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  • 1.
    Ahlström, Christer
    et al.
    VTI, Swedish Natl Rd and Transport Res Inst, Linkoping, Sweden.
    Anund, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. VTI, Swedish Natl Rd and Transport Res Inst, Linkoping, Sweden.
    Fors, Carina
    VTI, Swedish Natl Rd and Transport Res Inst, Linkoping, Sweden.
    Åkerstedt, Torbjorn
    Stockholm Univ, Sweden; Karolinska Inst, Sweden.
    Effects of the road environment on the development of driver sleepiness in young male drivers2018In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 112, p. 127-134Article in journal (Refereed)
    Abstract [en]

    Latent driver sleepiness may in some cases be masked by for example social interaction, stress and physical activity. This short-term modulation of sleepiness may also result from environmental factors, such as when driving in stimulating environments. The aim of this study is to compare two road environments and investigate how they affect driver sleepiness. Thirty young male drivers participated in a driving simulator experiment where they drove two scenarios: a rural environment with winding roads and low traffic density, and a suburban road with higher traffic density and a more built-up roadside environment. The driving task was essentially the same in both scenarios, i.e. to stay on the road, without much interaction with other road users. A 2 x 2 design, with the conditions rural versus suburban, and daytime (full sleep) versus night-time (sleep deprived), was used. The results show that there were only minor effects of the road environment on subjective and physiological indicators of sleepiness. In contrast, there was an increase in subjective sleepiness, longer blink durations and increased EEG alpha content, both due to time on task and to night-time driving. The two road environments differed both in terms of the demand on driver action and of visual load, and the results indicate that action demand is the more important of the two factors. The notion that driver fatigue should be countered in a more stimulating visual environment such as in the city is thus more likely due to increased task demand rather than to a richer visual scenery. This should be investigated in further studies.

  • 2.
    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.

  • 3.
    Alesand, Adam
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kostnader vid reparation av vattenläckor i Linköpings kommun2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Water is an essential resource that we today take for granted. The distribution of drinking water is done with pipes in our water distribution network. These pipes have a limited lifetime and at some point they will rupture, with a leak as a result. The leak can lead to major consequences. Some examples are: disturbance in traffics, damage to property, as well as private individuals and businesses that are without water. Another consequence is the cost itself of repairing the leak, which sometimes is the most severe consequence.

    To avoid future problems with water leaks, it is important to renew the pipe network. The planning of this renewal is called renewal planning. A method in renewal planning is so-called “risk-based renewal planning”. This method aims to find the pipes that carry the highest risk. A pipe with high risk is a pipe that has high probability of rupturing, at the same time as the consequence of a rupture is great.

    Tekniska Verken in Linköping is in charge of the water distribution network in Linköping municipality. In their renewal planning they are working on a new tool, called “Knappen”. The ambition with “Knappen” is to be able to find pipes with high risk with “just one touch of a button”. “Knappen” is a calculation based on a variety of input data on probability and consequence. One of the factors to be used in the calculation is an estimate of the repair cost that the leak causes. This study has resulted in a formula for calculating this cost.

    The formula is based on data about past leaks from 2011. The factors that the formula turned out to depend on is: in which land type the leak has occurred, how far the distance is, which repair method has to be used and also the material and dimension of the pipe.

  • 4.
    Bergman, Filip
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management.
    Olsson, Niklas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management.
    Beräkningsverktyg till strategisk planering av framtidens ledningsbundna infrastruktur: Utveckling av modell för LCC- och LCA-analyser av ledningsbunden infrastruktur2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A new law concerning sustainability reporting for companies with important functions in society means that companies need a greater focus on sustainability and thus reduce environmental impacts. To enhance sustainability and awareness of the costs and the environmental impacts from its activities, a life-cycle perspective can lead to increased knowledge and understanding.Subsurface infrastructure such as electricity, fiber, water and sewage is now a prerequisite in society. Several of the networks used today was installed in the mid-1900s, which means that they soon have reached their life expectancy. With this follows increased maintenance work and costs for the companies that manage the networks. For example, the renewal of Swedish water and sewage means an annual investment of 1.9 billion SEK, which will have to be doubled over the next 50 years. 50% of the costs to perform maintenance operations with conventional technique is due to traffic shutdown and excavation.As a result of the problems above Tekniska verken has developed an innovation for the installation of piped infrastructure, which involves systems for electrical, optical, water, sewage, waste suction and district heating, placed in a culvert. The culvert is the first of its kind and is made of plastic with concrete chambers to connect the pipes and pull out the service lines. The first place that this infra-culvert is installed in is Vallastaden in Linköping, which is exploited for Bomässan 2017.To evaluate this technology a model was developed in this thesis that can be used to calculate the life cycle costs and environmental impact of infrastructure positioned in the culvert and compare this with conventional technique. The thesis had a limited data collection that only studied the costs and the environmental impact has not been studied. The model has been developed to take into account the infrastructure stochastic nature and can calculate the average cost and standard deviations, and performing detailed sensitivity analyzes. This type of model has a number of uses for companies managing infrastructure as it gives an idea of the expected costs and can evaluate the risks associated with investments.

  • 5.
    Blane, Alison
    et al.
    Curtin Univ, Australia.
    Lee, Hoe
    Curtin Univ, Australia.
    Falkmer, Torbjörn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Curtin Univ, Australia; Jonkoping Univ, Sweden; La Trobe Univ, Australia.
    Willstrand, Tania Dukic
    Jonkoping Univ, Sweden; Swedish Natl Rd and Transport Res Inst VTI, Sweden.
    Cognitive ability as a predictor of task demand and self-rated driving performance in post-stroke drivers - Implications for self-regulation2018In: Journal of Transport and Health, ISSN 2214-1405, E-ISSN 2214-1405, Vol. 9, p. 169-179Article in journal (Refereed)
    Abstract [en]

    Driving is a highly complex task requiring multiple cognitive processes that can be adversely affected post-stroke. It is unclear how much ability post-stroke adults have to self-evaluate their driving performance. Furthermore, the impact of cognitive decline on this evaluation has not been previously investigated. The aim of this study was to investigate the perceived level of task demand involved in driving tasks, and to examine differences between perceived and observed driving performance in post-stroke drivers in comparison to a control group. A further aim of the research was to investigate the influence of cognition on self-rated driving performance. A total of 78 participants (35 post-stroke and 43 controls) were assessed using a series of cognitive tasks and were observed whilst driving. Participants were asked to rate their own driving performance and the task demand involved while driving using the NASA Task Load Index. Between group analyses were conducted to determine differences in the level of self-rated performance and task demand. Further analyses were conducted to investigate whether cognition accounted for differences in task demand or self-rated performance. Overall, the results suggested that the post-stroke drivers exhibited deficits in cognition, but they did not report increased levels of task demand when driving. Post-stroke adults also rated themselves more conservatively than the controls for on-road performance, which was associated with their reduced propensity for risk. The study suggests that cognitive deficits may influence post-stroke drivers to amend their driving behaviour, in order to bring the task demand within a manageable level. Understanding the mechanisms involved in self-rated performance and estimations of task demand can help promote accurate self-regulation practices in post-stroke drivers. Furthermore, measuring calibration may assist practitioners with assessing fitness-to-drive, as well as with tailoring driving rehabilitation.

  • 6.
    Bulusu, Vishwanath
    et al.
    Univ Calif Berkeley, CA 94720 USA.
    Sengupta, Raja
    Univ Calif Berkeley, CA 94720 USA.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Sedov, Leonid
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Cooperative and Non-Cooperative UAS Traffic Volumes2017In: 2017 INTERNATIONAL CONFERENCE ON UNMANNED AIRCRAFT SYSTEMS (ICUAS17), IEEE , 2017, p. 1673-1681Conference paper (Refereed)
    Abstract [en]

    We describe an analytical process to determine how much UAS traffic is feasible. The process is a simulator and data processing tools. The two are applied to the US San Francisco Bay Area and Norrkoping, Sweden. The amount of UAS traffic is measured in flights per day and simulated up to 200,000 flights. A UAS traffic volume is feasible if specified metrics meet operational requirements with high probability and are stable, in the sense of being below thresholds observed for monotone properties in random geometric graphs. We focus on conflict cluster size and argue for it as a fundamental safety metric worthy of extraordinary consideration.

  • 7.
    Busse, Christian
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Palmert, Frans
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Siemens Ind Turbomachinery AB, Sweden.
    Wawrzynek, Paul
    Fracture Anal Consultants Inc, NY USA.
    Sjodin, Bjorn
    Siemens Ind Turbomachinery AB, Sweden.
    Gustafsson, David
    Siemens Ind Turbomachinery AB, Sweden.
    Leidermark, Daniel
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Crystallographic crack propagation rate in single-crystal nickel-base superalloys2018In: 12TH INTERNATIONAL FATIGUE CONGRESS (FATIGUE 2018), E D P SCIENCES , 2018, Vol. 165, article id 13012Conference paper (Refereed)
    Abstract [en]

    Single-crystal nickel-base superalloys are often used in the hot sections of gas turbines due to their good mechanical properties at high temperatures such as enhanced creep resistance. However, the anisotropic material properties of these materials bring many difficulties in terms of modelling and crack growth prediction. Cracks tend to switch cracking mode from Mode I cracking to crystallographic cracking. Crystallographic crack growth is often associated with a decrease in crack propagation life compared to Mode I cracking and this must be taken into account for reliable component lifing. In this paper a method to evaluate the crystallographic crack propagation rate related to a crystallographic crack driving force parameter is presented. The crystallographic crack growth rate is determined by an evaluation of heat tints on the fracture surface of a specimen subjected to fatigue loading. The complicated crack geometry including two crystallographic crack fronts is modelled in a three dimensional finite element context. The crack driving force parameter is determined by calculating anisotropic stress intensity factors along the two crystallographic crack fronts by finite-element simulations and post-processing the data in a fracture mechanics tool that resolves the stress intensity factors on the crystallographic slip planes in the slip directions. The evaluated crack propagation rate shows a good correlation for both considered crystallographic cracks fronts.

  • 8.
    Carlsson, Arne
    et al.
    Statens väg- och transportforskningsinstitut,, VTI.
    Wiklund, Mats
    Statens väg- och transportforskningsinstitut,, VTI.
    Olstam, Johan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Tapani, Andreas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Metod för beräkning av fördröjningar på vägavsnitt utan omkörningsmöjlighet2013Report (Other academic)
    Abstract [en]

    This VTI report presents a method for calculating expected queue length and travel timedelay on one lane road sections without overtaking possibilities. The method wasdeveloped 2001 and presented in a working paper. The background for the modeldevelopment was that the Swedish Road Administration (now the Swedish TransportAdministration) planned to build so called 1+1 roads, i.e. roads with longer sectionswithout overtaking possibilities. The method developed has later on also shown to bevaluable for level of service calculations of 2+1 roads with varying share of two lanesections and for developing speed-flow relationships for the Administration’s ”Effectcalculations for road facilities”.The method uses section length, traffic flow, average speed and standard deviation asinput. The method is divided with respect to calculation of effects due to single slowrunningvehicles and effects at “normal” speed distribution. Since no data wereavailable when the model was developed, the model results were instead compared totraffic simulations with the microscopic traffic simulation model AIMSUN. The resultsshow a good correlation but the analytical model gives in general approximately 1.2 percent lower travel time delay. The differences can probably partly be explained by thestochastic parts of the simulation model. One should also remember that neither theanalytical model nor the simulation model has been calibrated and validated with realdata for this type of roads. Thus, the differences between the models do not necessaryimply that the analytical model is the one deviating from reality.

  • 9.
    Cowan, Georgia
    et al.
    Sch Occupat Therapy Social Work and Speech Pathol, Australia.
    Earl, Robyn
    Sch Occupat Therapy Social Work and Speech Pathol, Australia.
    Falkmer, Torbjörn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Girdler, Sonya
    Sch Occupat Therapy Social Work and Speech Pathol, Australia.
    Morris, Susan L.
    Curtin Univ, Australia.
    Falkmer, Marita
    Sch Occupat Therapy Social Work and Speech Pathol, Australia; Jonkoping Univ, Sweden.
    Fixation patterns of individuals with and without Autism Spectrum disorder: Do they differ in shared zones and in zebra crossings?2018In: Journal of Transport and Health, ISSN 2214-1405, E-ISSN 2214-1405, Vol. 8, p. 112-122Article in journal (Refereed)
    Abstract [en]

    Shared zones are a contemporary traffic zone that promotes equality between multiple road users and efficiently utilizes available space, while simultaneously maintaining safety and function. As this is a relatively new traffic zone, it is important to understand how pedestrians navigate a shared zone and any potential challenges this may pose to individuals with impairments. The aim of this study was to utilize eye-tracking technology to determine fixations and fixation duration on traffic relevant objects, non-traffic relevant objects, and eye contact, in 40 individuals with and without Autism Spectrum Disorder (ASD) in a shared zone and a zebra crossing. It was assumed that individuals with ASD would make less eye contact in the shared zone compared to the group of typically developing adults. A total of 3287 fixations across the shared zone and zebra crossing were analysed for areas of interest that were traffic relevant, non-traffic relevant, and eye contact, and for fixation duration. Individuals with ASD did not display any difference in terms of eye contact in the shared zone and the zebra crossing when compared to the controls. All pedestrians were more likely to look at traffic relevant objects at the zebra crossing compared to the shared zone. Individuals with ASD had an overall shorter fixation duration compared to the control group, indicating people with ASD either process information quickly, or they do not process it for long enough, although these findings require further investigation. While shared zones have many benefits for traffic movement and environmental quality, it appeared that pedestrians displayed safer road crossing behaviours at a zebra crossing than in a shared zone, indicating that more education and environmental adaptations are required to make shared zones safe for all pedestrians.

  • 10.
    Gustafsson, Marcus
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Staden som gruva: I fäders spår för framtids segrar2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Earth’s natural mineral resources have, to some extent, already been used and depleted, and the future is both uncertain and debated. No one knows for certain exactly how much metal there is left in Earth’s crust, how much we can extract or for how long the resources are going to last. Meanwhile, we have installed ores of metal in our cities, in the form of electric cables, telecom cables and district heating pipes. Many of these are of course in use, but many have also reached end of life and been disconnected, and are thus available for recycling.The purpose of this study is to clarify barriers, drivers and enablers for metal recycling of disconnected underground infrasystems within the local electricity, telecom and district heating networks in Sweden. In order to do this, ten of Sweden’s largest owners of local underground electricity networks were asked e.g. about their routines and about projects where cables were taken up. The same companies were also asked about their district heating networks. Apart from these, the study included the telecom network owner Skanova, municipalities with connections to the ten electricity network companies, metal recycling companies, contractors and authorities. Furthermore, a literature study on metal recycling was conducted.The main drivers for taking up and recycling disconnected underground infrasystems proved to be economy, conflicts of space in the ground, rules and regulations in terms of legislations, contracts or company policies, and environmental impact risks. All of these, except for conflicts of space, could also, depending on the circumstances, be barriers for recycling. One important enabler is to know the exact position of the cables or pipes and that they don’t risk being confused with other cables or pipes.Presently, cables and pipes are commonly left in the ground for some time after they have been taken out of service. When they are eventually taken up, it is often done simultaneously with other digging operations along the cable or pipe. Environmental risks, conflicts of space and rules and regulations can force the excavation of cables and pipes, while economy, with current metal prices, is more of a barrier. If recycling of underground infrasystems is to become norm, the profitability needs to increase. This can occur through increased metal prices, use of alternative excavation methods, a wider view that takes into account that increased recycling can decrease the need for primary metal resources, or perhaps through subsidization of recycled metals. Tougher legislations could force a higher recycling rate, but in order to include all involved parts and not upset anyone, it is better to let the market drive and base it all on free will.If the recycling of underground infrasystems is to increase, efforts must be made on several different levels. New methods, developed by independent entrepreneurs, could make recycling more profitable. National goals and guidelines should be presented by the Swedish EPA, to guide and direct network owners and landlords. If financial instruments are needed, these must be decided upon by the parliament. Business associations and county administrations can coordinate the work among their members and within their regions. The landlords and the network owners must then agree on what is appropriate and applicable for their specific areas.

  • 11.
    Hermelin, Brita
    et al.
    Linköping University, Department for Studies of Social Change and Culture, Centre for Municipality Studies – CKS. Linköping University, Faculty of Arts and Sciences.
    Fenton, Paul
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Ragnarsson, Terje
    Linköping University, Department for Studies of Social Change and Culture, Centre for Municipality Studies – CKS. Linköping University, Faculty of Arts and Sciences.
    Infrastrukturinvesteringar, kommunal planering och hållbar samhällsutveckling – erfarenheter från BanaVäg Motala-Mjölby2015Report (Other academic)
    Abstract [sv]

    Studien ”Infrastrukturinvesteringar, kommunal planering och hållbar samhällsutveckling” som presenteras i denna rapport riktar intresset mot mindre kommuners och orters förutsättningar att ta del av stora infrastrukturprojekt. 

    Studien har undersökt hur kommunerna Motala och Mjölby genom planeringsinsatser, initiativ och samarbeten har verkat för att stärka nyttan och effekterna av tillgängligheten till ny- och ombyggd fysisk infrastruktur i samband med genomförandet av BanaVäg Motala-Mjölby. Det empiriska underlaget utgörs av kommunala planeringsdokument och intervjuer med representanter för kommunerna och andra lokala organisationer.

    BanaVäg Motala-Mjölby genomfördes 2008-2013 och innebar ny sträckning av Riksväg 50 mellan Motala och Mjölby, ny genomfart i Motala med ny bro över Motalaviken samt utbyggnad av järnvägen till dubbelspår mellan Motala och Mjölby. Motala och Mjölby kommuner tillhör Östergötlands län och ligger i omlandet för Linköping som utgör ett viktigt centrum för den regionala arbetsmarknadsregionen. Mjölby har en befolkning på knappt 30 000 invånare, medan Motalas befolkning uppgår till knappt 43 000 invånare. Studien har geografisk fokus till Motala och Mjölby centralorter och till Skänninge tätort.

    Kommunernas planering för att stärka nyttan av  infrastruktursatsningen sker integrerat med olika planeringsområden och avgränsningen av vilka planeringsinsatser som berörts i studien har diskuteras med kommunerna. Studien visar att planerna för tätorterna Motala, Mjölby och Skänninge delar en rad utvecklingsmål som exempelvis förtätning och funktionsintegrering i stadskärnan, att bygga bostäder i stationsnära områden, att förlägga störande verksamheter i nära anslutning till riksvägar och motorväg och att värna centrumlokaliserad detaljhandel genom att vara restriktiv till sådan lokalisering i externa lägen. Båda kommunernas planering präglas av ambitionen att förstärka respektive kommuns centralort. Svårförenade intressen och utmaningar diskuteras i planeringsdokumenten; exempelvis avvägningen mellan strandskydd och exploatering, samt bullernivåer i infrastrukturnära områden. Båda Motala och Mjölby kommuner framhåller betydelsen av visionsarbete och att utveckla sina platsvarumärken. Det har samband med att lokal utveckling sker genom att olika aktörer samarbetar och visioner kan vara ett stöd till att utveckla gemensamma mål och samverkansinsatser. Samverkan med byggbolag, företag, detaljhandel, organisationer och lokalbefolkningen är en förutsättning för att planeringsmålen ska kunna omsättas i praktiken.

    Många av de som intervjuades för studien instämmer med den breda uppfattningen att infrastruktur har djupgående effekter för lokal utveckling. Flera av respondenterna uttrycker dessutom förvåning över att effekterna av BanaVäg Motala-Mjölby har uppstått väldigt snabbt och till och med innan den nya infrastrukturen var byggd. Effekterna av infrastruktursatsningen blir olika för de tätorter som står i fokus för studien. Mjölby tätort arbetar i hög grad med att fortsätta att utnyttja en god infrastruktur man haft tillgång till sedan en tid tillbaka. Motala och Skänninge, däremot, har hamnat i radikalt förbättrade infrastrukturlägen via BanaVäg-projektet. Alla studerade orter rapporterar stark efterfrågan på pendeltåget.

    Mer generella slutsatser av studien formuleras som tre lärdomar och råd. För det första är det en stor fördel att inleda planeringsinsatser för fysisk och för strategisk planering tidigt, även om inte förutsättningarna för kommande infrastrukturutbyggnad är kända i detalj. Med utgångspunkt i att fysisk planering är nödvändigt men inte tillräckligt för att stödja lokal utveckling betonar lärdom nummer två betydelsen av strategisk planering och samverkan över samhällssektorer. Lärdom nummer tre handlar om behovet av att förstärka insatser för hållbara transporter. Generellt sett är detta inte så tydligt utvecklat samtidigt som det är viktigt att notera att det är en närvarande fråga i kommunernas planeringsdokument och respondenternas reflektioner.

  • 12.
    Johansson, Fredrik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Microscopic Simulation of Pedestrian Traffic2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There has recently been a renewed interest in planning for pedestrian traffic, primarily in connection to public transport interchange stations, since these are important for public transport to constitute an attractive alternative to car usage. This thesis concerns microscopic simulation of pedestrian traffic, which is a promising tool for analyzing and predicting the traffic situation in a given pedestrian facility; particularly powerful when the traffic is congested. Important applications of microscopic simulation include comparison of possible infrastructure designs such as proposed interchange stations, and evaluations of various traffic management solutions, for example information systems.

    The purpose of this thesis is to advance the capabilities of pedestrian microsimulation toward a level at which it can be reliably applied for quantitative analysis by practitioners in the field. The work is based on an established microscopic model of pedestrian dynamics, the Social Force Model (sfm), and the advances are made in a number of different areas.

    To be able to evaluate and compare simulated traffic situations suitable performance measures are needed. A set of local performance measures are proposed that quantifies the local delay rate density and estimates the discomfort perceived by the pedestrians.

    The sfm is extended to include waiting pedestrians through the introduction of a waiting model, demonstrated to be stable and free from oscillations. The inclusion of waiting pedestrians in the model is critical for accurate modelling of public transport interchange stations, where large groups of waiting pedestrians may hinder passing pedestrians if the design of the station is poor.

    The relaxation time of the adaptation to the preferred velocity is an important parameter in force based models of pedestrian traffic since it affects several behaviors of the simulated pedestrians, two of which are linear acceleration and turning movements. A comparison of observations of accelerating pedestrians reported in the literature and new observations of turning pedestrians indicates that no value of the relaxation time can give model behavior consistent with both sets of observations. This indicates that modifications of the model is needed to accurately reproduce the observed behavior.

    An important input to simulations is the preferred speed of the simulated pedestrians. The common assumption that the preferred speed distribution at a location does not vary during the day is tested through observations of pedestrian traffic at Stockholm Central Station. The results demonstrate that the preferred speeds are lower in the afternoon than in the morning, implying that the preferred speed should be treated as a source of uncertainty when applying pedestrian microsimulation.

    Finally, a sensitivity analysis of a simulation of the lower hall of Stockholm Central Station is performed to find the most important sources of uncertainty in the model predictions, given the available data. The results indicate that the uncertainty related to calibration is the largest of the considered potential error sources.

    List of papers
    1. Local performance measures of pedestrian traffic
    Open this publication in new window or tab >>Local performance measures of pedestrian traffic
    2014 (English)In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 6, no 1-2, p. 159-183Article in journal (Refereed) Published
    Abstract [en]

    Efficient interchange stations, where travelers are changing lines and/or travel modes, are essential for the functionality of the whole public transport system. By studying pedestrian movements, the level of service and effectiveness imposed by the design of the interchange station can be evaluated. We address the problem by microsimulation, where a social force model is used for the phenomenological description of pedestrian interactions. The contribution of this paper is the proposal of measures describing the density, delay, acceleration and discomfort for pedestrian flows. Simulation experiments are performed for the movements in two canonical pedestrian areas, a corridor and a corridor intersection. Clearly, each of the four measures gives a description for how pedestrians impede each other, and hence for the efficiency at the facility. There is, however, different information provided by each measure, and we conclude that they all are well-motivated for quantifying the level of service in a pedestrian flow. We also illustrate the outcome for a railway platform, with two trains arriving in parallel.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2014
    Keywords
    Interchange stations, Microsimulation, Pedestrians, Social force model
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-109045 (URN)10.1007/s12469-013-0081-9 (DOI)
    Available from: 2014-08-04 Created: 2014-08-04 Last updated: 2018-08-23Bibliographically approved
    2. Waiting pedestrians in the social force model
    Open this publication in new window or tab >>Waiting pedestrians in the social force model
    2015 (English)In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 419, p. 95-107Article in journal (Refereed) Published
    Abstract [en]

    Microscopic simulation of pedestrian traffic is an important and increasingly popular method to evaluate the performance of existing or proposed infrastructure. The social force model is a common model in simulations, describing the dynamics of pedestrian crowds given the goals of the simulated pedestrians encoded as their preferred velocities. The main focus of the literature has so far been how to choose the preferred velocities to produce realistic dynamic route choices for pedestrians moving through congested infrastructure. However, limited attention has been given the problem of choosing the preferred velocity to produce other behaviors, such as waiting, commonly occurring at, e.g., public transport interchange stations. We hypothesize that: (1) the inclusion of waiting pedestrians in a simulated scenario will significantly affect the level of service for passing pedestrians, and (2) the details of the waiting model affect the predicted level of service, that is, it is important to choose an appropriate model of waiting. We show that the treatment of waiting pedestrians have a significant impact on simulations of pedestrian traffic. We do this by introducing a series of extensions to the social force model to produce waiting behavior, and provide predictions of the model extensions that highlight their differences. We also present a sensitivity analysis and provide sufficient criteria for stability. (C) 2014 Elsevier B.V. All rights reserved.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Social force model; Waiting pedestrians; Microscopic simulation
    National Category
    Civil Engineering
    Identifiers
    urn:nbn:se:liu:diva-113715 (URN)10.1016/j.physa.2014.10.003 (DOI)000347017300012 ()
    Note

    Funding Agencies|Swedish Transport Administration [TRV 2013/13329]

    Available from: 2015-01-30 Created: 2015-01-29 Last updated: 2018-08-23
    3. The Many Roles of the Relaxation time Parameter in Force based Models of Pedestrian Dynamics
    Open this publication in new window or tab >>The Many Roles of the Relaxation time Parameter in Force based Models of Pedestrian Dynamics
    2014 (English)In: Transportation Research Procedia, Elsevier, 2014, Vol. 2, p. 300-308Conference paper, Published paper (Other academic)
    Abstract [en]

    In force based models of pedestrian traffic, the relaxation time, τ, is related to the time it takes a pedestrian to adapt its motion to its preferences. An example of this is linear acceleration, but τ is also connected to how the agent adjusts to spatial variations in its preferred velocity, and affects evasive maneuvers. These many roles of τ may be a problem when calibrating force based models.

    We compare linear acceleration, to new data on, and simulations of, turning movements. The results indicate that the models predict drifting of a magnitude that is not supported by the data.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    pedestrian simulation; force based models; calibration; relaxation time; social force model
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-119121 (URN)10.1016/j.trpro.2014.09.057 (DOI)
    Conference
    The Conference on Pedestrian and Evacuation Dynamics 2014 (PED 2014)
    Available from: 2015-06-09 Created: 2015-06-09 Last updated: 2016-12-20
  • 13.
    Kircher, Katja
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences. The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Ahlstrom, Christer
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Evaluation of methods for the assessment of attention while driving2018In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 114, p. 40-47Article in journal (Refereed)
    Abstract [en]

    The ability to assess the current attentional state of the driver is important for many aspects of driving, not least in the field of partial automation for transfer of control between vehicle and driver. Knowledge about the drivers attentional state is also necessary for the assessment of the effects of additional tasks on attention. The objective of this paper is to evaluate different methods that can be used to assess attention, first theoretically, and then empirically in a controlled field study and in the laboratory. Six driving instructors participated in all experimental conditions of the study, delivering within subjects data for all tested methods. Additional participants were recruited for some of the conditions. The test route consisted of 14 km of motorway with low to moderate traffic, which was driven three times per participant per condition. The on-road conditions were: baseline, driving with eye tracking and self paced visual occlusion, and driving while thinking aloud. The laboratory conditions were: Describing how attention should be distributed on a motorway, and thinking aloud while watching a video from the baseline drive. The results show that visual occlusion, especially in combination with eye tracking, was appropriate for assessing spare capacity. The think aloud protocol was appropriate to gain insight about the drivers actual mental representation of the situation at hand. Expert judgement in the laboratory was not reliable for the assessment of drivers attentional distribution in traffic. Across all assessment techniques, it is evident that meaningful assessment of attention in a dynamic traffic situation can only be achieved when the infrastructure layout, surrounding road users, and intended manoeuvres are taken into account. This requires advanced instrumentation of the vehicle, and subsequent data reduction, analysis and interpretation are demanding. In conclusion, driver attention assessment in real traffic is a complex task, but a combination of visual occlusion, eye tracking and thinking aloud is a promising combination of methods to come further on the way. (C) 2017 Elsevier Ltd. All rights reserved.

  • 14.
    Kircher, Katja
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences. Swedish Natl Rd and Transport Res Inst VTI, Linkoping, Sweden.
    Ahlstrom, Christer
    Swedish Natl Rd and Transport Res Inst VTI, Linkoping, Sweden.
    Nylin, Magnus
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Mengist, Alachew
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Tactical steering behaviour under irrevocable visual occlusion2018In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 55, p. 67-77Article in journal (Refereed)
    Abstract [en]

    Objective: To investigate the extent of a drivers mental model with irrevocable visual occlusion and analysing the distance to crash. Background: Drivers have a mental model of the immediate surroundings which allows them to predict their own as well as others travel paths. To navigate safely through traffic, this mental model has to be updated frequently to remain valid. In between information sampling events, the mental model will become outdated over time, as the traffic system is dynamic. Method: A simulator study with 22 participants was conducted to investigate the information decay in the mental model. This was implemented by extending visual occlusion until the driver collided with another vehicle or ran off the road, thus providing an estimate of how long it takes until the mental model becomes obsolete. Results: An analysis of variance with the factors curve direction, curve radius and traffic showed that curve radius did not influence the distance to crash. Without traffic, drivers veered off the road sooner in right curves. Adding traffic eliminated this difference. Traffic ahead led to a shortened distance to crash. Compared to a tangential travel path from the current lateral position at the time of the occlusion, drivers crashed on average 2.6 times later than they would have, had they not had any mental model of the situation. Conclusions: The drivers mental representation of the future situation seems to include information on how to act, to alleviate deviations in yaw angle, including and considering the presence of other road users. (C) 2018 Elsevier Ltd. All rights reserved.

  • 15.
    Kircher, Katja
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences. Swedish Natl Rd and Transport Res Inst VTI, S-58195 Linkoping, Sweden.
    Ihlstrom, Jonas
    Swedish Natl Rd and Transport Res Inst VTI, S-58195 Linkoping, Sweden.
    Nygårdhs, Sara
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Arts and Sciences. Swedish Natl Rd and Transport Res Inst VTI, S-58195 Linkoping, Sweden.
    Ahlstrom, Christer
    Swedish Natl Rd and Transport Res Inst VTI, S-58195 Linkoping, Sweden.
    Cyclist efficiency and its dependence on infrastructure and usual speed2018In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 54, p. 148-158Article in journal (Refereed)
    Abstract [en]

    Bicyclists are a heterogeneous group, with varying abilities, traffic education and experience. While efficiency was identified as an important factor on utility bicycle trips, it might be traded for experienced safety, for example by choosing different pathways in a given situation, or by relinquishing ones right of way. In a semi-controlled study with 41 participants, a grouping was made according to self-reported riding speed in relation to other cyclists. The participants cycled twice along a 3 km inner-city route, passing four intersections with different priority rules. The cyclists were free to choose how to negotiate the intersections. Speed and the traffic surroundings were recorded via gps and cameras on the bike of the participant and of a following experimenter. For each cyclist, the base speed on undisturbed segments was determined as reference. Based on this, the efficiency in different types of intersections was computed per cyclist group. It turned out that infrastructural aspects, cyclist group and the presence and behaviour of interacting traffic influenced cyclist efficiency. Faster cyclists were delayed more when the infrastructure required a stop regardless of the traffic situation, like at a red traffic light or a stop sign. The members of the so-called comfort cyclists group were delayed the most in a roundabout with mixed traffic, where many chose to get off their bike and walk. In a society working for equality of access to the transport system, it is recommended to develop solutions that consider and accommodate the behaviours of different cyclist groups when planning bicycling infrastructure. (C) 2018 Elsevier Ltd. All rights reserved.

  • 16.
    Krook, Joakim
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Wallsten, Björn
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Syntesrapport från projektet Städer som gruvor: tio huvudpunkter2017Report (Other academic)
    Abstract [sv]

    Städer är centrala i hållbarhetsarbetet, inte minst på grund av att den urbana livsstilen är en starkt bidragande orsak till många av dagens resurs– och miljöproblem. Men städer uppvisar också möjligheter till förändring och utveckling av lösningar för en effektivare användning av resurser. Ledningsbundna infrasystem för el, tele, fjärrvärme, vatten, etc. utgör stadens tekniska ryggrad. Att upprätthålla dessa markförlagda systems funktioner bygger på ett ständigt återkommande behov av schaktarbeten, vilket förutom stora kostnader orsakar betydande miljöpåverkan och intrång i stadslivet. Dessa nätverk innehåller också stora förråd av metaller som koppar och aluminium, vilka över tiden har lagrats i alla de hundratusentals mil av kablar och rör som ligger nedgrävda under våra gator och torg. Idag sker ingen återvinning av dessa metaller utan systemdelarna lämnas i regel bara kvar i marken efter att ha tagits ur bruk.

    Vid Linköpings universitet har vi under flera år bedrivit forskning om “Städer som gruvor” tillsammans med nätägare och återvinningsföretag som Tekniska Verken i Linköping, Skanova och Stena Recycling. Projektet har finansierats av Vinnova och syftat till att ta fram kunskap om när, var och hur återvinning kan bli en del av infrasystemens förvaltning.

    Syftet med denna syntesrapport är att sammanfatta de viktigaste lärdomarna från projektet Städer som gruvor II på ett lättillgängligt sätt. Rapporten består av tio huvudpoänger. De berör allt ifrån infrasystemens resurspotential och förutsättningar för återvinning, till behov av förändringar i praktik och policy. Dessa poänger täcker givetvis inte in alla resultat från projektet utan ambitionen är snarare att peka på centrala motiv, möjligheter och utmaningar och därigenom lyfta frågan bland branschens aktörer och andra intressenter. Förhoppningen är att vi på detta sätt kan så ett frö till diskussion om förändring i riktning mot en resurseffektivare förvaltning av stadens ledningsbundna infrastruktur.

    För den som vill veta mer finns en lista på källmaterial och kontaktpersoner i slutet av rapporten.

  • 17.
    Leidermark, Daniel
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Rouse, James P.
    Univ Nottingham, England.
    Hyde, Christopher J.
    Univ Nottingham, England.
    Stekovic, Svjetlana
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Thermomechanical fatigue crack initiation in disc alloys using a damage approach2018In: 12TH INTERNATIONAL FATIGUE CONGRESS (FATIGUE 2018), E D P SCIENCES , 2018, Vol. 165, article id 19007Conference paper (Refereed)
    Abstract [en]

    A fatigue crack initiation model based on damage accumulation via a fatigue memory surface in conjunction with a plastic strain energy parameter was evaluated for thermomechanical fatigue loading in a gas turbine disc alloy. The accumulated damage in each hysteresis loop was summed up, and it was assumed that the damage at the stable state is repeated until failure occurs. Crack initiation occurs when enough fatigue damage has been obtained, and the number of cycles can thus be directly determined. The fatigue damage is highly coupled to the constitutive behaviour of the material, where the constitutive behaviour was modelled using a non-linear hardening description. Based on this, a stable state was achieved and the obtained damage could be extracted. A user-defined material subroutine was implemented, incorporating both the constitutive description and the fatigue damage accumulation. The framework was adopted in a finite element context to evaluate the thermomechanical fatigue crack initiation life of the disc alloy RR1000. From the evaluation it could be seen that a good prediction of the thermomechanical fatigue life was achieved compared to performed experiments.

  • 18.
    Lingegård, Sofia
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Integrated Product Service Offerings for Rail and Road Infrastructure: Reviewing Applicability in Sweden2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This research aims to explore and propose a more effective management of rail and road infrastructure and the possibility of a more resource-efficient road and rail infrastructure by applying business models based on performance and a life-cycle perspective.

    There is a lack of efficiency in the Swedish rail and road infrastructure industries - at the same time as the availability of the rail tracks and roads is essential. Rail and road infrastructure have long lifetimes, around 40-60 years, and during these decades regular maintenance and reconstruction are needed to ensure proper function. Large amounts of resources are required to construct the infrastructure, and the overall environmental pressure depends substantially on this.

    This research is largely based on interviews conducted with the buyer, contractors and design consultants for rail and road infrastructure in Sweden. Literature reviews have been conducted to develop the framework needed to analyze the empirical findings. This research contributes by building on theory in areas such as Integrated Product Service Offerings (IPSOs) and eco-design, and this abstract presents a brief summary of the overall conclusions.

    Several challenges for rail and road infrastructure in Sweden have been identified, such as the lack of information and knowledge transfer between different projects and actors. This is due to e.g. the use of traditional short-term contracts and conservative cooperate cultures, creating sub-optimizations in management. Increased collaboration, through e.g. partnering, seems to be a promising way to increase the information and knowledge transfer between actors by increasing trust and interaction. In this way, management would be more effective, and by involving contractors in the design phase, more efficient technical solutions could be developed and used. Additionally, increased involvement by the design consultants and an iterative information loop between design, construction and maintenance could also be beneficial. The research indicates that increased cooperation increases trust. In this way, there is a possibility to remove the detailed requirements that prevent new ways of working.

    Rail and road infrastructure have characteristics, such as the resources used and the importance of availability, that are well-suited for IPSOs. This performance-based business model with a life-cycle perspective provides incentives to optimize the use of resources and provide a holistic view for management that is lacking today for rail and road infrastructure. However, a long-term contract such as an IPSO creates uncertainties. The actors are risk-averse, which is an obstacle in the development of new business models and contract forms. Most of the risks and uncertainties identified are due to lack of experience. This implies that an implementation of IPSOs will have a steep learning curve. Additionally, risk allocation between the actors is important for effective management: too much risk for the suppliers will make them reluctant in developing new solutions, and they will use a risk premium to cover up for the risk.

    List of papers
    1. PSS Contracts for Rail and Road Infrastructure
    Open this publication in new window or tab >>PSS Contracts for Rail and Road Infrastructure
    2011 (English)In: Functional Thinking for Value Creation. Proceedings of the 3rd CIRP International Conference on Industrial Product Service Systems, Technische Universität Braunschweig, Braunschweig, Germany, May 5th-6th, 2011 / [ed] Jürgen Hesselback & Christoph Herrmann, Springer Berlin/Heidelberg, 2011, p. 291-296Conference paper, Published paper (Refereed)
    Abstract [en]

    The productivity development for rail and road infrastructure has been weak a long time; and explanation can be found in the traditional contracts used, with little room for incentives for innovation. This literature study investigates the use of the few realized PSS contracts within the rail and road infrastructure. The descriptions and the scientific reports are on a synoptic level and a majority of the reports are funded by the involved actors, showing that there is an interest for PSS contracts in the industry and indicating significant potential for further research in the area.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2011
    Keywords
    Rail infrastructure; Road Infrastructure; Literature review
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-70261 (URN)10.1007/978-3-642-19689-8_51 (DOI)978-3-642-19688-1 (ISBN)978-3-642-19689-8 (ISBN)
    Conference
    The 3rd CIRP International Conference on IPS2 2011, May 5th-6th, Braunschweig, Germany
    Available from: 2011-08-29 Created: 2011-08-29 Last updated: 2014-09-03Bibliographically approved
    2. Integrated Product Service Offerings for rail infrastructure: benefits and challenges regarding knowledge transfer and cultural change in a Swedish case
    Open this publication in new window or tab >>Integrated Product Service Offerings for rail infrastructure: benefits and challenges regarding knowledge transfer and cultural change in a Swedish case
    2015 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 98, p. 166-174Article in journal (Refereed) Published
    Abstract [en]

    The aim of this paper is to investigate potential benefits and challenges regarding knowledge transfer and cultural change from the provider and buyer perspectives when using IPSOs for Swedish rail infrastructure. Considering material use and the importance of availability of the tracks makes rail infrastructure an interesting candidate for a business model based on a life-cycle approach, which can result in a reduction in cost and environmental impact.

    The concept of the Integrated Product Service Offering (IPSO) has in several business areas proven to be a means with potential to reduce the environmental impact of products and services, increase cost efficiency and quality, and act as a driver for change. The business model, which is based on a life-cycle approach, focuses on the function instead of the initial price of the product.

    Among the main findings are the lack of information and knowledge transfer that act as a barrier for innovation, and that the buyer's conservative business culture makes it difficult to implement new types of contracts. Since IPSO contracts require improved information transfer, they could potentially stimulate innovation as well as processes for evaluation of the contracts. By involving the contractors in the design phase their knowledge could be used in a better way, creating a feedback loop from practice to design.

    The empirical part, focusing on the rail infrastructure industry in Sweden, has been collected using individual interviews and a group interview approach.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Rail infrastructure, Long-term contracts, Supplier–buyer relationships, Knowledge transfer
    National Category
    Environmental Sciences Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-109976 (URN)10.1016/j.jclepro.2014.06.039 (DOI)000356194300017 ()
    Available from: 2014-08-29 Created: 2014-08-29 Last updated: 2017-12-05Bibliographically approved
    3. Scenarios for Resource Efficient Rail Infrastructure: Applying Integrated Product Service Offerings
    Open this publication in new window or tab >>Scenarios for Resource Efficient Rail Infrastructure: Applying Integrated Product Service Offerings
    2014 (English)In: PRODUCT SERVICES SYSTEMS AND VALUE CREATION: PROCEEDINGS OF THE 6TH CIRP CONFERENCE ON INDUSTRIAL PRODUCT-SERVICE SYSTEMS, Elsevier, 2014, Vol. 16, p. 13-139Conference paper, Published paper (Refereed)
    Abstract [en]

    The rail infrastructure in Sweden, with its long lifetime, large amounts of materials used and traditional procurement, has escalating maintenance costs. What would occur if the infrastructure is instead procured as an Integrated Product Service Offering (IPSO)? This paper discusses scenarios for increased resource efficiency and more value for the money spent by applying an IPSO perspective to rail infrastructure. The best option depends on the conditions at the construction site as well as how much the availability of the tracks is valued.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Series
    Procedia CIRP, ISSN 2212-8271 ; 16
    Keywords
    Rail infrastructure, maintenance, availability, product service systems
    National Category
    Environmental Sciences
    Identifiers
    urn:nbn:se:liu:diva-109977 (URN)10.1016/j.procir.2014.06.001 (DOI)000345448900023 ()
    Conference
    6th CIRP Conference on Industrial Product-Service Systems (IPSS)
    Available from: 2014-08-29 Created: 2014-08-29 Last updated: 2015-01-08Bibliographically approved
    4. Partnering – a Way to Reach Resource-Efficient and Effective Road Infrastructure Projects through Increased Information and Knowledge Transfer?
    Open this publication in new window or tab >>Partnering – a Way to Reach Resource-Efficient and Effective Road Infrastructure Projects through Increased Information and Knowledge Transfer?
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The construction industry is behind other industries when it comes to efficiency, and partnering has been discussed as a way to increase the cooperation in and technical performance of projects. For partnering to be successful several different aspects have to be in place, among them information sharing and trust. The objective is therefore to investigate implications of partnering as a way to reach more resource-efficient and effective road infrastructure projects through increased information and knowledge transfer.

    The article investigates a road project realized using less time than estimated as well as achieving a lower total cost than budgeted. Partnering resulted in a close collaboration and increased trust among the actors, and the co-location of the actors led to the exchange of information and especially informal communication. Information was easily accessed and transferred between the actors, and the cooperation facilitated knowledge transfer between the different functions. This cut the lead times on information transfer and decision making, especially in the integrated construction and design phase, making the project more efficient. Also, solutions adapted for the site were chosen thanks to the active design approach. Instead of spending time on remaking poorly-adapted designs, time could be spent on other things, making the process more effective as well. The success of the project suggests that partnering could be a way forward in the road infrastructure industry. However, even more resource-efficient solutions could have been chosen if the project had a life-cycle perspective.

    Keywords
    Buyer-supplier collaboration, partnering, resource efficiency, road infrastructure, knowledge transfer, information transfer
    National Category
    Environmental Sciences
    Identifiers
    urn:nbn:se:liu:diva-109979 (URN)
    Available from: 2014-08-29 Created: 2014-08-29 Last updated: 2015-01-07Bibliographically approved
    5. Identification of Risks Related to Integrated Product Service Offerings of Rail Infrastructure
    Open this publication in new window or tab >>Identification of Risks Related to Integrated Product Service Offerings of Rail Infrastructure
    2014 (English)In: Through-life Engineering Services / [ed] Louis, Rajkumar Roy, Springer, 2014Chapter in book (Other academic)
    Abstract [en]

    Among construction companies in Sweden, incentives for development, increased efficiency and raised competence are low. In Sweden, construction contracts are currently used to a large extent, and have shortcomings concerning weak incentives for development of procedures. The over-detailed specifications cause major obstacles for the rail infrastructure industry in terms of technical development. There is clearly a need for change, and it is now in the strategy of the Swedish Transport Administration (STA) to get as much railway as possible for the money it spends. This includes increased productivity, level of innovation and competition, as well as a will to think more from a life-cycle perspective and increase cost efficiency. Changes in the business model is one of the strategies mentioned to reach these goals.

    Performance contracting could increase the drivers for change within the industry and thereby increase cost efficiency and quality from a life cycle perspective. This type of contracting is also known as an Integrated Product Service Offering, or IPSO, and implies that one actor has the responsibility to deliver a result and therefore has incentives to optimize the use of energy and material. An IPSO has a lifecycle perspective, and the combination of products and services can be combined into an optimized solution for the customer, as well as give the manufacturing company the possibility to have control over the product throughout its whole life-cycle. PSS provides the supplier with the opportunity to increase the value of the solution for the customer by integrating components in new ways, as well as incentives for the supplier to realize a more economical and environmental development when considering the whole lifecycle. More money spent on the construction, and thereby improved quality, could result in reduced cost for maintenance work. On the other hand, too high a cost for construction can never be motivated by future savings for the maintenance cost.

    New business models such as IPSO contracts create challenges such as uncertainty concerning forecasting costs at the bidding phase of the contract. With a business model focusing on delivering a result, a lot of the risk previously carried by the user is now assumed by the provider, and it can be difficult rededicating and controlling the risks and uncertainties. In this case the term “risk” is defined as the threat of loss from an unwanted event, to include financial, performance or timescale loss. Risk assessments, including forecasting and economic development, are very important for these long-term contracts and both the supplier side and the buyer side have to be considered. For longterm performance contracts risks caused by uncertainties arise in the bidding stage. Key uncertainties for a IPSO contract are performance, operation, training, engineering, affordability and commercial uncertainties.

    In cooperation with the STA, the DORIS (Development of integrated product service Offerings for Rail Infrastructure Systems) project investigates the potential use of IPSO contracts for rail infrastructure. So far, only one such contract has been realized; this was partly funded by private capital, and no such initiatives are currently planned. This limited experience in the industry calls for more thorough research. In line with this, the aim of this paper is to identify potential risk components when using IPSO for rail infrastructure for both the provider and buyer perspectives. Furthermore, the paper seeks to investigate how these risks can be potentially reduced or avoided.

    Place, publisher, year, edition, pages
    Springer, 2014
    Series
    Decision Engineering, ISSN 1619-5736 ; 2014
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-73900 (URN)978-3-319-12110-9 (ISBN)
    Note

    On the day of the defence date the status of this article was Manuscript.

    Available from: 2012-01-16 Created: 2012-01-16 Last updated: 2015-01-07Bibliographically approved
  • 19.
    Mökander, Jakob
    Linköping University, Department of Management and Engineering, Industrial Economics. Linköping University, The Institute of Technology.
    Demand Response in the Future Swedish Electricity Market: A typology based on cost, volume and feasibility2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The power balance of an electrical power system is crucial to the quality of the delivered electricity as well as the security of supply. In a scenario where Swedish nuclear power plants are being phased out and replaced by renewable energy sources new constraints are added to the power balance equation since the production of many renewable energy sources, such as wind and solar power, are intermittent by nature. This leads to a situation where the currently available regulating power might have difficulties to manage the increasing frequency fluctuations in the power grid. One possible solution to the problem is to build gas turbines for the purpose of peak power generation capacity. An alternative option would be to increase customer flexibility; that is Demand Response.

    This master thesis investigates how the market for Demand Respond can be designed and which potential Demand Response volumes different policy programs might release. This is done through a mixed approach. Firstly, a scientific review of previously documented Demand Response experiences compares and categorizes different Demand Response programs in a typology based on the parameters cost, volume and feasibility. Subsequently an interview series with different market agents, predominantly through interviews with the Swedish energy intensive industry, identifies the existing Demand Response potential in Sweden and offers the paradigm needed to transfer the results to a future hypothetical situation. The typology of Demand Response programs and estimation of the future industrial Demand Response potential in Sweden are the main new knowledge contributions of this master thesis. The scope however is limited to the Swedish market geographically and focuses on the time horizon 2020-2050. It is also assumed that only existing technologies are likely to be implemented on a large scale over the given time horizon.

    The results of this master thesis suggest that a Real Time Pricing model would realize the largest potential of Demand Response and to a relatively low cost. This solution however requires actions and further development of both the pricing model and in technology. Firstly, all market agents must have free access to real time price information, something that is lacking today. Secondly, a smart grid with hourly meters is required. If policymakers consider security of supply to be more important than a low system cost, Direct Control or a continuation of the Strategic Reserve is to be preferred according to the conclusions of this report.

    Previous studies have placed the existing potential for industrial Demand Response in Sweden between 600 and 900 MW. This report suggests that the available volume is in the upper region of the mentioned interval already today and has potential to rise significantly in the future as industries become more aware of the concept and the transmission grid is becoming more flexible. Another driving force for increased Demand Response volumes are the increased price fluctuations which are expected as a consequence of a greater share of renewable energy sources. For the future Demand Response potential, a cost perspective is introduced and a distinction between different response durations is made. More specifically the results indicate that the potential industrial Demand Response volume will be about 1,500 MW in 2030, given a response duration time of 4 h and a spot price on 2,000 SEK/MWh.

    If 1,500 MW of peak generation capacity could be avoided through active Demand Side Management, it would reduce the system cost with about 350 Million SEK annually. Consequently, there is a business case for Demand Response and the issue is likely to be subject to further investigation and discussion in the future. On the long term however industrial Demand Response must be compared with other flexibility options, e.g. as import/export or energy storages but also residential Demand Response, and is in such case likely to be outcompeted due to its relatively high variable cost of providing capacity. 

  • 20.
    Olstam, Johan
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Statens väg- och transportforskningsinstitut, Trafikanalys och logistik, TAL.
    Carlsson, Arne
    Statens väg- och transportforskningsinstitut, Miljö och trafikanalys, MTA.
    Yahya, Mohammad Reza
    Statens väg- och transportforskningsinstitut, Trafikanalys och logistik, TAL.
    Hastighetsflödessamband för svenska typvägar: förslag till reviderade samband baserat på TMS-mätningar från 2009-20112013Report (Other academic)
    Abstract [en]

    This report presents suggestions for new speed-flow relationships for motorways (MV), low standard motorways (4F), oncoming lane separated highways with grade separated intersections (MML), oncoming lane separated highways with at grade intersections (MLV), and two-lane highways. The suggestions are based on measurements from Trafikverket’s traffic count measuring system TMS in combination with model calculations. The TMS data have, for each road category, been quality checked, processed and analyzed. The data material is presented as speed-flow graphs for personal cars, trucks/buses without trailers and trucks with trailers. A comparison of the current speed-flow relationships and the TMS measurements was then conducted for each road category. The revised set of relationships then constituted the base for the 2012 revision of Trafikverket's publication "Effect calculations for road facilities". The analysis conducted resulted in suggestions to decrease the free flow speed and the travel speed at higher flows for most of the road categories. For motorways also a decrease in capacity is suggested. For oncoming separated highways (both MML and MLV) are minor changes of the capacity suggested. The suggested capacity value is for MML and MLV 1550 vehicles/h independently of speed limit and lane/road width.

  • 21.
    Palmert, Frans
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Gustafsson, David
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Thermomechanical fatigue crack growth in a single crystal nickel base superalloy2019In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 122, p. 184-198Article in journal (Refereed)
    Abstract [en]

    Thermomechanical fatigue crack growth in a single crystal nickel base superalloy was studied. Tests were performed on single edge notched specimens, using in phase and out of phase thermomechanical fatigue cycling with temperature ranges of 100-750°C and 100-850°C and hold times at maximum temperature ranging from 10s to 6h. Isothermal testing at 100°C, 750°C and 850°C was also performed using the same test setup. A compliance-based method is proposed to experimentally evaluate the crack opening stress and thereby estimate the effective stress intensity factor range ΔKeff for both isothermal and nonisothermal conditions. For in phase thermomechanical fatigue, the crack growth rate is increased if a hold time is applied at the maximum temperature. By using the compliance-based crack opening evaluation, this increase in crack growth rate was explained by an increase in the effective stress intensity factor range which accelerated the cycle dependent crack growth. No significant difference in crack growth rate vs ΔKeff was observed between in phase thermomechanical fatigue tests and isothermal tests at the maximum temperature. For out of phase thermomechanical fatigue, the crack growth rate was insensitive to the maximum temperature and also to the length of hold time at maximum temperature. The crack growth rate vs ΔKeff during out of phase thermomechanical fatigue was significantly higher than during isothermal fatigue at the minimum temperature, even though the advancement of the crack presumably occurs at the same temperature. Dissolution of γ′ precipitates and recrystallization at the crack tip during out of phase thermomechanical fatigue is suggested as a likely explanation for this difference in crack growth rate.

    The full text will be freely available from 2021-01-25 17:11
  • 22.
    Syberg, Andreas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Livscykelkostnadsanalys för beläggningar i containerterminaler: en förstudie för bättre beslutsunderlag vid investeringar i terminalytor2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Pontarius AB har tillsammans med Göteborgs Hamn AB identifierat behovet av en utvecklad holistisk modell för bedömning av investeringar i terminalytor. För detta har en första ansats gjorts med den interna livscykelkostnadsanalysmodellen Total Cost of Ownership and Operations (TCOO). Livscykelkostnadsanalys (LCCA) är ett verktyg för att handskas med ett projekts totala kostnader vid investeringsbeslut och bedömning av alternativ. Generella livscykelkostnads-modeller är svåra att ta fram, varför istället utförliga modeller vanligen skapas för specifika områden. För vägbeläggningar, och tillviss del flygplatsbeläggningar, finns utförliga sådana metoder, men för beläggningar i containerterminaler saknas det.

    För att fortsätta utveckling mot en bättre bedömningsmodell för terminalytor syftade studien till att identifiera kostnadsparametrar som sett ur ett livscykelperspektiv påverkar kostnaderna för containerhamnterminalytor. Utifrån dessa analyserades sedan livscykelkostnadsmodellen Total Cost of Ownership and Operations. Stor vikt lades i litteratursökning kring livscykelkostnads-analyser och kostnadsparametrar för containerterminaler. Vidare genomfördes även en intervjustudie mot Göteborgs Hamn, samt granskning av företagsdokument för att studera TCOO-modellen.

    Modeller för livscykelkostnadsanalyser för beläggningar på vägar och flygplatser visades till stor del även kunna appliceras på beläggningar i containerterminaler. Ägarkostnaderna, dvs. designkostnad, konstruktionskostnad, underhållskostnad, och restvärde, för de olika typerna av beläggning är lika. Vid driften av en containerterminal uppstår kostnader relaterade till beläggningen genom ojämnheter i ytan vilket ökar truckkostnaderna och även kan leda till långsammare godshantering. Produktiviteten är en viktig faktor för containerterminaler där faktorer som begränsar produktiviteten och kapaciteten kan leda till inkomstförluster. Vid avstängning av ytor för underhåll så påverkas produktionen stort och extra kostnader uppstår.

    Modellen Total Cost of Ownership and Operations jämfördes mot de identifierade parametrarna i litteraturstudien. Utvecklingspotential med Pontarius modell identifierades vara att följa en mer strukturerad process likt livscykelkostnadsanalysmodeller för vägar och flygplatser, samt en noggrannare identifiering och hantering av operationella kostnader i containerterminalen.

  • 23.
    Wärner, Hugo
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Calmunger, Mattias
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. AB Sandvik Mat Technol, Sweden.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Creep-fatigue interaction in heat resistant austenitic alloys2018In: 12TH INTERNATIONAL FATIGUE CONGRESS (FATIGUE 2018), E D P SCIENCES , 2018, Vol. 165, article id 05001Conference paper (Refereed)
    Abstract [en]

    This work includes an investigation of two commercial austenitic steels: UNS S21500 (Esshete 1250) and UNS S31035 (Sandvik Sanicro (TM) 25). The materials were exposed to isothermal strain controlled fatigue with load controlled dwell time at maximum strain. The testing temperature used was 700 degrees C and the test cycles were performed in tension. Mechanical test data were obtained and analysed in order to define creep-fatigue damage diagrams at failure for the investigated austenitic alloys. During the given conditions, Sanicro 25 showed superior creep-fatigue life, suffered less amount of creep elongation for the same amount of strain amplitude and dwell times compared to Esshete 1250. Both alloys showed creep-fatigue interaction damage for specific test configurations.

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