
    Abstract [en]

    A strong monitoring system of road safety in a city is necessary to ensure that the strategies implemented will meet stated targets at city and national levels. Although road safety performance is a result of many key indicators, only a few of these indicators are generally considered in monitoring the performance of road safety in a city and in comparison to other cities. A number of monitoring systems are already being developed and used in road safety and they range from relatively simple models to highly complex ones depending on the number of indicators involved, details of data and complexity of methods used in calculations and analysis. In road safety, there are three main types of monitoring that are generally used, which are: Process Monitoring, Outcome Monitoring and Target Monitoring. The aim of this paper is to provide the importance and usefulness of having a fourth type of monitoring, so-called Integrated Monitoring, that links process, outcome and targets together. The paper also provides a conceptual overview, and illustrations that are used in the construction of the integrated monitoring system.

  • 47.
    al-Haji, Ghazwan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Integrated system for monitoring road safety performance in cities2011In: WIT Transactions on the Built Environment: vol 116, 2011, Vol. 116, p. 475-484Conference paper (Refereed)
    Abstract [en]

    A strong monitoring system of road safety in a city is necessary to ensure that the strategies implemented will meet stated targets at city and national levels. Although road safety performance is a result of many key indicators, only a few of these indicators are generally considered in monitoring the performance of road safety in a city and in comparison to other cities. A number of monitoring systems are already being developed and used in road safety and they range from relatively simple models to highly complex ones depending on the number of indicators involved, details of data and complexity of methods used in calculations and analysis. In road safety, there are three main types of monitoring that are generally used, which are: Process Monitoring, Outcome Monitoring and Target Monitoring. The aim of this paper is to provide the importance and usefulness of having a fourth type of monitoring, so-called Integrated Monitoring, that links process, outcome and targets together. The paper also provides a conceptual overview, and illustrations that are used in the construction of the integrated monitoring system. © 2011 WIT Press.

  • 48.
    Alho, Yasser
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Usef Eillas, Rostam
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Learning time for graduated project manager2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Byggbranschen står idag inför stora utmaningar gällande rekrytering av erfarna projektledare. Företagen har upplevt svårigheter med att hitta erfarna projektledare, detta beror på att det saknas nästan två generationer av projektledare samt att många går i pension. En lösning till problemet är att anställa nyexaminerade projektledare för att fylla luckan. Problemet med nyutexaminerade är att de saknar erfarenhet när de kommer ut i arbetslivet. Det är en utmaning för konsultföretagen, eftersom inlärningstiden för att bli projektledare vanligtvis är långa perioder.

    Syftet med denna studie är att förtydliga inlärningstiden för de nyutexaminerade projektledare samt att ge organisationen ett underlag för att de ska kunna se vad de bör skapa för förutsättningar och metoder. Huvudfrågorna som behandlas i vår studie är ”Vad innebär det att vara projektledare?” och ”Vad krävs för att man skall gå från att vara en nyutexaminerade byggingenjör till att bli projektledare?”

    Undersökningen är en kvalitativ studie som genomförts på WSP Management Östergötland. Den empiriska datainsamlingen har skett via personliga intervjuer med elva respondenter fördelade på Norrköping och Linköping kontoren.

    Studien visar på att vara projektledare kan variera mycket beroende på hur man väljer att tolka det, men inom byggbranschen handlar det om att leverera en produkt eller ett resultat till en begränsad budget och till en bestämd tid. Som projektledare är man beställarens ”högra hand” och ska uppfylla kundens önskemål i projektet. För att detta ska gå ihop krävs ständig kommunikation så att man förstår varandra och undviker missförstånd.

    Med utgångspunkt från undersökningen har vi även konstaterat att det som krävs för att man ska gå från att vara nyexaminerad byggingenjör till att bli projektledare inom området management, är rätt metod, rätt organisatoriska- och individuella förutsättningar samt att man övervinner krav och hinder som ställs från beställarsidan.

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    Learning time for graduated project manager
  • 49.
    Ali, Zakariya
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Qya, Josef
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Impact of production strategies on inventory management - A case study at a Paper Mill2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Kundundersökningar har visat att det undersökta pappersbruket bör förbättra sina leveransledtider. En lösning för detta anses vara en förändring av nuvarande produktionsstrategi. Den nuvarande produktionsstrategin är kundorderproduktion och de alternativa strategierna som kommer att undersökas under studien är lagerorderproduktion och hybridsystem. Syftet med studien är att undersöka, jämföra och analysera olika produktionsstrategier (lagerorderproduktion, kundorderproduktion och hybridsystem) samt att utvärdera deras inverkan på lagerstyrningen. För att uppnå syftet har studien baserats på tre frågeställningar: Vilka för- och nackdelar har produktionsstrategierna på färdigvarulagret samt vilka nyckeltal behöver identifieras? Vilka problem gällande produktion- och lagerstyrning stöter en produktionsplanerare i ett pappersbruk på? Vilken påverkan har produktionsstrategierna på färdigvarulagret hos det undersökta pappersbruket utifrån identifierade nyckeltal.

    Frågeställningarna besvarades genom att utföra en litteraturstudie om olika produktionsstrategier och lagerstyrning. Med hjälp av litteraturstudien har lämpliga nyckeltal identifierats för att analysera inverkan på lagerstyrning. Utöver litteraturstudien har intervjuer utförts för att skapa en bredare förståelse kring hur det undersökta pappersbruket i helhet ser på produktionsstrategier och dess inverkan på lagerstyrning. Slutligen utfördes en deskriptiv analys för att beräkna de identifierade nyckeltalen.

    Resultatet från första frågeställningen visade att olika produktionsstrategier kan bidra med olika för- och nackdelar. Dessutom anses en fördel vara en bidragande faktor till en nackdel, exempelvis för hybridsystem kan en förbättring av leveranstider medföra till problem med lagerfyllning. Det är viktigt att även ta hänsyn till hur marknaden ser ut och vilka faktorer som kan påverka samt vad kunderna efterfrågar. Resultatet från andra frågeställningen presenterade tre sammanfattande problem från de utförda intervjuerna om nuvarande produktionsstrategi och lagerstyrning. När det gäller valet av produktionsstrategi ansåg majoriteten av intervjupersonerna att produktionsstrategin hybridsystem har bäst inverkan på lagerstyrningen endast om ett antal villkor uppfylls. Villkoren är att företaget arbetar med stora volymer, har många kunder och erhåller en hög efterfrågan på standardprodukter. För frågeställning tre visade sig att produkt A hade lägst lagerföringskostnad medan produkt C hade högst lagerföringskostnad. För nyckeltalet genomloppstid visade sig att produkt C tog kortast tid och produkt B istället tog längst tid. När det gäller lägsta lagernivå finns det inga bestämda lagernivåer eller beställningspunkt som det undersökta pappersbruket förhåller sig till under produktion mot kundorder. Det resulterar till att den lägsta lagernivån är lika med noll. Om företaget producerar mot lagerorder kommer lägsta lagernivå vara 14 800 ton/år för produkt A, 20 891 ton/år för produkt B och 23 161 ton/år för produkt C. Däremot för ett hybridsystem måste företaget ta hänsyn till genomloppstiden eftersom det påverkar valet av lägsta lagernivå. Produkter med en längre genomloppstid erhåller en lägsta lagernivå nära till den förväntade producerade volymen. Produkter med kortare genomloppstid kan därmed produceras utan att begränsa produktion av resterande produkter därför kan de lagras i lägre volymer.

    Slutsatsen av studien är att företaget bör ändra produktionsstrategi till ett hybridssystem med hänsyn till det presenetrade resultatet och en ständig analys av marknaden. 

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  • 50. Order onlineBuy this publication >>
    Alkusaibati, Wael
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Digitalized Co-production of Emergency Response: Using Volunteers as First Responders2024Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Contemporary global challenges like global warming, rapid urban development, and the current unstable security situation, lead to an increase in large-scale crises (e.g., forest fires) alongside frequent smaller emergencies (e.g., house fires and traffic accidents). The increase in emergencies strains professional response organizations, necessitating additional resources. Civilian volunteers are therefore increasingly being integrated into the response system. The development is mediated by information and communication technologies (ICTs) which enable communication between professional responders (e.g., the municipal rescue services, the emergency medical services, the Public Swedish Answering Point) and citizens. While many studies focus on spontaneous volunteer activities emerging on social media, fewer examine organized volunteerism initiatives at the local emergency response level. Over a decade ago, a municipal rescue service in northern Sweden established an initiative recruiting volunteers as first responders and equipping them with basic response tools. The volunteers undergo training in tasks such as cardiopulmonary resuscitation (CPR) and fire extinguishing. They are dispatched to predefined response tasks using simple ICT applications like SMS lists or mobile apps. This initiative has expanded to other areas due to perceived benefits such as shorter response times and reduced casualties and material damage. The phenomenon can be labelled as an emerging form of ICT-enabled or digitalized co-production of public services. However, previous research indicates a research gap in understanding, describing, and defining this type of co-production. The overall aim of the thesis is to describe how these ICT-enabled initiatives emerge and develop over time and identify the related effects on the response system. This is expected to provide recommendations on how they can be developed and supported. This aim is divided into three specific objectives, where each has been addressed through a research paper: 1- identifying how the existing literature describes ICT-enabled/digitalized volunteerism in large- and small-scale emergencies, 2- identifying how these initiatives emerge and operate, and can be maintained in small-scale emergencies, introducing more systematized knowledge on this concept, 3- initially evaluating the contributions of volunteers in the initiatives. Leaning on a case study approach inspired by action research, a combination of data collection methods has been adopted, e.g., a literature review, interviews, and incident reports filled out by volunteers. For the data analysis, the theoretical lens of ICT-enabled/digitalized co-production of public services has been applied. The first paper is a literature review study that examines digitally enabled volunteering activities in crises and small-scale emergencies. It highlights the prevalence of studies on volunteers using social media for crowdsourcing in crises, often termed digitalized volunteerism which entails virtual and, or physical contributions by volunteers to the response efforts. In contrast, fewer studies focus on volunteers' role in local small-scale emergencies, labelled as "hybrid" ICT-enabled or digitalized coproduction. The term hybrid here refers to the loose affiliation of the volunteers where they collaborate with the rescue services but are not officially associated through binding contracts. Hence, they are in between spontaneous and organized volunteerism. Both volunteering modes support professional response systems and display similar needs for steering, financial support, coordination, and integration of ICT artifacts. However, crises require increased coordination to manage uncertainties, risks, and data overload effectively. The second paper presents three models describing the emergence of hybrid digitalized co-production initiatives in urban and rural areas, as defined in Paper 1, along with how national authorities can support them. These models i.e., Rural, Urban, and National consist of three phases: Recruitment, Response, and Maintenance. Each model exhibits distinct characteristics. In rural areas for example, there is a need for more regular training due to low alerting frequency, and the possibility of using simple dispatch ICTs as cost-effective solutions. Conversely, urban areas have more alerts, necessitating more advanced ICTs, with less emphasis on regular training compared to rural areas. At the macro-level, the national model highlights roles that national actors can play such as facilitating a joint Application Programming Interface (API), joint insurance solutions, and an ICT system that can register incoming and active volunteers. The third paper is an initial evaluation of these initiatives at emergency sites, focusing on ICT-enabled dispatch, estimated response times, tasks performed, and collaboration with professionals, to assess the effects of using volunteers. This approach contrasts with previous studies that took an overall perspective and only used qualitative data. A total of 53 incident reports were collected from volunteers, revealing that volunteers arrived before professionals in twothirds of incidents, contributing to an average gain of 5 minutes. Additionally, volunteers performed a broader range of tasks than previously described, and often continued collaboration with professionals on-site, despite the initial expectation of handing over tasks upon the arrival of professional response actors. Also, comparing this data with the rural model from Paper 2, similarities and differences emerged. For instance, there was a higher number of alerts, and the basic ICTs used for dispatch were deemed insufficient, contrary to the model's perception. The thesis’ scientific contribution is a clearer conception of digitalized co-production of, above all, local emergency response as an emerging phenomenon. In the three papers, the ICT dispatch was identified as central and needs further development to enhance this co-production form. The thesis also sheds light on the need to integrate the initiatives into the official governmental frameworks. Furthermore, the thesis provides a primary understanding of how the concept works on the ground and provides an initial evaluation of the effects. In the practical field, the thesis offers insights into the importance of volunteers as additional resources to the official response systems, highlights challenges, hindrances, and enablers, and suggests potential solutions and improvements. Future work will include a further collection of incident reports for more reliable assessments and complementary interviews with volunteers. Also, the potential role of volunteers in larger crises, for example, as part of civil preparedness, will be further explored.

    List of papers
    1. Digitalized Co-production and Volunteerism in Emergency Response: a Literature Review
    Open this publication in new window or tab >>Digitalized Co-production and Volunteerism in Emergency Response: a Literature Review
    2023 (English)In: Proceedings of the 20th International ISCRAM Conference / [ed] Jaziar Radianti; Ioannis Dokas; Nicolas Lalone; Deepak Khazanchi, Information Systems for Crisis Response and Management, ISCRAM , 2023, p. 738-750Conference paper, Published paper (Refereed)
    Abstract [en]

    ICT-enabled or digitalized co-production of public services has become increasingly relevant to emergency response and crisis management. This study provides a literature review on this phenomenon, exploring both large-scale crises and frequent emergencies. We found that research in the domain is scarce and focuses mainly on the phenomenon in terms of digital volunteerism. In large-scale crises, they mostly refer to spontaneous forms of volunteering, and in smaller emergencies, to more organized volunteers that collaborate with a response organization over time. Similarities to digitalized co-production in the public sector generally include financial, administrative, ICT, and demographic factors. Differences include, e.g., aspects of coordination, support, and processing by formal actors. We argue that there are benefits of adding a theoretical co-production perspective to digital volunteerism in emergency response and that our literature review can guide future research on models and (the double) use of volunteers in both kinds of emergencies.   

    Place, publisher, year, edition, pages
    Information Systems for Crisis Response and Management, ISCRAM, 2023
    Series
    ISCRAM International Conference on Information Systems, E-ISSN 2411-3387
    Keywords
    Digital, co-production, volunteers, emergency response, crisis response
    National Category
    Information Systems, Social aspects Human Aspects of ICT
    Identifiers
    urn:nbn:se:liu:diva-197659 (URN)979-8-218-21749-5 (ISBN)
    Conference
    20th Annual Global Conference on Information Systems for Crisis Response and Management (ISCRAM 2023), 28-31 May Omaha, USA
    Available from: 2023-09-06 Created: 2023-09-06 Last updated: 2024-05-03
    2. Digitalized Co-production of Emergency Response: To Make Local Initiatives National
    Open this publication in new window or tab >>Digitalized Co-production of Emergency Response: To Make Local Initiatives National
    2023 (English)In: 2023 NINTH INTERNATIONAL CONFERENCE ON EDEMOCRACY & EGOVERNMENT, ICEDEG, IEEE COMPUTER SOC , 2023, p. 37-44Conference paper, Published paper (Refereed)
    Abstract [en]

    In Sweden, digitalized co-production emergency response initiatives of a "hybrid" type emerged a decade ago. They did not involve citizens on large-scale or the public but rather targeted local efforts to recruit groups of citizens to provide first response for other citizens in frequent accidents. Substantial benefits in terms of shorter response times, saved lives, reduced human suffering and material damage, have been recognized. Nevertheless, the initiatives expansion to most municipality rescue services remains limited. Previous research has studied the co-production initiatives, focusing on digitalization/ICT as an enabler and on organizational and ICT-related hindrances. In this study, we develop three models aimed at making the local initiatives national. The presented models are adapted to rural versus urban settings and complemented with a model providing national support. Information and communication technology plays a crucial role in all models, and implications for digitalized co-production are discussed.

    Place, publisher, year, edition, pages
    IEEE COMPUTER SOC, 2023
    Series
    International Conference on eDemocracy and eGovernment ICEDEG, ISSN 2573-2005
    Keywords
    digitalization; co-production; emergency response
    National Category
    Information Systems, Social aspects
    Identifiers
    urn:nbn:se:liu:diva-196960 (URN)10.1109/ICEDEG58167.2023.10122074 (DOI)001008282100003 ()9798350324501 (ISBN)9798350324518 (ISBN)
    Conference
    9th International Conference on eDemocracy and eGovernment, (ICEDEG), Quito, ECUADOR, apr 03-05, 2023
    Note

    Funding Agencies|Swedish Civil Contingencies Agency

    Available from: 2023-08-30 Created: 2023-08-30 Last updated: 2024-05-03
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