| 1. |
- Christoffersen, Lasse Malmkjaer, 1979, et al.
(författare)
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Wing-diffuser interaction on a sports car
- 2011
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Ingår i: SAE Technical Papers. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- Amongst the aerodynamic devices often found on race cars, the diffuser is one of the most important items. The diffuser can work both to reduce drag and also to increase downforce. It has been shown in previously published studies, that the efficiency of the diffuser is a function of the diffuser angle, ground clearance and most importantly, the base pressure. The base pressure of a car is defined by the shape of the car and in particular the shape at the rear end, including the rear wheels. Furthermore, on most race cars, a wing is mounted at the rear end. Since the rear wheels and wing will influence the base pressure it is believed that, for a modern race car, there could be a strong interaction between these items and the diffuser. This work aims to systematically study the interaction between the rear wheels and wing; and the diffuser of a contemporary, sports car type, race vehicle. The work was carried out using computational fluid dynamics and the geometry, that the study was based on, was the Lotus Evora Type 124 CUP car. The car carried detailed chassis components and a complete cooling system. In the study, the diffuser angle was varied over several inclinations, ranging from 3 to 12 degrees. Furthermore, the height of the wing over the "rear deck" of the car was also varied. It was found from the study that the vertical position of the wing over the rear deck of the car had no significant influence on the flow through the diffuser, at the wing heights tested and vice versa, the diffuser showed only little influence on the flow past the rear wing. The diffuser however, had an influence on the base pressure and most importantly; on the downforce generation. At increasing diffuser angles the base pressure was reduced and consequently the downforce was increased. Copyright © 2011 SAE International.
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| 2. |
- Boyraz Baykas, Pinar, 1981, et al.
(författare)
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Multi-sensor Driver Drowsiness Monitoring
- 2008
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 222:11, s. 2041-2062
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Tidskriftsartikel (refereegranskat)abstract
- A system for driver drowsiness monitoring is proposed, using multi-sensor dataacquisition and investigating two decision-making algorithms, namely a fuzzy inference system(FIS) and an artificial neural network (ANN), to predict the drowsiness level of the driver.Drowsiness indicator signals are selected allowing non-intrusive measurements. The experi-mental set-up of a driver-drowsiness-monitoring system is designed on the basis of the sought-after indicator signals. These selected signals are the eye closure via pupil area measurement,gaze vector and head motion acquired by a monocular computer vision system, steering wheelangle, vehicle speed, and force applied to the steering wheel by the driver. It is believed that, byfusing these signals, driver drowsiness can be detected and drowsiness level can be predicted.For validation of this hypothesis, 30 subjects, in normal and sleep-deprived conditions, areinvolved in a standard highway simulation for 1.5 h, giving a data set of 30 pairs. For designing afeature space to be used in decision making, several metrics are derived using histograms andentropies of the signals. An FIS and an ANN are used for decision making on the drowsinesslevel. To construct the rule base of the FIS, two different methods are employed and comparedin terms of performance: first, linguistic rules from experimental studies in literature and,second, mathematically extracted rules by fuzzy subtractive clustering. The drowsiness levelsbelonging to each session are determined by the participants before and after the experiment,and videos of their faces are assessed to obtain the ground truth output for training thesystems. The FIS is able to predict correctly 98 per cent of determined drowsiness states(training set) and 89 per cent of previously unknown test set states, while the ANN has a correctclassification rate of 90 per cent for the test data. No significant difference is observed betweenthe FIS and the ANN; however, the FIS might be considered better since the rule base can beimproved on the basis of new observations.
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| 3. |
- Boyraz Baykas, Pinar, 1981, et al.
(författare)
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Signal Modelling and Hidden Markov Models for Driving Manoeuvre Recognition and Driver Fault Diagnosis in an urban road scenario
- 2007
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Ingår i: IEEE Intelligent Vehicles Symposium, Proceedings. ; , s. 987-992
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Konferensbidrag (refereegranskat)abstract
- Hidden Markov models (HMM) are used to identify a vehicle's manoeuvre sequence and its appropriateness for a given urban road driving situation. One of the novel aspects of this work has been the development of an efficient signal modelling approach to form a context-aware, flexible system which proved to respond well in urban road scenarios, especially in situations where the driver is likely to have an accident due to impaired performance. Another contribution has been to clarify how HMMs can be used not just to recognize vehicle manoeuvres but also to distinguish an impaired driver from a normal one in complex driving contexts. The system has worked well on simulator data and is about to be implemented in the real conditions of an urban trajectory.
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| 4. |
- Christoffersen, Lasse Malmkjaer, 1979, et al.
(författare)
-
Wing-Diffuser Interaction on a Sports Car
- 2011
-
Ingår i: SAE technical paper. SAE 2011 World Congress and Exhibition, Detroit, 12 April 2011. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
-
Konferensbidrag (refereegranskat)abstract
- Amongst the aerodynamic devices often found on race cars, the diffuser is one of the most important items. The diffuser can work both to reduce drag and also to increase downforce. It has been shown in previously published studies, that the efficiency of the diffuser is a function of the diffuser angle, ground clearance and most importantly, the base pressure. The base pressure of a car is defined by the shape of the car and in particular the shape at the rear end, including the rear wheels. Furthermore, on most race cars, a wing is mounted at the rear end. Since the rear wheels and wing will influence the base pressure it is believed that, for a modern race car, there could be a strong interaction between these items and the diffuser.
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