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- Bianchi Piccinini, Giulio, 1982, et al.
(författare)
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How Do Drivers Respond to Silent Automation Failures? Driving Simulator Study and Comparison of Computational Driver Braking Models
- 2020
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Ingår i: Human Factors. - Chalmers University of Technology, Gothenburg, Sweden.; Volvo Group Trucks Technology, Gothenburg, Sweden.; Virginia Tech Transportation Institute, Blacksburg, USA.; University of Leeds, UK.; VTI, Gothenburg, Sweden. : SAGE Publications. - 1547-8181 .- 0018-7208. ; 62:7, s. 1212-1229
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This paper aims to describe and test novel computational driver models, predicting drivers’ brake reaction times (BRTs) to different levels of lead vehicle braking, during driving with cruise control (CC) and during silent failures of adaptive cruise control (ACC). Background: Validated computational models predicting BRTs to silent failures of automation are lacking but are important for assessing the safety benefits of automated driving. Method: Two alternative models of driver response to silent ACC failures are proposed: a looming prediction model, assuming that drivers embody a generative model of ACC, and a lower gain model, assuming that drivers’ arousal decreases due to monitoring of the automated system. Predictions of BRTs issued by the models were tested using a driving simulator study. Results: The driving simulator study confirmed the predictions of the models: (a) BRTs were significantly shorter with an increase in kinematic criticality, both during driving with CC and during driving with ACC; (b) BRTs were significantly delayed when driving with ACC compared with driving with CC. However, the predicted BRTs were longer than the ones observed, entailing a fitting of the models to the data from the study. Conclusion: Both the looming prediction model and the lower gain model predict well the BRTs for the ACC driving condition. However, the looming prediction model has the advantage of being able to predict average BRTs using the exact same parameters as the model fitted to the CC driving data. Application: Knowledge resulting from this research can be helpful for assessing the safety benefits of automated driving.
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| 2. |
- Persson, Gustav, et al.
(författare)
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Splenic contraction and cardiovascular responses are augmented during apnea compared to rebreathing in humans
- 2023
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- The spleen contracts during apnea, releasing stored erythrocytes, thereby increasing systemic hemoglobin concentration (Hb). We compared apnea and rebreathing periods, of equal sub-maximal duration (mean 137 s; SD 30), in eighteen subjects to evaluate whether respiratory arrest or hypoxic and hypercapnic chemoreceptor stimulation is the primary elicitor of splenic contraction and cardiovascular responses during apnea. Spleen volume, Hb, cardiovascular variables, arterial (SaO2), cerebral (ScO2), and deltoid muscle oxygen saturations (SmO2) were recorded during the trials and end-tidal partial pressure of oxygen (PETO2) and carbon dioxide (PETCO2) were measured before and after maneuvers. The spleen volume was smaller after apnea, 213 (89) mL, than after rebreathing, 239 (95) mL, corresponding to relative reductions from control by 20.8 (17.8) % and 11.6 (8.0) %, respectively. The Hb increased 2.4 (2.0) % during apnea, while there was no significant change with rebreathing. The cardiovascular responses, including bradycardia, decrease in cardiac output, and increase in total peripheral resistance, were augmented during apnea compared to during rebreathing. The PETO2 was higher, and the PETCO2 was lower, after apnea compared to after rebreathing. The ScO2 was maintained during maneuvers. The SaO2 decreased 3.8 (3.1) % during apnea, and even more, 5.4 (4.4) %, during rebreathing, while the SmO2 decreased less during rebreathing, 2.2 (2.8) %, than during apnea, 8.3 (6.2) %. We conclude that respiratory arrest per se is an important stimulus for splenic contraction and Hb increase during apnea, as well as an important initiating factor for the apnea-associated cardiovascular responses and their oxygen-conserving effects.
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| 3. |
- Williamsson, Jon, 1978, et al.
(författare)
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Feasibility study of the electrification of the urban goods distribution transport system, part II
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Based on the results from FFI project Feasibility study of the electrification of the urban goods distribution transport system (Vinnova reg. no. 2011-01803), this project aimed to investigate how urban goods distribution fleets can be electrified and how new logistics solutions and incentives can influence the transition in a positive way, considering the year 2015, 2020 and 2025. The project is divided into five work packages (WP). The purpose of the first work package, WP1 Fleet Electrification Study, was to evaluate at what rate it is possible for urban goods distribution fleets to become electrified. WP2, Service Impact Evaluation, is a description of ICT services to support electric trucks for goods distribution in cities. The purpose of WP3, Comparative Fleet Electrification Case and Best Practice Investigation, was to compare the electrification case for TGM/Bäckebol in Gothenburg to a reference case in France and to the findings from research and demonstration projects within Europe. WP4, Method Description, package had two purposes. First, it aimed to broadly describe, from a project management perspective, how the project was executed. Second, it presents a review of the project based on the members’ views on how the project was conducted. Finally, WP5, Project Management, included the operative project management activities in the different work packages as well as administrative work such as financial reporting and communications on project progress and results. The project results show that it is difficult for the EVs to compete in 2015 considering a replacement of the diesel trucks with all-electric trucks. However, in 2020 the switch to an EV produces a small profit. This positive outcome for the EV is repeated in 2025 over 8 years of operation. Comparing the results, the two shifts solution never did get financially competitive with the diesel vehicle used in one shift. The reason for this was that the cost of unsocial hours was greater than the benefit of increased utilization of the EVs. Keeping the amount of unsocial hours down, while maximizing the utilization rate of the EV is therefore paramount. In other cities than Gothenburg, where congestion causes severe delays, the efficiency gained by distributing goods off-hours might balance the higher salary costs. The starting point in both the previous and in this project was the introduction of new technology to reduce the negative environmental impact of transports. As the project progressed it became clear that many parameters, other than strictly technological ones, influence the possibility to make a transition to electric distribution. One example, as described above, is the case of off-hour distribution, where the increased salary cost was too high to make the business case profitable. Another example is the limited range of electric vehicles. As the cost competitiveness of electric vehicles benefit greatly from specialization, the business relationship between the transport operator and the shippers becomes more important than in the case of a diesel vehicle. Long term assignments with well-defined transport routes are preferable to be able to use the vehicles long term and dare to take the higher investment cost.
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