| 1. |
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| 2. |
- Aronsson, Martin, et al.
(author)
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An Efficient MIP Model for Locomotive Routing and Scheduling
- 2010. - 9
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Conference paper (peer-reviewed)abstract
- This paper presents a MIP model for a locomotive routing and scheduling problem from the domain of freight railways. Innovative features of the model include the use of binary variables to separate the integer and continuous parts of the problem to maintain the flow character of the integer part of the problem. The model has been developed with, and has found practical Green Cargo, the largest rail freight operator in Sweden.
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| 3. |
- Arvidsson, Åke, et al.
(author)
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Tracking user terminals in a mobile communication network
- 2011. - 7
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Patent (pop. science, debate, etc.)abstract
- There is provided a method of tracking user terminals in a mobile communication network. The method comprising, at a tracking node, determining that a user terminal is located in a tracking area, storing data associated with the tracking area, the data comprising a number of observations of all user terminals at the tracking area at a first time, receiving a page response from the user terminal located in one of the tracking area and a further tracking area, and in the event that the user terminal remains located at the tracking area, updating the data to include the number of page responses received at the tracking area after a first time interval, and in the event that the user terminal is located at the further tracking area, updating the data to include the number of page responses received at the further tracking area after the first time interval.
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| 4. |
- Bohlin, Markus, et al.
(author)
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Searching for gas turbine maintenance schedules
- 2010
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In: The AI Magazine. - : Wiley. - 0738-4602. ; 31:1, s. 21-36
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Journal article (peer-reviewed)abstract
- Preventive-maintenance schedules occurring in industry are often suboptimal with regard to maintenance coallocation, loss-of-production costs, and availability. We describe the implementation and deployment of a software decision support, tool for the maintenance planning of gas turbines, with the goal of reducing the direct maintenance costs and the often costly production losses during maintenance down time. The optimization problem is formally defined, and we argue that the feasibility version is NP-complete. We outline a heuristic algorithm that can quickly solve the problem for practical purposes and validate the approach on a real-world scenario based on an oil production facility. We also compare the performance of our algorithm with result's from using integer programming and d'iscuss the deployment of the application. The experimental results indicate that down time reductions up to 65 percent can be achieved, compared to traditional preventive maintenance. In addition, the use of our tool is expected to improve availability by up to 1 percent and to reduce the number of planned maintenance days by 12 percent. Compared to an integer programming approach, our algorithm is not optimal but is much faster and produces results that are useful in practice. Our test results and SIT AB's estimates based on operational use both indicate that significant savings can be achieved by using our software tool, compared to maintenance plans with fixed intervals.
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| 5. |
- Forsgren, Malin, et al.
(author)
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The Maraca: a tool for minimizing resource conflicts in a non-periodic railway timetable
- 2011. - 9
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Conference paper (peer-reviewed)abstract
- While mathematical optimization and operations research receive growing attention in the railway sector, computerized timetabling tools that actually make significant use of optimization remain relatively rare. SICS has developed a prototype tool for non-periodic timetabling that minimizes resource conflicts, enabling the user to focus on the strategic decisions. The prototype is called the Maraca and has been used and evaluated during the railway timetabling construction phase at the Swedish Transport Administration between April and September 2010.
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| 6. |
- Görnerup, Olof, et al.
(author)
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Autonomous accident monitoring using cellular network data
- 2013
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In: ISCRAM 2013 Conference Proceedings - 10th International Conference on Information Systems for Crisis Response and Management. - : Karlsruher Institut fur Technologie (KIT). - 9783923704804 ; , s. 638-646
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Conference paper (peer-reviewed)abstract
- Mobile communication networks constitute large-scale sensor networks that generate huge amounts of data that can be refined into collective mobility patterns. In this paper we propose a method for using these patterns to autonomously monitor and detect accidents and other critical events. The approach is to identify a measure that is approximately time-invariant on short time-scales under regular conditions, estimate the short and long-term dynamics of this measure using Bayesian inference, and identify sudden shifts in mobility patterns by monitoring the divergence between the short and long-term estimates. By estimating long-term dynamics, the method is also able to adapt to long-term trends in data. As a proof-of-concept, we apply this approach in a vehicular traffic scenario, where we demonstrate that the method can detect traffic accidents and distinguish these from regular events, such as traffic congestions.
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| 7. |
- Holmborn, Katarina, et al.
(author)
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On the Roles and Regulation of Chondroitin Sulfate and Heparan Sulfate in Zebrafish Pharyngeal Cartilage Morphogenesis
- 2012
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:40, s. 33905-33916
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Journal article (peer-reviewed)abstract
- The present study addresses the roles of heparan sulfate (HS) proteoglycans and chondroitin sulfate (CS) proteoglycans in the development of zebrafish pharyngeal cartilage structures. uxs1 and b3gat3 mutants, predicted to have impaired biosynthesis of both HS and CS because of defective formation of the common proteoglycan linkage tetrasaccharide were analyzed along with ext2 and extl3 mutants, predicted to have defective HS polymerization. Notably, the effects on HS and CS biosynthesis in the respective mutant strains were shown to differ from what had been hypothesized. In uxs1 and b3gat3 mutant larvae, biosynthesis of CS was shown to be virtually abolished, whereas these mutants still were capable of synthesizing 50% of the HS produced in control larvae. extl3 and ext2 mutants on the other hand were shown to synthesize reduced amounts of hypersulfated HS. Further, extl3 mutants produced higher levels of CS than control larvae, whereas morpholino-mediated suppression of csgalnact1/csgalnact2 resulted in increased HS biosynthesis. Thus, the balance of the Extl3 and Csgalnact1/Csgalnact2 proteins influences the HS/CS ratio. A characterization of the pharyngeal cartilage element morphologies in the single mutant strains, as well as in ext2;uxs1 double mutants, was conducted. A correlation between HS and CS production and phenotypes was found, such that impaired HS biosynthesis was shown to affect chondrocyte intercalation, whereas impaired CS biosynthesis inhibited formation of the extracellular matrix surrounding chondrocytes.
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| 8. |
- Kreuger, Per, et al.
(author)
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zCap : a zero configuration adaptive paging and mobility management mechanism
- 2013. - 7
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In: International Journal of Network Management. - : Wiley. - 1055-7148 .- 1099-1190. ; 23:4, s. 235-258
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Journal article (peer-reviewed)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for user equipment localisation. Locating users within these areas involves broadcast search (paging), which consumes radio bandwidth but reduces the user equipment signalling required for mobility management. Tracking areas are today manually configured, hard to adapt to local mobility and influence the load on several key resources in the network. We propose a decentralised and self-adaptive approach to mobility management based on a probabilistic model of local mobility. By estimating the parameters of this model from observations of user mobility collected online, we obtain a dynamic model from which we construct local neighbourhoods of cells where we are most likely to locate user equipment. We propose to replace the static tracking areas of current systems with neighbourhoods local to each cell. The model is also used to derive a multi-phase paging scheme, where the division of neighbourhood cells into consecutive phases balances response times and paging cost. The complete mechanism requires no manual tracking area configuration and performs localisation efficiently in terms of signalling and response times. Detailed simulations show that significant potential gains in localisation effi- ciency are possible while eliminating manual configuration of mobility management parameters. Variants of the proposal can be implemented within current (LTE) standards.
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| 9. |
- Kreuger, Per, et al.
(author)
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Zero configuration adaptive paging (zCap)
- 2012
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In: VTC Fall 2012. - : IEEE Communications Society. - 9781467318792
-
Conference paper (peer-reviewed)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for handset localisation. This management parameter is manually configured and maintained and is not regularly adapted to changes in use patterns. We present a decentralised approach to localisation, based on a self-adaptive probabilistic mobility model. Estimates of model parameters are built from observations of mobility patterns collected online using a distributed algorithm. Based on these estimates, dynamic local neighbourhoods of cells are formed and maintained by the mobility management entities of the network. These neighbourhoods replace the static tracking areas used in current implementations by using the tracking area list facility of LTE. The model is also used to derive a multi phase paging scheme, where the division of cells into consecutive phases is optimal with respect to a set balance between response times and paging cost. The approach requires no manual tracking area configuration, and performs localisation efficiently in terms of number of location updates, page
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| 10. |
- Kreuger, Per, et al.
(author)
-
Zero configuration adaptive paging (zCap)
- 2012. - 14
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In: IEEE Vehicular Technology Conference. - : IEEE. - 9781467318815
-
Conference paper (peer-reviewed)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for handset localisation. This management parameter is manually configured and maintained and is not regularly adapted to changes in use patterns. We present a decentralised approach to localisation, based on a self-adaptive probabilistic mobility model. Estimates of model parameters are built from observations of mobility patterns collected on- line using a distributed algorithm. Based on these estimates, dynamic local neighbourhoods of cells are formed and maintained by the mobility management entities of the network. These neighbourhoods replace the static tracking areas used in current implementations by using the tracking area list facility of LTE. The model is also used to derive a multi phase paging scheme, where the division of cells into consecutive phases is optimal with respect to a set balance between response times and paging cost. The approach requires no manual tracking area configuration, and performs localisation efficiently in terms of number of location updates, page messages per localisation request and response times.
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| 12. |
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