| 1. |
- Jansson, Emil
(författare)
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Challenges with Driverless and Unattended Train Operations
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Demand for transportation continues to increase, for both freight and passenger services. One of the most energy-efficient modes of transportation is rail. One solution to increase the attractiveness of rail transport is to introduce automatic train operation (ATO) with a high grade of automation (GoA). Driverless and unattended train operation could entail positive effects but would also bring challenges when removing the train driver. Thus, there is a need to understand the role of train drivers, especially in unplanned events. The main research objectiveis to understand the train driver roles during unplanned events and the frequency of such events. This thesis includes three papers to fulfill the research objective.This thesis studied delay logs and trackside sensor logs. A qualitative method, thematic analysis, was used to identify themes of the roles performed by train driver from the delay logs. The chi-square test statistical method was used to analyze these trackside sensor logs.Six main categories of tasks for train drivers were identified for unplanned events. Detect, Report, Inspect, Adjust, Manage passengers, and Respond to train orders. Each category was analyzed for each grade of automation by giving the responsibility for each category. The results highlight in a novel way the varied challenges between grade of automation in mainline systems. Detecting abnormalities was the most common task train drivers performed during unplanned events. Train drivers use four human senses to detect abnormalities: sight, hearing, touch, and smell. This indicates the need for onboard sensors. However, the real challenge is in processing all sensor data to gain anaccurate evaluation of any fault. One specific type of unplanned event in which the train driver is needed involves trackside sensor alarms. Freight trains are ten times more likely to trip an alarm than passenger trains. Alarms are more frequent in colder climate zones during winter months. These differences are statistically significant and indicate that not all lines and train types might be suitable for a high grade of automation.If driverless or unattended train operation will become a reality in future, many challenges must be met. This thesis gives deeper understanding of these challenges using a novel way to identify and quantify train driver tasks during unplanned events.
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| 2. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Look-ahead speed planning for heavy-duty vehicle platoons using traffic information
- 2017
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Ingår i: Transportation Research Procedia. - : Elsevier. - 2352-1465. ; 22, s. 561-569
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Tidskriftsartikel (refereegranskat)abstract
- Freight transport is a fast increasing transportation mode due to the economic growth in the world. Heavy-duty vehicles (HDV) have considerably greater fuel consumption, thus making them a suitable target when new policies in road transport emphasize increased energy efficiency and mitigated emission impacts. Intelligent transportation systems, based on emerging V2X communication technology, open new possibilities for developing fuel-efficient driving support functions considering real traffic information. This indicates a large potential of fuel saving and emission reduction for freight transport. This paper studies a dynamic programming-based optimal speed planning considering a maximum acceleration model for HDVs. The optimal speed control is applied for the deceleration case of HDV platoons due to received information on traffic speed reduction ahead. The control can optimize fuel consumption as well as travel time, and theoretical results for the two cases are presented. For maximal fuel saving, a microscopic traffic simulation study is performed for single HDVs and HDV platoons running in real traffic conditions. The results show a decrease in fuel consumption of more than 80% compared to simulations without applying optimal control, while the fuel consumption of other vehicles in the simulation is not significantly affected.
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| 3. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Microscopic and macroscopic simulation of early freight train departures
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden and other countries it is not an uncommon practice that freight trains depart more or less on-demand instead of strictly following a pre-planned timetable. However, the systematic effects of freight trains departing late or, in particular, early has long been a contested issue. Although some microscopic simulation tools currently have the capability to evaluate the effect of freight trains departing before schedule, it has yet not been established how macroscopic simulation tools, capable of fast simulation of nation-wide networks, can manage such tasks. This paper uses a case study on a line between two large freight yards in Sweden to investigate how the results of microscopic and macroscopic simulation, represented by two modern simulation tools, differ when it comes to this particular problem. The main findings are that both the microscopic and the macroscopic tools could replicate the empirical punctuality fairly well, with the macroscopic case study results being closer to the empirical data. Furthermore, allowing early departures of freight trains increased overall freight train punctuality without any major impact on passenger train punctuality, as determined by both tools. The results are encouraging, but further studies are needed to determine if macroscopic simulation is on-par with microscopic simulation.
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| 4. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Microscopic and macroscopic simulation of early freight train departures
- 2022
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden and other countries it is not an uncommon practice that freight trains depart more or less on-demand instead of strictly following a pre-planned timetable. However, the systematic effects of freight trains departing late or (in particular) early has long been a contested issue. Although some microscopic simulation tools currently have the capability to evaluate the effect of freight trains departing before schedule, it has yet not been established how macroscopic simulation tools, capable of fast simulation of nation-wide networks, can manage such tasks. This paper uses a case study on a line between two large freight yards in Sweden to investigate how the results of microscopic and macroscopic simulation, represented by two modern simulation tools, differ when it comes to this particular problem. The main findings are that both the microscopic and the macroscopic tools replicated the empirical punctuality fairly well. Furthermore, allowing early departures of freight trains increased overall freight train punctuality while the passenger train punctuality decreased slightly, as determined by both tools. The results are encouraging, but further studies are needed to determine if macroscopic simulation is on-par with microscopic simulation.
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| 5. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Rail platform allocation for reliable interchanges
- 2024
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Ingår i: Transportation Research Procedia. - : Elsevier BV. - 2352-1465. ; 78, s. 198-205, s. 198-205
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Tidskriftsartikel (refereegranskat)abstract
- Changing trains is a crucial part of many rail journeys, and it is important that arrival and departing trains are allocated close to each other for a swift interchange. Today the platform allocation of trains is often based on local traditions, where trains of the same type to the same destination depart from the same track. In this paper we address the problem of using the platform tracks in the best way, balancing crossing train paths with easy interchanges at the same platform. We use a RailSys model of the station in Norrköping, Sweden, to assess three platform allocation strategies with respect to crossing train paths and train changes at the same platform. Moreover, the capacity utilisation is calculated by a timetable compression-based method. The results show that a platform allocation maximising the changes at the same platform leads to more crossing train paths and higher capacity utilisation. Future work includes more accurate modelling of train connections, assessment of delays through simulation, and a cost-benefit analysis to find the best balance between easy interchanges and conflicting train paths.
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| 6. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Simulating the Punctuality Impacts of Early Freight Train Departures
- 2022
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Ingår i: Proceedings of The 13th World Congress on Railway Research (WCRR). ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Railway traffic usually adheres to a timetable, but in Sweden, around two-thirds of the freight trains depart before they are scheduled, often by hours. Even though they occur in real operations, early departures have rarely been included in simulation studies and the effects on punctuality are not fully investigated. With a macroscopic simulation tool such as PROTON, large networks can be simulated in a short time, which makes the simulation process easier. This paper uses the tool PROTON to perform a macroscopic simulation case study on the Swedish Western mainline to investigate how early departures of freight trains affect punctuality. The resulting output is a marginal overall punctuality improvement of about +0.5 percentage points. In addition, different levels of primary run time and dwell time delays have been used as simulation input, based on empirical data. The resulting ratio between primary and secondary delays appears to vary greatly between different train types, but overall about 30% were primary and 70% secondary. Future work includes modelling and calibration of departure deviations, which vary more between different train types, and where it is more difficult to separate between primary and secondary delays. Separating distributions based on train type or location will also be considered.
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| 7. |
- Johansson, Ingrid, 1990-
(författare)
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Simulation Studies for Improved Efficiency in Road and Rail Freight Transports
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The demand for road and rail freight transport continues to grow with the expanding economy, while the climate crisis requires reduction in greenhouse gas emissions. Therefore, tools and solutions for reducing fossil fuel use and enabling more efficient use of infrastructure are needed. This thesis utilises microscopic and macroscopic traffic simulation as tools to improve certain aspects of road and rail transport planning in the operational, tactical, and strategic planning time horizons.For road freight transports conducted with heavy-duty vehicles, fuel consumption can be reduced by smarter driving. Strategic planning concerning introduction of intelligent and connected vehicles is needed, along with planning of actual vehicle operations. Microscopic road traffic simulation is utilised to show that heavy-duty vehicle platooning, which lowers the fuel consumption through reduced aerodynamic drag, can be conducted on two-lane highway stretches without disturbing surrounding traffic. Further, substantial reduction of the fuel consumption can be achieved by applying fuel-optimal deceleration trajectories, assuming available information about the traffic situation ahead.Shifting freight transports from roads to railways is another possible measure to reduce emissions. Previous simulation studies of railway traffic has mainly focused on passenger trains, combined with not including freight train departures before the scheduled timetable, even though it commonly occurs in Sweden. Therefore, both microscopic and macroscopic railway traffic simulation, with and without allowing early freight train departures, is conducted in a case study. The resulting freight train punctuality is closer to empirical punctuality when early departures are included.A modal shift from road to rail transport increases capacity utilisation of railway networks, and is only possible within available capacity. Therefore, reliable methods for capacity analysis are needed. A method for capacity analysis is introduced and evaluated, with particular focus on railway station analysis. An advantage of this method is it can be used in tactical and strategic planning of future timetables and infrastructure.
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| 8. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Strategic assessment of railway station capacity – Further development of a UIC 406-based approach considering timetable uncertainty
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Railway capacity analysis aims to assess the number of trains that can reasonably be operated on a given infrastructure. The UIC timetable compression method is a widely accepted standard for evaluating and comparing the infrastructure utilization of timetable concepts. Originally designed for capacity analysis of railway lines it has been adapted to railway stations in the second version of UIC Code 406. In this paper we discuss further developments of a statistical approach for station capacity analysis using UIC-compression methodology suited for long-term infrastructure planning. It allows to assess the capability of railway station track layouts based on a distributional analysis of different timetable variants derived from a given traffic concept. As a result, the infrastructure’s flexibility to cope with different timetable variants – which is particularly relevant for deregulated transport markets – can be tested. To better account for train-interdependencies, stations are considered in their entirety and a new time-window oriented gap-filling approach is introduced that preserves the overall timetable structure while allowing to perform local optimization of infrastructure occupation. The approach is demonstrated in a case study based on the Southern part of the Swedish railway network.
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| 9. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Strategic assessment of railway station capacity – Further development of a UIC 406-based approach considering timetable uncertainty
- 2021
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Konferensbidrag (refereegranskat)abstract
- Railway capacity analysis aims to assess the number of trains that can reasonably be operated on a given infrastructure. The UIC timetable compression method is a widely accepted standard for evaluating and comparing the infrastructure utilization of timetable concepts. Originally designed for capacity analysis of railway lines it has been adapted to railway stations in the second version of UIC Code 406. In this paper we discuss further developments of a statistical approach for station capacity analysis using UIC-compression methodology suited for long-term infrastructure planning. It allows to assess the capability of railway station track layouts based on a distributional analysis of different timetable variants derived from a given traffic concept. As a result, the infrastructure’s flexibility to cope with different timetable variants – which is particularly relevant for deregulated transport markets –can be tested. To better account for train-interdependencies, stations are considered in their entirety and a new time-window oriented gap-filling approach is introduced that preserves the overall timetable structure while allowing to perform local optimization of infrastructure occupation. The approach is demonstrated in a case study based on the Southern part of the Swedish railway network.
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| 10. |
- Komai, Ali, 1987, et al.
(författare)
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White Adipocyte Adiponectin Exocytosis Is Stimulated via beta(3)-Adrenergic Signaling and Activation of Epac1: Catecholamine Resistance in Obesity and Type 2 Diabetes
- 2016
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 65:11, s. 3301-3313
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the physiological regulation of adiponectin exocytosis in health and metabolic disease by a combination of membrane capacitance patch-clamp recordings and biochemical measurements of short-term (30-min incubations) adiponectin secretion. Epinephrine or the beta(3)-adrenergic receptor (AR) agonist CL 316,243 (CL) stimulated adiponectin exocytosis/secretion in cultured 3T3-L1 and in primary subcutaneous mouse adipocytes, and the stimulation was inhibited by the Epac (Exchange Protein directly Activated by cAMP) antagonist ESI-09. The beta(3)AR was highly expressed in cultured and primary adipocytes, whereas other ARs were detected at lower levels. 3T3-L1 and primary adipocytes expressed Epac1, whereas Epac2 was undetectable. Adiponectin secretion could not be stimulated by epinephrine or CL in adipocytes isolated from obese/type 2 diabetic mice, whereas the basal (unstimulated) adiponectin release level was elevated twofold. Gene expression of beta(3)AR and Epac1 was reduced in adipocytes from obese animals, and corresponded to a respective similar to 35% and similar to 30% reduction at the protein level. Small interfering RNA-mediated knockdown of beta(3)AR (similar to 60%) and Epac1 (similar to 50%) was associated with abrogated catecholamine-stimulated adiponectin secretion. We propose that adiponectin exocytosis is stimulated via adrenergic signaling pathways mainly involving beta(3)ARs. We further suggest that adrenergically stimulated adiponectin secretion is disturbed in obesity/type 2 diabetes as a result of the reduced expression of beta(3)ARs and Epac1 in a state we define as "catecholamine resistance."
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| 11. |
- Lu, Yong, 1989, et al.
(författare)
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Propagating Wigner-Negative States Generated from the Steady-State Emission of a Superconducting Qubit
- 2021
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 126:25
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally demonstrate the steady-state generation of propagating Wigner-negative states from a continuously driven superconducting qubit. We reconstruct the Wigner function of the radiation emitted into propagating modes defined by their temporal envelopes, using digital filtering. For an optimized temporal filter, we observe a large Wigner logarithmic negativity, in excess of 0.08, in agreement with theory. The fidelity between the theoretical predictions and the states generated experimentally is up to 99%, reaching state-of-the-art realizations in the microwave frequency domain. Our results provide a new way to generate and control nonclassical states, and may enable promising applications such as quantum networks and quantum computation based on waveguide quantum electrodynamics.
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| 12. |
- Palmqvist, Carl William, et al.
(författare)
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A method to separate primary and secondary train delays in past and future timetables using macroscopic simulation
- 2023
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Ingår i: Transportation Research Interdisciplinary Perspectives. - : Elsevier. - 2590-1982. ; 17, s. 100747-100747
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Tidskriftsartikel (refereegranskat)abstract
- Punctuality is a key factor in railway operations and is affected by both primary and secondary delays to differing degrees. Being able to separate these two types of delays is very important when simulating operations, and when conducting punctuality improvement efforts. However, it is not easy to estimate the relative proportions of primary versus secondary delays using historical data. In this paper, we demonstrate a method that uses repeated runs of a macroscopic simulation tool to estimate what share of delays has been primary or secondary. Using the Swedish region of Skåne as a case study, we estimate that about 36% of delays in 2019 were primary, leaving 64% as secondary. We further show that in order for operations to reach the targeted level of punctuality, 95% instead of the observed 87%, primary delays would have had to be cut by half. Using a draft timetable for 2025, we also simulate what the punctuality would be given different assumptions of primary delays. Assuming the same level of primary delays in 2025 as in 2019, we estimate that the punctuality would drop by a further 5 percentage points due to increased density of operations. In order to reach the punctuality target of 95% in 2025, primary delays would instead need to be reduced by two-thirds. At the request of the infrastructure manager, we also show the predicted geographical distribution of secondary delays in this future timetable. Our results highlight the need for drastic delay reduction measures to reach set targets.
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| 13. |
- Quijandria Diaz, Isaac Fernando, 1982, et al.
(författare)
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Steady-State Generation of Wigner-Negative States in One-Dimensional Resonance Fluorescence
- 2018
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 121:26
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Tidskriftsartikel (refereegranskat)abstract
- In this work we demonstrate numerically that the nonlinearity provided by a continuously driven two-level system allows for the generation of Wigner-negative states of the electromagnetic field confined in one spatial dimension. Wigner-negative states, also known as Wigner nonclassical states, are desirable for quantum information protocols beyond the scope of classical computers. Focusing on the steady-state emission from the two-level system, we find the largest negativity at the drive strength where the coherent reflection vanishes.
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| 14. |
- Strandberg, Ingrid, 1990, et al.
(författare)
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Numerical study of Wigner negativity in one-dimensional steady-state resonance fluorescence
- 2019
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 100:6
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Tidskriftsartikel (refereegranskat)abstract
- In a numerical study, we investigate the steady-state generation of nonclassical states of light from a coherently driven two-level atom in a one-dimensional waveguide. Specifically, we look for states with a negative Wigner function, since such nonclassical states are a resource for quantum information processing applications, including quantum computing. We find that a waveguide terminated by a mirror at the position of the atom can provide Wigner-negative states, while an infinite waveguide yields strictly positive Wigner functions. Moreover, our paper reveals a connection between the purity of a quantum state and its Wigner negativity. We also analyze the effects of decoherence on the negativity of a state.
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| 15. |
- Strandberg, Ingrid, 1990, et al.
(författare)
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Wigner negativity in the steady-state output of a Kerr parametric oscillator
- 2021
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Ingår i: Physical Review Research. - 2643-1564. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- The output field from a continuously driven linear parametric oscillator may exhibit considerably more squeezing than the intracavity field. Inspired by this fact, we explore the nonclassical features of the steady-state output field of a driven nonlinear Kerr parametric oscillator using a temporal wave packet mode description. Utilizing a new numerical method, we have access to the density matrix of arbitrary wave packet modes. Remarkably, we find that even though the steady-state cavity field is always characterized by a positive Wigner function, the output may exhibit Wigner negativity, depending on the properties of the selected mode.
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| 16. |
- Zinser, Markus, et al.
(författare)
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PRISM: A Macroscopic Monte Carlo Railway Simulation
- 2019
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Ingår i: Proceedings of The 12th World Congress on Railway Research (WCRR).
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Konferensbidrag (refereegranskat)abstract
- The current state-of-the-art in timetable analysis in the presence of disturbances is to use railway microsimulation, which typically yields detailed results on infrastructure or timetable performance. However, microscopic simulation is time-consuming and requires a detailed infrastructure model and expert knowledge to run adequately. This paper outlines a macroscopic approach which aims at reducing execution time by restricting the level of detail. A first prototype was developed which is able simulate one day of operation on the German railway network with about 40,000 trains in less than a minute. The approach has been studied in detail on that network. Several years of operational data have been analyzed to generate input for the macroscopic simulation. In the results, we describe our analysis tools and compare distributions of the simulation to operational data. It was found that the simulation describes real operational train data very well.
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