| 1. |
- Alam, Assad, et al.
(author)
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Cooperative driving according to Scoop
- 2011
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Reports (other academic/artistic)abstract
- KTH Royal Institute of Technology and Scania are entering the GCDC 2011 under the name Scoop –Stockholm Cooperative Driving. This paper is an introduction to their team and to the technical approach theyare using in their prototype system for GCDC 2011.
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| 2. |
- Alam, Assad, et al.
(author)
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Look-Ahead Cruise Control for Heavy Duty Vehicle Platooning
- 2013
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In: Proceedings of the 16th International IEEE Annual Conference onIntelligent Transportation Systems (ITSC 2013). - : IEEE conference proceedings. - 9781479929146 ; , s. 928-935
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Conference paper (peer-reviewed)abstract
- Vehicle platooning has become important for thevehicle industry. Yet conclusive results with respect to thefuel reduction possibilities of platooning remain unclear, inparticular when considering constraints imposed by the topography.The focus of this study is to establish whether itis more fuel-efficient to maintain or to split a platoon that isfacing steep uphill and downhill segments. Two commercialcontrollers, an adaptive cruise controller and a look-aheadcruise controller, are evaluated and alternative novel controlstrategies are proposed. The results show that an improvedfuel-efficiency can be obtained by maintaining the platoonthroughout a hill. Hence, a cooperative control strategy basedon preview information is presented, which initiates the changein velocity at a specific point in the road for all vehiclesrather than simultaneously changing the velocity to maintainthe spacing. A fuel reduction of up to 14% can be obtainedover a steep downhill segment and a more subtle benefit of0.7% improvement over an uphill segment with the proposedcontroller, compared to the combination of the commerciallyavailable cruise controller and adaptive cruise controller thatcould be used for platooning. The findings show that it isboth fuel-efficient and desirable in practice to consider previewinformation of the topography in the control strategy.
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| 4. |
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| 5. |
- Chughtai, Mohsan Niaz, et al.
(author)
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Analysis of Non-Linear Impairments in 40 Gbaud PM DQPSK and D8PSK Transmission
- 2010
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In: ICTON 2010. - : IEEE Press. - 9781424477982 ; , s. 1 -4
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Conference paper (peer-reviewed)abstract
- In this paper, 40 Gbaud transmission of single polarization (SP) and Polarization-Multiplexed (PM), RZ-DQPSK and RZ-D8PSK signals is analyzed numerically. The impact of nonlinear crosstalk arising from the presence of neighbouring intensity-modulated channels is analyzed in terms of required OSNR for the BER of 10-3versus launch power.
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| 6. |
- Chughtai, Mohsan Niaz, et al.
(author)
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Dependence of non-linear impairments on polarization state and baud rate in WDM systems with mixed DQPSK and OOK channels
- 2011
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Conference paper (peer-reviewed)abstract
- In this paper, transmission of Polarization-Multiplexed (PM), RZ-DQPSK is analyzed numerically with copropagation of intensity modulated non return to zero on off keying (NRZ OOK) channels. The dependence of nonlinear crosstalk on baud rate (10 Gbaud, 28 Gbaud and 56 Gbaud) and relative state of polarization (SOPs) of PM RZ DQPSK and neighbouring NRZ OOK channels is analyzed in terms of required OSNR for the BER of 10 -3 versus launch power. From the results we observe that non-linear impairments are highly dependent on relative SOPs and less dependent on baud rates of the PM RZ DQPSK test channel.
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| 7. |
- Chughtai, Mohsan Niaz, et al.
(author)
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Influence of polarization state, baud rate and PMD on non-linear impairments in WDM systems with mixed PM (D)QPSK and OOK channels
- 2012
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In: Optics Express. - : Optical Society of America. - 1094-4087. ; 20:7, s. 8155-8160
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Journal article (peer-reviewed)abstract
- In this paper we numerically investigate nonlinear impairments in a WDM system with mixed PM (D)QPSK and OOK channels. First we analyze the dependence of XPM and XPolM on SOP and baud rate in absence of PMD. In this case we find that the nonlinear impairments are highly dependent on relative SOP between the PM (D)QPSK and neighbouring OOK channels. The dependence on relative SOP is more pronounced in differential detection than in coherent detection. However, with increasing values of PMD this dependence decreases, and non-linear tolerance improves
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| 8. |
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| 9. |
- Flärdh, Oscar, et al.
(author)
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Analysis of a Quasi-Steady Extension to the Turbine Model in Mean Value Engine Models
- 2010
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In: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Conference paper (peer-reviewed)abstract
- The aim to reduce fuel consumption and emissions has been targeted by several approaches. One of them is downsizing, where a small engine is equipped with a turbocharger in order to give the same power as a larger engine, but with less fuel consumption. This in turn requires advanced control systems to take full benefit from the downsizing. Recent hardware advancements have enabled the use of variable geometry turbochargers also on SI engines, pushing the control demands further. This paper investigates possible extensions to control oriented mean value engine models for turbocharged SI-engines, focusing on the turbine. Mean value models do not take the pulsating phenomena in the exhaust manifold into account. This is assumed to cause large model errors, especially for the turbine efficiency and turbine power. The main contribution of this paper is to present an investigation of the effects of incorporating pressure pulses in the mean value model, together with an analysis of the effects of the pulsation on the turbine performance maps. An evaluation of the extended mean value model using measurements on a four cylinder SI engine with a variable geometry turbocharger is also presented. The evaluation show little difference between using pressure pulses and mean values. An analysis of the expression for turbine power shows that, when treating the maps quasi-steady, the calculated turbine power is almost the same when using pressure pulsations as when using just the mean pressure ratio. The analysis also indicates that this is due to the fact that the turbine power is an approximately linear function of the turbine pressure ratio.
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| 10. |
- Flärdh, Oscar, et al.
(author)
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Exhaust pressure modeling and control on an si engine with vgt
- 2014
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In: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 25:1, s. 26-35
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Journal article (peer-reviewed)abstract
- For a turbocharged si engine, the exhaust pressure is of high importance for the gas exchange process as well as for the turbine power. It is therefore important to control the exhaust pressure accurately during load transients. This paper presents and evaluates a nonlinear controller for the exhaust pressure in an si engine equipped with a variable geometry turbine. A mapping from the states, inputs, and disturbances to future outputs is formed, and inverting the input/output relation in this mapping gives a control law. The controller, which can be tuned as a pi controller, utilizes a model for the turbine mass flow capturing the flow characteristics over the operating range. This controller is compared to a linear pi controller and a feedback linearization controller. Evaluation is performed using both simulations and measurements on a real engine, showing the superior behavior of the nonlinear controllers over the linear controller for this problem. Moreover, the presented controller achieves almost as good performance as a feedback linearization controller, but with easier tuning and implementation.
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