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Sample records for driving simulator study

  1. Can We Study Autonomous Driving Comfort in Moving-Base Driving Simulators? A Validation Study.

    PubMed

    Bellem, Hanna; Klüver, Malte; Schrauf, Michael; Schöner, Hans-Peter; Hecht, Heiko; Krems, Josef F

    2017-05-01

    To lay the basis of studying autonomous driving comfort using driving simulators, we assessed the behavioral validity of two moving-base simulator configurations by contrasting them with a test-track setting. With increasing level of automation, driving comfort becomes increasingly important. Simulators provide a safe environment to study perceived comfort in autonomous driving. To date, however, no studies were conducted in relation to comfort in autonomous driving to determine the extent to which results from simulator studies can be transferred to on-road driving conditions. Participants ( N = 72) experienced six differently parameterized lane-change and deceleration maneuvers and subsequently rated the comfort of each scenario. One group of participants experienced the maneuvers on a test-track setting, whereas two other groups experienced them in one of two moving-base simulator configurations. We could demonstrate relative and absolute validity for one of the two simulator configurations. Subsequent analyses revealed that the validity of the simulator highly depends on the parameterization of the motion system. Moving-base simulation can be a useful research tool to study driving comfort in autonomous vehicles. However, our results point at a preference for subunity scaling factors for both lateral and longitudinal motion cues, which might be explained by an underestimation of speed in virtual environments. In line with previous studies, we recommend lateral- and longitudinal-motion scaling factors of approximately 50% to 60% in order to obtain valid results for both active and passive driving tasks.

  2. Driver performance approaching and departing curves: driving simulator study.

    PubMed

    Bella, Francesco

    2014-01-01

    This article reports the outcomes of a driving simulator study on the driver performance approaching and departing curves. The study aimed to analyze driver performance in the tangent-curve-tangent transition and verify the assumption of constant speed in a curve that is commonly used in the operating speed profiles; test whether the 85th percentile of acceleration and deceleration rates experienced by drivers and the acceleration and acceleration rates obtained from the operating speeds are equivalent; find the explanatory variables associated with the 85th percentile of deceleration and acceleration rates experienced by drivers when approaching and departing horizontal curves and provide predicting models of these rates. A driving simulator study was carried out. Drivers' speeds were recorded on 26 configurations of the tangent-curve-tangent transition of 3 2-lane rural roads implemented in the CRISS (Inter-University Research Center for Road Safety) driving simulator; 856 speed profiles were analyzed. The main results were the following: The simplified assumption of the current operating speed profiles that the speed on the circular curve is constant and equal to that at midpoint can be considered admissible; The 85th percentile of deceleration and acceleration rates exhibited by each driver best reflect the actual driving performance in the tangent-curve-tangent transition; Two models that predict the expected 85th percentile of the deceleration and acceleration rates experienced by drivers were developed. The findings of the study can be used in drawing operating speed profiles that best reflect the actual driving performance and allow a more effective safety evaluation of 2-lane rural roads.

  3. Landscape heritage objects' effect on driving: a combined driving simulator and questionnaire study.

    PubMed

    Antonson, Hans; Ahlström, Christer; Mårdh, Selina; Blomqvist, Göran; Wiklund, Mats

    2014-01-01

    According to the literature, landscape (panoramas, heritage objects e.g. landmarks) affects people in various ways. Data are primarily developed by asking people (interviews, photo sessions, focus groups) about their preferences, but to a lesser degree by measuring how the body reacts to such objects. Personal experience while driving a car through a landscape is even more rare. In this paper we study how different types of objects in the landscape affect drivers during their drive. A high-fidelity moving-base driving simulator was used to measure choice of speed and lateral position in combination with stress (heart rate measure) and eye tracking. The data were supplemented with questionnaires. Eighteen test drivers (8 men and 10 women) with a mean age of 37 were recruited. The test drivers were exposed to different new and old types of landscape objects such as 19th century church, wind turbine, 17th century milestone and bus stop, placed at different distances from the road driven. The findings are in some respect contradictory, but it was concluded that that 33% of the test drivers felt stressed during the drive. All test drivers said that they had felt calm at times during the drive but the reason for this was only to a minor degree connected with old and modern objects. The open landscape was experienced as conducive to acceleration. Most objects were, to a small degree, experienced (subjective data) as having a speed-reducing effect, much in line with the simulator data (objective data). Objects close to the road affected the drivers' choice of' lateral position. No significant differences could be observed concerning the test drivers' gaze between old or modern objects, but a significant difference was observed between the test drivers' gaze between road stretches with faraway objects and stretches without objects. No meaningful, significant differences were found for the drivers' stress levels as measured by heart rate.

  4. Speed behaviour in work zone crossovers. A driving simulator study.

    PubMed

    Domenichini, Lorenzo; La Torre, Francesca; Branzi, Valentina; Nocentini, Alessandro

    2017-01-01

    Reductions in speed and, more critically, in speed variability between vehicles are considered an important factor to reduce crash risk in work zones. This study was designed to evaluate in a virtual environment the drivers' behaviour in response to nine different configurations of a motorway crossover work zone. Specifically, the speed behaviour through a typical crossover layout, designed in accordance with the Italian Ministerial Decree 10 July 2002, was compared with that of eight alternative configurations which differ in some characteristics such as the sequence of speed limits, the median opening width and the lane width. The influence of variable message signs, of channelizing devices and of perceptual treatments based on Human Factor principles were also tested. Forty-two participants drove in driving simulator scenarios while data on their speeds and decelerations were collected. The results indicated that drivers' speeds are always higher than the temporary posted speed limits for all configurations and that speeds decreases significantly only within the by-passes. However the implementation of higher speed limits, together with a wider median opening and taller channelization devices led to a greater homogeneity of the speeds adopted by the drivers. The presence of perceptual measures generally induced both the greatest homogenization of speeds and the largest reductions in mean speed values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Text messaging during simulated driving.

    PubMed

    Drews, Frank A; Yazdani, Hina; Godfrey, Celeste N; Cooper, Joel M; Strayer, David L

    2009-10-01

    This research aims to identify the impact of text messaging on simulated driving performance. In the past decade, a number of on-road, epidemiological, and simulator-based studies reported the negative impact of talking on a cell phone on driving behavior. However, the impact of text messaging on simulated driving performance is still not fully understood. Forty participants engaged in both a single task (driving) and a dual task (driving and text messaging) in a high-fidelity driving simulator. Analysis of driving performance revealed that participants in the dual-task condition responded more slowly to the onset of braking lights and showed impairments in forward and lateral control compared with a driving-only condition. Moreover, text-messaging drivers were involved in more crashes than drivers not engaged in text messaging. Text messaging while driving has a negative impact on simulated driving performance. This negative impact appears to exceed the impact of conversing on a cell phone while driving. The results increase our understanding of driver distraction and have potential implications for public safety and device development.

  6. Simulated Driving Assessment (SDA) for teen drivers: results from a validation study.

    PubMed

    McDonald, Catherine C; Kandadai, Venk; Loeb, Helen; Seacrist, Thomas S; Lee, Yi-Ching; Winston, Zachary; Winston, Flaura K

    2015-06-01

    Driver error and inadequate skill are common critical reasons for novice teen driver crashes, yet few validated, standardised assessments of teen driving skills exist. The purpose of this study is to evaluate the construct and criterion validity of a newly developed Simulated Driving Assessment (SDA) for novice teen drivers. The SDA's 35 min simulated drive incorporates 22 variations of the most common teen driver crash configurations. Driving performance was compared for 21 inexperienced teens (age 16-17 years, provisional license ≤90 days) and 17 experienced adults (age 25-50 years, license ≥5 years, drove ≥100 miles per week, no collisions or moving violations ≤3 years). SDA driving performance (Error Score) was based on driving safety measures derived from simulator and eye-tracking data. Negative driving outcomes included simulated collisions or run-off-the-road incidents. A professional driving evaluator/instructor (DEI Score) reviewed videos of SDA performance. The SDA demonstrated construct validity: (1) teens had a higher Error Score than adults (30 vs. 13, p=0.02); (2) For each additional error committed, the RR of a participant's propensity for a simulated negative driving outcome increased by 8% (95% CI 1.05 to 1.10, p<0.01). The SDA-demonstrated criterion validity: Error Score was correlated with DEI Score (r=-0.66, p<0.001). This study supports the concept of validated simulated driving tests like the SDA to assess novice driver skill in complex and hazardous driving scenarios. The SDA, as a standard protocol to evaluate teen driver performance, has the potential to facilitate screening and assessment of teen driving readiness and could be used to guide targeted skill training. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  7. Simulated Driving Assessment (SDA) for Teen Drivers: Results from a Validation Study

    PubMed Central

    McDonald, Catherine C.; Kandadai, Venk; Loeb, Helen; Seacrist, Thomas S.; Lee, Yi-Ching; Winston, Zachary; Winston, Flaura K.

    2015-01-01

    Background Driver error and inadequate skill are common critical reasons for novice teen driver crashes, yet few validated, standardized assessments of teen driving skills exist. The purpose of this study was to evaluate the construct and criterion validity of a newly developed Simulated Driving Assessment (SDA) for novice teen drivers. Methods The SDA's 35-minute simulated drive incorporates 22 variations of the most common teen driver crash configurations. Driving performance was compared for 21 inexperienced teens (age 16–17 years, provisional license ≤90 days) and 17 experienced adults (age 25–50 years, license ≥5 years, drove ≥100 miles per week, no collisions or moving violations ≤3 years). SDA driving performance (Error Score) was based on driving safety measures derived from simulator and eye-tracking data. Negative driving outcomes included simulated collisions or run-off-the-road incidents. A professional driving evaluator/instructor reviewed videos of SDA performance (DEI Score). Results The SDA demonstrated construct validity: 1.) Teens had a higher Error Score than adults (30 vs. 13, p=0.02); 2.) For each additional error committed, the relative risk of a participant's propensity for a simulated negative driving outcome increased by 8% (95% CI: 1.05–1.10, p<0.01). The SDA demonstrated criterion validity: Error Score was correlated with DEI Score (r=−0.66, p<0.001). Conclusions This study supports the concept of validated simulated driving tests like the SDA to assess novice driver skill in complex and hazardous driving scenarios. The SDA, as a standard protocol to evaluate teen driver performance, has the potential to facilitate screening and assessment of teen driving readiness and could be used to guide targeted skill training. PMID:25740939

  8. Driving performance under alcohol in simulated representative driving tasks: an alcohol calibration study for impairments related to medicinal drugs.

    PubMed

    Kenntner-Mabiala, Ramona; Kaussner, Yvonne; Jagiellowicz-Kaufmann, Monika; Hoffmann, Sonja; Krüger, Hans-Peter

    2015-04-01

    Comparing drug-induced driving impairments with the effects of benchmark blood alcohol concentrations (BACs) is an approved approach to determine the clinical relevance of findings for traffic safety. The present study aimed to collect alcohol calibration data to validate findings of clinical trials that were derived from a representative test course in a dynamic driving simulator. The driving performance of 24 healthy volunteers under placebo and with 0.05% and 0.08% BACs was measured in a double-blind, randomized, crossover design. Trained investigators assessed the subjects' driving performance and registered their driving errors. Various driving parameters that were recorded during the simulation were also analyzed. Generally, the participants performed worse on the test course (P < 0.05 for the investigators' assessment) under the influence of alcohol. Consistent with the relevant literature, lane-keeping performance parameters were sensitive to the investigated BACs. There were significant differences between the alcohol and placebo conditions in most of the parameters analyzed. However, the total number of errors was the only parameter discriminating significantly between all three BAC conditions. In conclusion, data show that the present experimental setup is suitable for future psychopharmacological research. Thereby, for each drug to be investigated, we recommend to assess a profile of various parameters that address different levels of driving. On the basis of this performance profile, the total number of driving errors is recommended as the primary endpoint. However, this overall endpoint should be completed by a specifically sensitive parameter that is chosen depending on the effect known to be induced by the tested drug.

  9. Adapting a Driving Simulator to Study Pedestrians' Street-Crossing Decisions: A Feasibility Study.

    PubMed

    Jäger, M; Nyffeler, T; Müri, R; Mosimann, U P; Nef, T

    2015-01-01

    The decision when to cross a street safely is a challenging task that poses high demands on perception and cognition. Both can be affected by normal aging, neurodegenerative disorder, and brain injury, and there is an increasing interest in studying street-crossing decisions. In this article, we describe how driving simulators can be modified to study pedestrians' street-crossing decisions. The driving simulator's projection system and the virtual driving environment were used to present street-crossing scenarios to the participants. New sensors were added to measure when the test person starts to cross the street. Outcome measures were feasibility, usability, task performance, and visual exploration behavior, and were measured in 15 younger persons, 15 older persons, and 5 post-stroke patients. The experiments showed that the test is feasible and usable, and the selected difficulty level was appropriate. Significant differences in the number of crashes between young participants and patients (p = .001) as well as between healthy older participants and patients (p = .003) were found. When the approaching vehicle's speed is high, significant differences between younger and older participants were found as well (p = .038). Overall, the new test setup was well accepted, and we demonstrated that driving simulators can be used to study pedestrians' street-crossing decisions.

  10. Objective assessment of the effects of texting while driving: a simulator study.

    PubMed

    Bendak, Salaheddine

    2015-01-01

    Recent advances in electronic communication technology led to many drivers opting to send and receive text messages while driving. This, inevitably, has a potential to distract drivers, impair driving performance and lead to crashes. This study aims to assess the risk involved in texting while driving through assessing the distraction caused and determining the change in key driving performance indicators. Twenty-one paid young male volunteers were recruited to participate in this study. Each participant drove a driving simulator on four different scenarios involving driving while texting and without texting on highways and town roads. Results showed that texting while driving led, on average, to five times more crashes than driving without texting. Due to distraction also, participants unnecessarily crossed lane boundaries and road boundaries more often while texting as compared to driving without texting. Moreover, distraction due to texting led to participants deviating their eyes off the road while texting 15 times per session, on average, more than without texting. Results demonstrated a high-risk level of distraction and clear impairment in drivers' ability to drive safely due to texting. Based on the results, practical recommendations to combat this phenomenon are given.

  11. A simulator study of the effects of singing on driving performance.

    PubMed

    Hughes, Genevieve M; Rudin-Brown, Christina M; Young, Kristie L

    2013-01-01

    This study aimed to investigate how singing while driving affects driver performance. Twenty-one participants completed three trials of a simulated drive concurrently while performing a peripheral detection task (PDT); each trial was conducted either without music, with participants listening to music, or with participants singing along to music. It was hypothesised that driving performance and PDT response times would be impaired, and that driver subjective workload ratings would be higher, when participants were singing to music compared to when there was no music or when participants were listening to music. As expected, singing while driving was rated as more mentally demanding, and resulted in slower and more variable speeds, than driving without music. Listening to music was associated with the slowest speeds overall, and fewer lane excursions than the no music condition. Interestingly, both music conditions were associated with slower speed-adjusted PDT response times and significantly less deviation within the lane than was driving without music. Collectively, results suggest that singing while driving alters driving performance and impairs hazard perception while at the same time increasing subjective mental workload. However, singing while driving does not appear to affect driving performance more than simply listening to music. Further, drivers' efforts to compensate for the increased mental workload associated with singing and listening to music by slowing down appear to be insufficient, as evidenced by relative increases in PDT response times in these two conditions compared to baseline. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. The influence of cruise control and adaptive cruise control on driving behaviour--a driving simulator study.

    PubMed

    Markvollrath; Schleicher, Susanne; Gelau, Christhard

    2011-05-01

    Although Cruise Control (CC) is available for most cars, no studies have been found which examine how this automation system influences driving behaviour. However, a relatively large number of studies have examined Adaptive Cruise Control (ACC) which compared to CC includes also a distance control. Besides positive effects with regard to a better compliance to speed limits, there are also indications of smaller distances to lead vehicles and slower responses in situations that require immediate braking. Similar effects can be expected for CC as this system takes over longitudinal control as well. To test this hypothesis, a simulator study was conducted at the German Aerospace Center (DLR). Twenty-two participants drove different routes (highway and motorway) under three different conditions (assisted by ACC, CC and manual driving without any system). Different driving scenarios were examined including a secondary task condition. On the one hand, both systems lead to lower maximum velocities and less speed limit violations. There was no indication that drivers shift more of their attention towards secondary tasks when driving with CC or ACC. However, there were delayed driver reactions in critical situations, e.g., in a narrow curve or a fog bank. These results give rise to some caution regarding the safety effects of these systems, especially if in the future their range of functionality (e.g., ACC Stop-and-Go) is further increased.

  13. Post and during event effect of cell phone talking and texting on driving performance--a driving simulator study.

    PubMed

    Thapa, Raju; Codjoe, Julius; Ishak, Sherif; McCarter, Kevin S

    2015-01-01

    A number of studies have been done in the field of driver distraction, specifically on the use of cell phone for either conversation or texting while driving. Researchers have focused on the driving performance of drivers when they were actually engaged in the task; that is, during the texting or phone conversation event. However, it is still unknown whether the impact of cell phone usages ceases immediately after the end of task. The primary objective of this article is to analyze the post-event effect of cell phone usage (texting and conversation) in order to verify whether the distracting effect lingers after the actual event has ceased. This study utilizes a driving simulator study of 36 participants to test whether a significant decrease in driver performance occurs during cell phone usage and after usage. Surrogate measures used to represent lateral and longitudinal control of the vehicle were standard deviation (SD) of lane position and mean velocity, respectively. RESULTS suggest that there was no significant decrease in driver performance (both lateral and longitudinal control) during and after the cell phone conversation. For the texting event, there were significant decreases in driver performance in both the longitudinal and lateral control of the vehicle during the actual texting task. The diminished longitudinal control ceased immediately after the texting event but the diminished lateral control lingered for an average of 3.38 s. The number of text messages exchanged did not affect the magnitude or duration of the diminished lateral control. The result indicates that the distraction and subsequent elevated crash risk of texting while driving linger even after the texting event has ceased. This finding has safety and policy implications in reducing distracted driving.

  14. Alcohol Dose Effects on Brain Circuits During Simulated Driving: An fMRI Study

    PubMed Central

    Meda, Shashwath A.; Calhoun, Vince D.; Astur, Robert S.; Turner, Beth M.; Ruopp, Kathryn; Pearlson, Godfrey D.

    2009-01-01

    Driving while intoxicated remains a major public health hazard. Driving is a complex task involving simultaneous recruitment of multiple cognitive functions. The investigators studied the neural substrates of driving and their response to different blood alcohol concentrations (BACs), using functional magnetic resonance imaging (fMRI) and a virtual reality driving simulator. We used independent component analysis (ICA) to isolate spatially independent and temporally correlated driving-related brain circuits in 40 healthy, adult moderate social drinkers. Each subject received three individualized, separate single-blind doses of beverage alcohol to produce BACs of 0.05% (moderate), 0.10% (high), or 0% (placebo). 3 T fMRI scanning and continuous behavioral measurement occurred during simulated driving. Brain function was assessed and compared using both ICA and a conventional general linear model (GLM) analysis. ICA results replicated and significantly extended our previous 1.5T study (Calhoun et al. [2004a]: Neuropsychopharmacology 29:2097–2017). GLM analysis revealed significant dose-related functional differences, complementing ICA data. Driving behaviors including opposite white line crossings and mean speed independently demonstrated significant dose-dependent changes. Behavior-based factors also predicted a frontal-basal-temporal circuit to be functionally impaired with alcohol dosage across baseline scaled, good versus poorly performing drivers. We report neural correlates of driving behavior and found dose-related spatio-temporal disruptions in critical driving-associated regions including the superior, middle and orbito frontal gyri, anterior cingulate, primary/supplementary motor areas, basal ganglia, and cerebellum. Overall, results suggest that alcohol (especially at high doses) causes significant impairment of both driving behavior and brain functionality related to motor planning and control, goal directedness, error monitoring, and memory. PMID

  15. Attentional demand and processing of relevant visual information during simulated driving: a MEG study.

    PubMed

    Fort, Alexandra; Martin, Robert; Jacquet-Andrieu, Armelle; Combe-Pangaud, Chantal; Foliot, Gérald; Daligault, Sébastien; Delpuech, Claude

    2010-12-02

    It is a well-known fact that attention is crucial for driving a car. This innovative study aims to assess the impact of attentional workload modulation on cerebral activity during a simulated driving task using magnetoencephalography (MEG). A car simulator equipped with a steering wheel, turn indicators, an accelerator and a brake pedal has been specifically designed to be used with MEG. Attentional demand has been modulated using a radio broadcast. During half of the driving scenarios, subjects could ignore the broadcast (simple task, ST) and during the other half, they had to actively listen to it in order to answer 3 questions (dual task, DT). Evoked magnetic responses were computed in both conditions separately for two visual stimuli of interest: traffic lights (from green to amber) and direction signs (arrows to the right or to the left) shown on boards. The cortical sources of these activities have been estimated using a minimum-norm current estimates modeling technique. Results show the activation of a large distributed network similar in ST and DT and similar for both the traffic lights and the direction signs. This network mainly involves sensory visual areas as well as parietal and frontal regions known to play a role in selective attention and motor areas. The increase of attentional demand affects the neuronal processing of relevant visual information for driving, as early as the perceptual stage. By demonstrating the feasibility of recording MEG activity during an interactive simulated driving task, this study opens new possibilities for investigating issues regarding drivers' activity.

  16. Designing simulator tools for rail research: the case study of a train driving microworld.

    PubMed

    Naweed, A; Hockey, G R J; Clarke, S D

    2013-05-01

    The microworld simulator paradigm is well established in the areas of ship-navigation and spaceflight, but has yet to be applied to rail. This paper presents a case study aiming to address this research gap, and describes the development of a train driving microworld as a tool to overcome some common research barriers. A theoretical framework for microworld design is tested and used to explore some key methodological issues and characteristics of train driving, enhancing theory development and providing a useful guideline for the designers of other collision-avoidance systems. A detailed description is given of the ATREIDES (Adaptive Train Research Enhanced Information Display & Environment Simulator) microworld, which simulates the work environment of a train driver in a high-speed passenger train. General indications of the testable driving scenarios that may be simulated are given, and an example of an ATREIDES-based study is presented to illustrate its applied research potential. The article concludes with a review of the design process, considers some strengths and limitations, and explores some future initiatives towards enhancing the systematic study of rail research in the human factors community.

  17. A Prospective Study of Loss of Consciousness in Epilepsy Using Virtual Reality Driving Simulation and Other Video Games

    PubMed Central

    Yang, Li; Morland, Thomas B.; Schmits, Kristen; Rawson, Elizabeth; Narasimhan, Poojitha; Motelow, Joshua E.; Purcaro, Michael J.; Peng, Kathy; Raouf, Saned; DeSalvo, Matthew N.; Oh, Taemin; Wilkerson, Jerome; Bod, Jessica; Srinivasan, Aditya; Kurashvili, Pimen; Anaya, Joseph; Manza, Peter; Danielson, Nathan; Ransom, Christopher B.; Huh, Linda; Elrich, Susan; Padin-Rosado, Jose; Naidu, Yamini; Detyniecki, Kamil; Hamid, Hamada; Fattahi, Pooia; Astur, Robert; Xiao, Bo; Duckrow, Robert B.; Blumenfeld, Hal

    2010-01-01

    Patients with epilepsy are at risk of traffic accidents when they have seizures while driving. However, driving is an essential part of normal daily life in many communities, and depriving patients of driving privileges can have profound consequences for their economic and social well being. In the current study, we collected ictal performance data from a driving simulator and two other video games in patients undergoing continuous video/EEG monitoring. We captured 22 seizures in 13 patients and found that driving impairment during seizures differed both in terms of magnitude and character, depending on the seizure type. Our study documents the feasibility of the prospective study of driving and other behaviors during seizures through the use of computer-based tasks. This methodology may be applied to further describe differential driving impairment in specific types of seizures and to gain data on anatomical networks disrupted in seizures that impair consciousness and driving safety. PMID:20537593

  18. A prospective study of loss of consciousness in epilepsy using virtual reality driving simulation and other video games.

    PubMed

    Yang, Li; Morland, Thomas B; Schmits, Kristen; Rawson, Elizabeth; Narasimhan, Poojitha; Motelow, Joshua E; Purcaro, Michael J; Peng, Kathy; Raouf, Saned; Desalvo, Matthew N; Oh, Taemin; Wilkerson, Jerome; Bod, Jessica; Srinivasan, Aditya; Kurashvili, Pimen; Anaya, Joseph; Manza, Peter; Danielson, Nathan; Ransom, Christopher B; Huh, Linda; Elrich, Susan; Padin-Rosado, Jose; Naidu, Yamini; Detyniecki, Kamil; Hamid, Hamada; Farooque, Pue; Astur, Robert; Xiao, Bo; Duckrow, Robert B; Blumenfeld, Hal

    2010-07-01

    Patients with epilepsy are at risk of traffic accidents when they have seizures while driving. However, driving is an essential part of normal daily life in many communities, and depriving patients of driving privileges can have profound consequences for their economic and social well-being. In the current study, we collected ictal performance data from a driving simulator and two other video games in patients undergoing continuous video/EEG monitoring. We captured 22 seizures in 13 patients and found that driving impairment during seizures differed in terms of both magnitude and character, depending on the seizure type. Our study documents the feasibility of a prospective study of driving and other behaviors during seizures through the use of computer-based tasks. This methodology may be applied to further describe differential driving impairment in specific types of seizures and to gain data on anatomical networks disrupted in seizures that impair consciousness and driving safety. Copyright 2010 Elsevier Inc. All rights reserved.

  19. Games for Traffic Education: An Experimental Study of a Game-Based Driving Simulator

    ERIC Educational Resources Information Center

    Backlund, Per; Engstrom, Henrik; Johannesson, Mikael; Lebram, Mikael

    2010-01-01

    In this article, the authors report on the construction and evaluation of a game-based driving simulator using a real car as a joystick. The simulator is constructed from off-the-shelf hardware and the simulation runs on open-source software. The feasibility of the simulator as a learning tool has been experimentally evaluated. Results are…

  20. Games for Traffic Education: An Experimental Study of a Game-Based Driving Simulator

    ERIC Educational Resources Information Center

    Backlund, Per; Engstrom, Henrik; Johannesson, Mikael; Lebram, Mikael

    2010-01-01

    In this article, the authors report on the construction and evaluation of a game-based driving simulator using a real car as a joystick. The simulator is constructed from off-the-shelf hardware and the simulation runs on open-source software. The feasibility of the simulator as a learning tool has been experimentally evaluated. Results are…

  1. Do Advance Yield Markings Increase Safe Driver Behaviors at Unsignalized, Marked Midblock Crosswalks? Driving Simulator Study

    PubMed Central

    Gómez, Radhameris A.; Samuel, Siby; Gerardino, Luis Roman; Romoser, Matthew R. E.; Collura, John; Knodler, Michael; Fisher, Donald L.

    2012-01-01

    In the United States, 78% of pedestrian crashes occur at noninter-section crossings. As a result, unsignalized, marked midblock crosswalks are prime targets for remediation. Many of these crashes occur under sight-limited conditions in which the view of critical information by the driver or pedestrian is obstructed by a vehicle stopped in an adjacent travel or parking lane on the near side of the crosswalk. Study of such a situation on the open road is much too risky, but study of the situation in a driving simulator is not. This paper describes the development of scenarios with sight limitations to compare potential vehicle–pedestrian conflicts on a driving simulator under conditions with two different types of pavement markings. Under the first condition, advance yield markings and symbol signs (prompts) that indicated “yield here to pedestrians” were used to warn drivers of pedestrians at marked, midblock crosswalks. Under the second condition, standard crosswalk treatments and prompts were used to warn drivers of these hazards. Actual crashes as well as the drivers' point of gaze were measured to determine if the drivers approaching a marked midblock crosswalk looked for pedestrians in the crosswalk more frequently and sooner in high-risk scenarios when advance yield markings and prompts were present than when standard markings and prompts were used. Fewer crashes were found to occur with advance yield markings. Drivers were also found to look for pedestrians much more frequently and much sooner with advance yield markings. The advantages and limitations of the use of driving simulation to study problems such as these are discussed. PMID:23082040

  2. Do Advance Yield Markings Increase Safe Driver Behaviors at Unsignalized, Marked Midblock Crosswalks? Driving Simulator Study.

    PubMed

    Gómez, Radhameris A; Samuel, Siby; Gerardino, Luis Roman; Romoser, Matthew R E; Collura, John; Knodler, Michael; Fisher, Donald L

    2011-01-01

    In the United States, 78% of pedestrian crashes occur at noninter-section crossings. As a result, unsignalized, marked midblock crosswalks are prime targets for remediation. Many of these crashes occur under sight-limited conditions in which the view of critical information by the driver or pedestrian is obstructed by a vehicle stopped in an adjacent travel or parking lane on the near side of the crosswalk. Study of such a situation on the open road is much too risky, but study of the situation in a driving simulator is not. This paper describes the development of scenarios with sight limitations to compare potential vehicle-pedestrian conflicts on a driving simulator under conditions with two different types of pavement markings. Under the first condition, advance yield markings and symbol signs (prompts) that indicated "yield here to pedestrians" were used to warn drivers of pedestrians at marked, midblock crosswalks. Under the second condition, standard crosswalk treatments and prompts were used to warn drivers of these hazards. Actual crashes as well as the drivers' point of gaze were measured to determine if the drivers approaching a marked midblock crosswalk looked for pedestrians in the crosswalk more frequently and sooner in high-risk scenarios when advance yield markings and prompts were present than when standard markings and prompts were used. Fewer crashes were found to occur with advance yield markings. Drivers were also found to look for pedestrians much more frequently and much sooner with advance yield markings. The advantages and limitations of the use of driving simulation to study problems such as these are discussed.

  3. Evaluation Research of the Effects of Longitudinal Speed Reduction Markings on Driving Behavior: A Driving Simulator Study.

    PubMed

    Ding, Han; Zhao, Xiaohua; Ma, Jianming; Rong, Jian

    2016-11-23

    The objective of this paper is to explore the effects of longitudinal speed reduction markings (LSRMs) on vehicle maneuvering and drivers' operation performance on interchange connectors with different radii. Empirical data were collected in a driving simulator. Indicators-relative speed change, standard deviation of acceleration, and gas/brake pedal power-were proposed to characterize driving behavior. Statistical results revealed that LSRMs could reduce vehicles' travel speed and limit drivers' willingness to increase speed in the entire connector. To probe the impacts of LSRMs, the connecter was split into four even sections. Effects of LSRMs on driving behavior were stronger in the second and the final sections of connectors. LSRMs also enhanced drivers' adaptability in the first three quarters of a connector when the radius was 50 m. Drivers' gas pedal operation would be impacted by LSRMs in the entire connector when the radius was 50 m. LSRMs could only make drivers press brake pedal more frequently in the second section with 80 m and 100 m radius. In the second quarter section of a connector-from the FQP (the first quartile point) to the MC (the middle point of curve)-LSRMs have better effects on influencing vehicle maneuvering and drivers' operation performance.

  4. Evaluation Research of the Effects of Longitudinal Speed Reduction Markings on Driving Behavior: A Driving Simulator Study

    PubMed Central

    Ding, Han; Zhao, Xiaohua; Ma, Jianming; Rong, Jian

    2016-01-01

    The objective of this paper is to explore the effects of longitudinal speed reduction markings (LSRMs) on vehicle maneuvering and drivers’ operation performance on interchange connectors with different radii. Empirical data were collected in a driving simulator. Indicators—relative speed change, standard deviation of acceleration, and gas/brake pedal power—were proposed to characterize driving behavior. Statistical results revealed that LSRMs could reduce vehicles’ travel speed and limit drivers’ willingness to increase speed in the entire connector. To probe the impacts of LSRMs, the connecter was split into four even sections. Effects of LSRMs on driving behavior were stronger in the second and the final sections of connectors. LSRMs also enhanced drivers’ adaptability in the first three quarters of a connector when the radius was 50 m. Drivers’ gas pedal operation would be impacted by LSRMs in the entire connector when the radius was 50 m. LSRMs could only make drivers press brake pedal more frequently in the second section with 80 m and 100 m radius. In the second quarter section of a connector—from the FQP (the first quartile point) to the MC (the middle point of curve)—LSRMs have better effects on influencing vehicle maneuvering and drivers’ operation performance. PMID:27886107

  5. Driver behaviours on rural highways with and without curbs - a driving simulator based study.

    PubMed

    Yang, Qiang; Overton, Ryan; Han, Lee D; Yan, Xuedong; Richards, Stephen H

    2014-01-01

    The speed limit of 55 mph (88 km/h) is used typically on rural highways in the U.S. When curbs are installed, a lower speed limit is suggested because running into curbs at high speeds may cause significant vehicular damage and severe injuries. However, it has been argued that lowering the speed limit may cause confusion in drivers, who do not perceive the risk and tend to operate their vehicles at the same speed as before. To better understand driver behaviour on two-lane rural highways before and after curb installation, the authors conducted a series of experiments on a high-fidelity driving simulator in different posted speed limit, curb installation, lateral curb clearance, weather, visibility, and traffic conditions. Results of the study suggest that driver behaviours are influenced by the various factors in a complex and interrelated manner. It is likely that curbs have no influence on a driver's selection of speed. Drivers do perceive the risk from the curb or the opposing traffic when selecting their lane positions. The available space between the curb and the opposing traffic is crucial and has significant effects on driving behaviours. The subjective effects of drivers are found to be influential to driving behaviours.

  6. Effects of fatigue on driving performance under different roadway geometries: a simulator study.

    PubMed

    Du, Hongji; Zhao, Xiaohua; Zhang, Xingjian; Zhang, Yunlong; Rong, Jian

    2015-01-01

    This article examines the effects of fatigue on driving performance under different roadway geometries using a driving simulator. Twenty-four participants each completed a driving scenario twice: while alert and while experiencing fatigue. The driving scenario was composed of straight road segments and curves; there were 6 curves with 3 radius values (i.e., 200, 500, and 800 m) and 2 turning directions (i.e., left and right). Analysis was conducted on driving performance measures such as longitudinal speed, steering wheel movements, and lateral position. RESULTS confirmed that decremental changes in driving performance due to fatigue varied among road conditions. On straight segments, drivers' abilities to steer and maintain lane position were impaired, whereas on curves we found decremental changes in the quality of longitudinal speed as well as steering control and keeping the vehicle in the lane. Moreover, the effects of fatigue on driving performance were relative to the radius and direction of the curve. Fatigue impaired drivers' abilities to control the steering wheel, and the impairment proved more obvious on curves. The degree varied significantly as the curve radius changed. Drivers tended to drive closer to the right side due to fatigue, and the impairment in maintaining lane position became more obvious as the right-turn curve radius decreased. Driver fatigue has detrimental effects on driving performance, and the effects differ under different roadway geometries.

  7. Do mental workload and presence experienced when driving a real car predispose drivers to simulator sickness? An exploratory study.

    PubMed

    Milleville-Pennel, Isabelle; Charron, Camilo

    2015-01-01

    This study is aimed at determining whether the simulator sickness (SS) experienced by some drivers is influenced by psychological factors, such as cognitive solicitation, affective factors and a feeling of presence. We also wished to determine whether SS is caused by an individual reaction to the virtual environment (VE) itself or can be attributed to a more general personal predisposition. For this reason, we considered three conditions: driving a simulator, driving one's own vehicle and driving a school-owned vehicle. Fourteen expert drivers participated in the study. Each drove under a different experimental condition and then responded to various questionnaires (SSQ, NASA-TLX and QPF). Our results showed that it is possible to identify at least three sources of explanation of why some people are more liable to feel sick in a driving simulator. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Relationships between driving simulator performance and driving test results.

    PubMed

    de Winter, J C F; de Groot, S; Mulder, M; Wieringa, P A; Dankelman, J; Mulder, J A

    2009-02-01

    This article is considered relevant because: 1) car driving is an everyday and safety-critical task; 2) simulators are used to an increasing extent for driver training (related topics: training, virtual reality, human-machine interaction); 3) the article addresses relationships between performance in the simulator and driving test results--a relevant topic for those involved in driver training and the virtual reality industries; 4) this article provides new insights about individual differences in young drivers' behaviour. Simulators are being used to an increasing extent for driver training, allowing for the possibility of collecting objective data on driver proficiency under standardised conditions. However, relatively little is known about how learner drivers' simulator measures relate to on-road driving. This study proposes a theoretical framework that quantifies driver proficiency in terms of speed of task execution, violations and errors. This study investigated the relationships between these three measures of learner drivers' (n=804) proficiency during initial simulation-based training and the result of the driving test on the road, occurring an average of 6 months later. A higher chance of passing the driving test the first time was associated with making fewer steering errors on the simulator and could be predicted in regression analysis with a correlation of 0.18. Additionally, in accordance with the theoretical framework, a shorter duration of on-road training corresponded with faster task execution, fewer violations and fewer steering errors (predictive correlation 0.45). It is recommended that researchers conduct more large-scale studies into the reliability and validity of simulator measures and on-road driving tests.

  9. Modeling the influence of Chevron alignment sign on young male driver performance: A driving simulator study.

    PubMed

    Wu, Yiping; Zhao, Xiaohua; Chen, Chen; He, Jiayuan; Rong, Jian; Ma, Jianming

    2016-10-01

    In China, the Chevron alignment sign on highways is a vertical rectangle with a white arrow and border on a blue background, which differs from its counterpart in other countries. Moreover, little research has been devoted to the effectiveness of China's Chevron signs; there is still no practical method to quantitatively describe the impact of Chevron signs on driver performance in roadway curves. In this paper, a driving simulator experiment collected data on the driving performance of 30 young male drivers as they navigated on 29 different horizontal curves under different conditions (presence of Chevron signs, curve radius and curve direction). To address the heterogeneity issue in the data, three models were estimated and tested: a pooled data linear regression model, a fixed effects model, and a random effects model. According to the Hausman Test and Akaike Information Criterion (AIC), the random effects model offers the best fit. The current study explores the relationship between driver performance (i.e., vehicle speed and lane position) and horizontal curves with respect to the horizontal curvature, presence of Chevron signs, and curve direction. This study lays a foundation for developing procedures and guidelines that would allow more uniform and efficient deployment of Chevron signs on China's highways. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Assessing Risk-Taking in a Driving Simulator Study: Modeling Longitudinal Semi-Continuous Driving Data Using a Two-Part Regression Model with Correlated Random Effects.

    PubMed

    Tran, Van; Liu, Danping; Pradhan, Anuj K; Li, Kaigang; Bingham, C Raymond; Simons-Morton, Bruce G; Albert, Paul S

    2015-01-01

    Signalized intersection management is a common measure of risky driving in simulator studies. In a recent randomized trial, investigators were interested in whether teenage males exposed to a risk-accepting passenger took more intersection risks in a driving simulator compared with those exposed to a risk-averse peer passenger. Analyses in this trial are complicated by the longitudinal or repeated measures that are semi-continuous with clumping at zero. Specifically, the dependent variable in a randomized trial looking at the effect of risk-accepting versus risk-averse peer passengers on teenage simulator driving is comprised of two components. The discrete component measures whether the teen driver stops for a yellow light, and the continuous component measures the time the teen driver, who does not stop, spends in the intersection during a red light. To convey both components of this measure, we apply a two-part regression with correlated random effects model (CREM), consisting of a logistic regression to model whether the driver stops for a yellow light and a linear regression to model the time spent in the intersection during a red light. These two components are related through the correlation of their random effects. Using this novel analysis, we found that those exposed to a risk-averse passenger have a higher proportion of stopping at yellow lights and a longer mean time in the intersection during a red light when they did not stop at the light compared to those exposed to a risk-accepting passenger, consistent with the study hypotheses and previous analyses. Examining the statistical properties of the CREM approach through simulations, we found that in most situations, the CREM achieves greater power than competing approaches. We also examined whether the treatment effect changes across the length of the drive and provided a sample size recommendation for detecting such phenomenon in subsequent trials. Our findings suggest that CREM provides an efficient

  11. Does haptic steering guidance instigate speeding? A driving simulator study into causes and remedies.

    PubMed

    Melman, T; de Winter, J C F; Abbink, D A

    2017-01-01

    An important issue in road traffic safety is that drivers show adverse behavioral adaptation (BA) to driver assistance systems. Haptic steering guidance is an upcoming assistance system which facilitates lane-keeping performance while keeping drivers in the loop, and which may be particularly prone to BA. Thus far, experiments on haptic steering guidance have measured driver performance while the vehicle speed was kept constant. The aim of the present driving simulator study was to examine whether haptic steering guidance causes BA in the form of speeding, and to evaluate two types of haptic steering guidance designed not to suffer from BA. Twenty-four participants drove a 1.8m wide car for 13.9km on a curved road, with cones demarcating a single 2.2m narrow lane. Participants completed four conditions in a counterbalanced design: no guidance (Manual), continuous haptic guidance (Cont), continuous guidance that linearly reduced feedback gains from full guidance at 125km/h towards manual control at 130km/h and above (ContRF), and haptic guidance provided only when the predicted lateral position was outside a lateral bandwidth (Band). Participants were familiarized with each condition prior to the experimental runs and were instructed to drive as they normally would while minimizing the number of cone hits. Compared to Manual, the Cont condition yielded a significantly higher driving speed (on average by 7km/h), whereas ContRF and Band did not. All three guidance conditions yielded better lane-keeping performance than Manual, whereas Cont and ContRF yielded lower self-reported workload than Manual. In conclusion, continuous steering guidance entices drivers to increase their speed, thereby diminishing its potential safety benefits. It is possible to prevent BA while retaining safety benefits by making a design adjustment either in lateral (Band) or in longitudinal (ContRF) direction.

  12. Using virtual reality to study alcohol intoxication effects on the neural correlates of simulated driving.

    PubMed

    Calhoun, V D; Carvalho, K; Astur, R; Pearlson, G D

    2005-09-01

    The use of virtual reality in the form of simulated tasks can provide a realistic environment in which to study complex naturalistic behaviors. Many of the behavioral effects of alcohol intoxication are well known, but there is relatively little imaging evidence examining how alcohol exposure might transiently modulate brain function, especially in the context of task performance. In this review, we provide a brief synopsis of previous work using functional magnetic resonance imaging (fMRI) to study the neural correlates of alcohol intoxication. We describe in detail two studies from our published work, the first involving a visual perception paradigm, and the second involving virtual reality through a naturalistic behavior; simulated driving. Participants received single-blind individualized doses of beverage alcohol designed to produce blood alcohol content (BAC) of 0.04 and 0.08 or placebo. Subjects were fMRI scanned after training to asymptote performance. In both studies we found specific circuits that were differentially modulated by alcohol, we revealed both global and local effects of alcohol, and we examined relationships between behavior, brain function, and alcohol blood levels.

  13. Effects of Lane Width, Lane Position and Edge Shoulder Width on Driving Behavior in Underground Urban Expressways: A Driving Simulator Study

    PubMed Central

    Liu, Shuo; Wang, Junhua; Fu, Ting

    2016-01-01

    This study tested the effects of lane width, lane position and edge shoulder width on driving behavior for a three-lane underground urban expressway. A driving simulator was used with 24 volunteer test subjects. Five lane widths (2.85, 3.00, 3.25, 3.50, and 3.75 m) and three shoulder widths (0.50, 0.75, and 1.00 m) were studied. Driving speed, lane deviation and subjective perception of driving behavior were collected as performance measures. The results show that lane and shoulder width have significant effects on driving speed. Average driving speed increases from 60.01 km/h in the narrowest lane to 88.05 km/h in the widest lane. While both narrower lanes and shoulders result in reduced speed and lateral lane deviation, the effect of lane width is greater than that of shoulder width. When the lane and shoulder are narrow, drivers in the left or right lane tend to shy away from the tunnel wall, even encroaching into the neighboring middle lane. As the lane or shoulder gets wider, drivers tend to stay in the middle of the lane. An interesting finding is that although few participants acknowledged that lane position had any great bearing on their driving behaviors, the observed driving speed is statistically higher in the left lane than in the other two lanes when the lane width is narrow (in 2.85, 3 and 3.25 m lanes). These findings provided support for amending the current design specifications of urban underground roads, such as the relationship between design speed and lane width, speed limit, and combination form of lanes. PMID:27754447

  14. Effects of Lane Width, Lane Position and Edge Shoulder Width on Driving Behavior in Underground Urban Expressways: A Driving Simulator Study.

    PubMed

    Liu, Shuo; Wang, Junhua; Fu, Ting

    2016-10-14

    This study tested the effects of lane width, lane position and edge shoulder width on driving behavior for a three-lane underground urban expressway. A driving simulator was used with 24 volunteer test subjects. Five lane widths (2.85, 3.00, 3.25, 3.50, and 3.75 m) and three shoulder widths (0.50, 0.75, and 1.00 m) were studied. Driving speed, lane deviation and subjective perception of driving behavior were collected as performance measures. The results show that lane and shoulder width have significant effects on driving speed. Average driving speed increases from 60.01 km/h in the narrowest lane to 88.05 km/h in the widest lane. While both narrower lanes and shoulders result in reduced speed and lateral lane deviation, the effect of lane width is greater than that of shoulder width. When the lane and shoulder are narrow, drivers in the left or right lane tend to shy away from the tunnel wall, even encroaching into the neighboring middle lane. As the lane or shoulder gets wider, drivers tend to stay in the middle of the lane. An interesting finding is that although few participants acknowledged that lane position had any great bearing on their driving behaviors, the observed driving speed is statistically higher in the left lane than in the other two lanes when the lane width is narrow (in 2.85, 3 and 3.25 m lanes). These findings provided support for amending the current design specifications of urban underground roads, such as the relationship between design speed and lane width, speed limit, and combination form of lanes.

  15. Driving performance in a power wheelchair simulator.

    PubMed

    Archambault, Philippe S; Tremblay, Stéphanie; Cachecho, Sarah; Routhier, François; Boissy, Patrick

    2012-05-01

    A power wheelchair simulator can allow users to safely experience various driving tasks. For such training to be efficient, it is important that driving performance be equivalent to that in a real wheelchair. This study aimed at comparing driving performance in a real and in a simulated environment. Two groups of healthy young adults performed different driving tasks, either in a real power wheelchair or in a simulator. Smoothness of joystick control as well as the time necessary to complete each task were recorded and compared between the two groups. Driving strategies were analysed from video recordings. The sense of presence, of really being in the virtual environment, was assessed through a questionnaire. Smoothness of joystick control was the same in the real and virtual groups. Task completion time was higher in the simulator for the more difficult tasks. Both groups showed similar strategies and difficulties. The simulator generated a good sense of presence, which is important for motivation. Performance was very similar for power wheelchair driving in the simulator or in real life. Thus, the simulator could potentially be used to complement training of individuals who require a power wheelchair and use a regular joystick. [Box: see text].

  16. The effect of three low-cost engineering treatments on driver fatigue: A driving simulator study.

    PubMed

    Merat, Natasha; Jamson, A Hamish

    2013-01-01

    Three engineering treatments were implemented in a driving simulator study to assess the effect of road-based measures on alleviating the symptoms of fatigue. Using results from previous research on the effect of circadian rhythms on fatigue-related crashes, two groups of male drivers were recruited for this study: young shift workers under the age of 35, who attended immediately after their night shift, and older drivers over the age of 45, who completed the study during the 'post lunch dip' period, after consuming lunch. Eye tracking (PERCLOS) and lateral driver performance measures were used to assess whether baseline measures of fatigue changed after drivers experienced each of the three treatments, which included variable message signs, chevrons and rumble strips. Results showed a marked difference in these measures between drivers' baseline (not fatigued) and experimental (fatigued) visits. There were also some reductions in lateral deviation and eye closure (as measured by PERCLOS) when the treatments were encountered, but no marked difference between the three treatments. These results suggest that in addition to driver- and vehicle-based methods currently employed to mitigate the effects of fatigue, the inclusion of such engineering measures may help alleviate fatigue-related impairments in driving, particularly if such treatments are implemented during long stretches of straight monotonous roads which are known to be associated with fatigue-related crashes. However, positive effects of the treatments were short lived, prompting the need for further investigations on their optimal frequency of presentation and combination to achieve maximum impact from these low-cost, road-based treatments.

  17. Complexation Enhancement Drives Water-to-Oil Ion Transport: A Simulation Study.

    PubMed

    Qiao, Baofu; Ferru, Geoffroy; Ellis, Ross J

    2017-01-05

    We address the structures and energetics of ion solvation in aqueous and organic solutions to understand liquid-liquid ion transport. Atomistic molecular dynamics (MD) simulations with polarizable force field are performed to study the coordination transformations driving lanthanide (Ln(III) ) and nitrate ion transport between aqueous and an alkylamide-oil solution. An enhancement of the coordination behavior in the organic phase is achieved in contrast with the aqueous solution. In particular, the coordination number of Ce(3+) increases from 8.9 in the aqueous to 9.9 in the organic solutions (from 8 in the aqueous to 8.8 in the organic systems for Yb(3+) ). Moreover, the local coordination environment changes dramatically. Potential of mean force calculations show that the Ln(III) -ligand coordination interaction strengths follow the order of Ln(III) -nitrate>Ln(III) -water>Ln(III) -DMDBTDMA. They increase 2-fold in the lipophilic environment in comparison to the aqueous phase, and we attribute this to the shedding of the outer solvation shell. Our findings highlight the importance of outer sphere interactions on the competitive solvation energetics that cause ions to migrate between immiscible phases; an essential ingredient for advancing important applications such as rare earth metal separations. Some open questions in simulating the coordination behavior of heavy metals are also addressed.

  18. Complexation Enhancement Drives Water-to-Oil Ion Transport: A Simulation Study

    SciTech Connect

    Qiao, Baofu; Ferru, Geoffroy; Ellis, Ross J.

    2016-11-23

    We address the structures and energetics of ion solvation in aqueous and organic solutions to understand liquid-liquid ion transport. Atomistic molecular dynamics (MD) simulations with polarizable force field are performed to study the coordination transformations driving lanthanide (Ln(III)) and nitrate ion transport between aqueous and an alkylamide-oil solution. An enhancement of the coordination behavior in the organic phase is achieved in contrast with the aqueous solution. In particular, the coordination number of Ce3+ increases from 8.9 in the aqueous to 9.9 in the organic solutions (from 8 in the aqueous to 8.8 in the organic systems for Yb3+). Moreover, the local coordination environ ment changes dramatically. Potential of mean force calculations show that the Ln(III)-ligand coordination interaction strengths follow the order of Ln(III-)nitrate> Ln(III)-water>Ln(III)-DMDBTDMA. They increase 2-fold in the lipophilic environment in comparison to the aqueous phase, and we attribute this to the shedding of the outer solvation shell. Our findings highlight the importance of outer sphere interactions on the competitive solvation energetics that cause ions to migrate between immiscible phases; an essential ingredient for advancing important applications such as rare earth metal separations. Some open questions in simulating the coordination behavior of heavy metals are also addressed.

  19. The effect of pavement markings on driving behaviour in curves: a simulator study.

    PubMed

    Ariën, Caroline; Brijs, Kris; Vanroelen, Giovanni; Ceulemans, Wesley; Jongen, Ellen M M; Daniels, Stijn; Brijs, Tom; Wets, Geert

    2017-05-01

    This study investigates the effect of two pavement markings (transverse rumble strips (TRS) and a backward pointing herringbone pattern (HP)) on speed and lateral control in and nearby curves. Two real-world curves with strong indications of a safety problem were replicated as realistic as possible in the simulator. Results show that both speed and lateral control differ between the curves. These behavioural differences are probably due to curve-related dissimilarities with respect to geometric alignment, cross-sectional design and speed limit. TRS and HP both influenced mean speed and mean acceleration/deceleration but not lateral control. TRS generated an earlier and more stable speed reduction than HP which induced significant speed reductions along the curve. The TRS gives drivers more time to generate the right expectations about the upcoming curve. When accidents occur primarily near the curve entry, TRS is recommended. The HP has the potential to reduce accidents at the curve end. Practitioner Summary: Two pavement markings (transversal rumble strips and HP) nearby dangerous curves were investigated in the driving simulator. TRS generated an earlier and more stable speed reduction than HP which induced speed reductions along the curve. The TRS gives drivers more time to generate right expectations about the upcoming curve.

  20. COLLISION AVOIDANCE TRAINING USING A DRIVING SIMULATOR IN DRIVERS WITH PARKINSON’S DISEASE: A PILOT STUDY

    PubMed Central

    Dawson, Jeffrey D.; Rizzo, Matthew; Anderson, Steven W.; Dastrup, Elizabeth; Uc, Ergun Y.

    2011-01-01

    Summary Parkinson’s disease (PD) impairs driving performance, and simulator studies have shown increased crashes compared to controls. In this pilot study, eight drivers with PD participated in three drive sessions with multiple simulator intersections of varying visibility and traffic load, where an incurring vehicle posed a crash risk. Over the course of the three sessions (once every 1–2 weeks), we observed reduction in crashes (p=0.059) and reaction times (p=0.006) to the vehicle incursion. These findings suggest that our simulator training program is feasible and potentially useful in drivers with PD. Future research questions include transfer of training to different driving tasks, duration of benefit, and the effect on long term real life outcomes in comparison to a standard intervention (e.g., driver education class) in a randomized trial. PMID:24273752

  1. Driving with Intuition: A Preregistered Study about the EEG Anticipation of Simulated Random Car Accidents

    PubMed Central

    Duma, Gian Marco; Mento, Giovanni; Manari, Tommaso; Martinelli, Massimiliano

    2017-01-01

    The study of neural pre-stimulus or “anticipatory” activity opened a new window for understanding how the brain actively constructs the forthcoming reality. Usually, experimental paradigms designed to study anticipatory activity make use of stimuli. The purpose of the present study is to expand the study of neural anticipatory activity upon the temporal occurrence of dichotomic, statistically unpredictable (random) stimuli within an ecological experimental paradigm. To this purpose, we used a simplified driving simulation including two possible, randomly-presented trial types: a car crash end trial and a no car crash end trial. Event Related Potentials (ERP) were extracted -3,000 ms before stimulus onset. We identified a fronto-central negativity starting around 1,000 ms before car crash presentation. By contrast, a whole-scalp distributed positivity characterized the anticipatory activity observed before the end of the trial in the no car crash end condition. The present data are in line with the hypothesis that the brain may also anticipate dichotomic, statistically unpredictable stimuli, relaying onto different pre-stimulus ERP activity. Possible integration with car-smart-systems is also suggested. PMID:28103303

  2. Driving with Intuition: A Preregistered Study about the EEG Anticipation of Simulated Random Car Accidents.

    PubMed

    Duma, Gian Marco; Mento, Giovanni; Manari, Tommaso; Martinelli, Massimiliano; Tressoldi, Patrizio

    2017-01-01

    The study of neural pre-stimulus or "anticipatory" activity opened a new window for understanding how the brain actively constructs the forthcoming reality. Usually, experimental paradigms designed to study anticipatory activity make use of stimuli. The purpose of the present study is to expand the study of neural anticipatory activity upon the temporal occurrence of dichotomic, statistically unpredictable (random) stimuli within an ecological experimental paradigm. To this purpose, we used a simplified driving simulation including two possible, randomly-presented trial types: a car crash end trial and a no car crash end trial. Event Related Potentials (ERP) were extracted -3,000 ms before stimulus onset. We identified a fronto-central negativity starting around 1,000 ms before car crash presentation. By contrast, a whole-scalp distributed positivity characterized the anticipatory activity observed before the end of the trial in the no car crash end condition. The present data are in line with the hypothesis that the brain may also anticipate dichotomic, statistically unpredictable stimuli, relaying onto different pre-stimulus ERP activity. Possible integration with car-smart-systems is also suggested.

  3. The influence of combined alignments on lateral acceleration on mountainous freeways: a driving simulator study.

    PubMed

    Wang, Xuesong; Wang, Ting; Tarko, Andrew; Tremont, Paul J

    2015-03-01

    Combined horizontal and vertical alignments are frequently used in mountainous freeways in China; however, design guidelines that consider the safety impact of combined alignments are not currently available. Past field studies have provided some data on the relationship between road alignment and safety, but the effects of differing combined alignments on either lateral acceleration or safety have not systematically examined. The primary reason for this void in past research is that most of the prior studies used observational methods that did not permit control of the key variables. A controlled parametric study is needed that examines lateral acceleration as drivers adjust their speeds across a range of combined horizontal and vertical alignments. Such a study was conducted in Tongji University's eight-degree-of-freedom driving simulator by replicating the full range of combined alignments used on a mountainous freeway in China. Multiple linear regression models were developed to estimate the effects of the combined alignments on lateral acceleration. Based on these models, domains were calculated to illustrate the results and to assist engineers to design safer mountainous freeways.

  4. Driving Performance Under Alcohol in Simulated Representative Driving Tasks

    PubMed Central

    Kenntner-Mabiala, Ramona; Kaussner, Yvonne; Jagiellowicz-Kaufmann, Monika; Hoffmann, Sonja; Krüger, Hans-Peter

    2015-01-01

    Abstract Comparing drug-induced driving impairments with the effects of benchmark blood alcohol concentrations (BACs) is an approved approach to determine the clinical relevance of findings for traffic safety. The present study aimed to collect alcohol calibration data to validate findings of clinical trials that were derived from a representative test course in a dynamic driving simulator. The driving performance of 24 healthy volunteers under placebo and with 0.05% and 0.08% BACs was measured in a double-blind, randomized, crossover design. Trained investigators assessed the subjects’ driving performance and registered their driving errors. Various driving parameters that were recorded during the simulation were also analyzed. Generally, the participants performed worse on the test course (P < 0.05 for the investigators’ assessment) under the influence of alcohol. Consistent with the relevant literature, lane-keeping performance parameters were sensitive to the investigated BACs. There were significant differences between the alcohol and placebo conditions in most of the parameters analyzed. However, the total number of errors was the only parameter discriminating significantly between all three BAC conditions. In conclusion, data show that the present experimental setup is suitable for future psychopharmacological research. Thereby, for each drug to be investigated, we recommend to assess a profile of various parameters that address different levels of driving. On the basis of this performance profile, the total number of driving errors is recommended as the primary endpoint. However, this overall endpoint should be completed by a specifically sensitive parameter that is chosen depending on the effect known to be induced by the tested drug. PMID:25689289

  5. The effect of male teenage passengers on male teenage drivers: findings from a driving simulator study

    PubMed Central

    Ouimet, Marie Claude; Pradhan, Anuj K.; Simons-Morton, Bruce G.; Divekar, Gautam; Mehranian, Hasmik; Fisher, Donald L.

    2014-01-01

    Studies have shown that teenage drivers are less attentive, more frequently exhibit risky driving behavior, and have a higher fatal crash risk in the presence of peers. The effects of direct peer pressure and conversation on young drivers have been examined. Little is known about the impact on driving performance of the presence of a non-interacting passenger and subtle modes of peer influence, such as perceived social norms. The goal of this study was to examine if teenagers would engage in more risky driving practices and be less attentive in the presence of a passenger (vs. driving alone) as well as with a risk-accepting (vs. risk-averse) passenger. A confederate portrayed the passenger's characteristics mainly by his non-verbal attitude. The relationship between driver characteristics and driving behavior in the presence of a passenger was also examined. Thirty-six male participants aged 16-17 years old were randomly assigned to drive with a risk-accepting or risk-averse passenger. Main outcomes included speed, headway, gap acceptance, eye glances at hazards, and horizontal eye movement. Driver characteristics such as tolerance of deviance, susceptibility to peer pressure, and self-esteem were measured. Compared to solo driving, the presence of a passenger was associated with significantly fewer eye glances at hazards and a trend for fewer horizontal eye movements. Contrary to the hypothesis, however, passenger presence was associated with a greater number of vehicles before initiating a left turn. Results also showed, contrary to the hypothesis, that participants with the risk-accepting passenger maintained significantly longer headway with the lead vehicle and engaged in more eye glances at hazards than participants with the risk-averse passenger. Finally, when driving with the passenger, earlier initiation of a left turn in a steady stream of oncoming vehicles was significantly associated with higher tolerance of deviance and susceptibility to peer pressure

  6. The effect of male teenage passengers on male teenage drivers: findings from a driving simulator study.

    PubMed

    Ouimet, Marie Claude; Pradhan, Anuj K; Simons-Morton, Bruce G; Divekar, Gautam; Mehranian, Hasmik; Fisher, Donald L

    2013-09-01

    Studies have shown that teenage drivers are less attentive, more frequently exhibit risky driving behavior, and have a higher fatal crash risk in the presence of peers. The effects of direct peer pressure and conversation on young drivers have been examined. Little is known about the impact on driving performance of the presence of a non-interacting passenger and subtle modes of peer influence, such as perceived social norms. The goal of this study was to examine if teenagers would engage in more risky driving practices and be less attentive in the presence of a passenger (vs. driving alone) as well as with a risk-accepting (vs. risk-averse) passenger. A confederate portrayed the passenger's characteristics mainly by his non-verbal attitude. The relationship between driver characteristics and driving behavior in the presence of a passenger was also examined. Thirty-six male participants aged 16-17 years old were randomly assigned to drive with a risk-accepting or risk-averse passenger. Main outcomes included speed, headway, gap acceptance, eye glances at hazards, and horizontal eye movement. Driver characteristics such as tolerance of deviance, susceptibility to peer pressure, and self-esteem were measured. Compared to solo driving, the presence of a passenger was associated with significantly fewer eye glances at hazards and a trend for fewer horizontal eye movements. Contrary to the hypothesis, however, Passenger Presence was associated with waiting for a greater number of vehicles to pass before initiating a left turn. Results also showed, contrary to the hypothesis, that participants with the risk-accepting passenger maintained significantly longer headway with the lead vehicle and engaged in more eye glances at hazards than participants with the risk-averse passenger. Finally, when driving with the passenger, earlier initiation of a left turn in a steady stream of oncoming vehicles was significantly associated with higher tolerance of deviance and

  7. The impact of perceptual treatments on driver's behavior: from driving simulator studies to field tests--first results.

    PubMed

    Auberlet, Jean-Michel; Rosey, Florence; Anceaux, Françoise; Aubin, Sébastien; Briand, Patrice; Pacaux, Marie-Pierre; Plainchault, Patrick

    2012-03-01

    Our study focused on the lateral position of drivers in relation to risk on rural crest vertical curves, using a field site proposed by a local operator of the French road network (Conseil Général de Maine-et-Loire, 49). The final goal was to test one road treatment on this field site. The study consisted of three stages. The first, using driving simulators, selected two perceptual treatments (i.e., rumble strips on both sides of the centerline and sealed shoulders) from five that were tested in order to help drivers maintain lateral control when driving on crest vertical curves. The rumble strips were installed first on the field site. The second stage was to develop a diagnostic device specifically in order to evaluate, on the field site, the impact of a perceptual treatment on the driver's performance (i.e., lateral position). This diagnostic device was installed in the field upstream and downstream of the target crest vertical curve. The third stage was to collect the data during two periods, before and after the centerline rumble strips were installed. We then compared the results obtained in the field study with those from the driving simulator studies. The comparison showed that, as in the simulator studies, the centerline rumble strips on the crest vertical curve affected lateral positions, causing the participants to drive closer to the center of the lane. Finally, the results showed the usefulness of driving simulators in the road design process. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Driving simulators for occupational therapy screening, assessment, and intervention.

    PubMed

    Classen, Sherrilene; Brooks, Johnell

    2014-04-01

    Simulation technology provides safe, objective, and repeatable performance measures pertaining to operational (e.g., avoiding a collision) or tactical (e.g., lane maintenance) driver behaviors. Many occupational therapy researchers and others are using driving simulators to test a variety of applications across diverse populations. A growing body of literature provides support for associations between simulated driving and actual on-road driving. One limitation of simulator technology is the occurrence of simulator sickness, but management strategies exist to curtail or mitigate its onset. Based on the literature review and a consensus process, five consensus statements are presented to support the use of driving simulation technology among occupational therapy practitioners. The evidence suggests that by using driving simulators occupational therapy practitioners may detect underlying impairments in driving performance, identify driving errors in at-risk drivers; differentiate between driving performance of impaired and healthy controls groups; show driving errors with absolute and relative validity compared to on-road studies; and mitigate the onset of simulator sickness. Much progress has been made among occupational therapy researchers and practitioners in the use of driving simulation technology; however, empirical support is needed to further justify the use of driving simulators in clinical practice settings as a valid, reliable, clinical useful, and cost effective tool for driving assessment and intervention.

  9. An investigation of the effects of the common cold on simulated driving performance and detection of collisions: a laboratory study

    PubMed Central

    Jamson, Samantha

    2012-01-01

    Objective The aim of the present research was to investigate whether individuals with a common cold showed impaired ability on a simulated driving task and the ability to detect potential collisions between moving objects. Design The study involved comparison of a healthy group with a group with colds. These scores were adjusted for individual differences by collecting further data when both groups were healthy and using these scores as covariates. On both occasions, volunteers rated their symptoms and carried out a simulated driving session. On the first occasion, volunteers also carried out a collision detection task. Setting University of Leeds Institute for Transport Studies. Sample Twenty-five students from the University of Leeds. Ten volunteers were healthy on both occasions and 15 had a cold on the first session and were healthy on the second. Main outcome measures In the collision detection task, the main outcomes were correct detections and response to a secondary identification task. In the simulated driving task, the outcomes were speed, lateral control, gap acceptance, overtaking behaviour, car following, vigilance and traffic light violations. Results Those with a cold detected fewer collisions and had a higher divided attention error than those who were healthy. Many basic driving skills were unimpaired by the illness. However, those with a cold were slower at responding to unexpected events and spent a greater percentage of time driving at a headway of <2 s. Conclusions The finding that having a common cold is associated with reduced ability to detect collisions and respond quickly to unexpected events is of practical importance. Further research is now required to examine the efficacy of information campaigns and countermeasures such as caffeine. PMID:22761287

  10. An electric scooter simulation program for training the driving skills of stroke patients with mobility problems: a pilot study.

    PubMed

    Jannink, Michiel J A; Erren-Wolters, C Victorien; de Kort, Alexander C; van der Kooij, Herman

    2008-12-01

    This paper describes an electric scooter simulation program and a first evaluation study in which we explored if it is possible to train the driving skills of future users of electric mobility scooters by means of an electric scooter simulation program in addition to conventional electric scooter training. Within this explorative study,10 stroke survivors were randomly assigned to either the control (n=5) or the electric scooter simulation intervention group (n=5). Participants were assessed twice on the functional evaluating rating scale. During the followup measurement, subjective experiences regarding both forms of electric scooter training were elicited by a questionnaire. After a training period of 5 weeks, both groups improved on the Functional Evaluation Rating Scale. It can be concluded that the patients with stroke were satisfied with the electric scooter simulation training.

  11. Effects of platooning on signal-detection performance, workload, and stress: A driving simulator study.

    PubMed

    Heikoop, Daniël D; de Winter, Joost C F; van Arem, Bart; Stanton, Neville A

    2017-04-01

    Platooning, whereby automated vehicles travel closely together in a group, is attractive in terms of safety and efficiency. However, concerns exist about the psychological state of the platooning driver, who is exempted from direct control, yet remains responsible for monitoring the outside environment to detect potential threats. By means of a driving simulator experiment, we investigated the effects on recorded and self-reported measures of workload and stress for three task-instruction conditions: (1) No Task, in which participants had to monitor the road, (2) Voluntary Task, in which participants could do whatever they wanted, and (3) Detection Task, in which participants had to detect red cars. Twenty-two participants performed three 40-min runs in a constant-speed platoon, one condition per run in counterbalanced order. Contrary to some classic literature suggesting that humans are poor monitors, in the Detection Task condition participants attained a high mean detection rate (94.7%) and a low mean false alarm rate (0.8%). Results of the Dundee Stress State Questionnaire indicated that automated platooning was less distressing in the Voluntary Task than in the Detection Task and No Task conditions. In terms of heart rate variability, the Voluntary Task condition yielded a lower power in the low-frequency range relative to the high-frequency range (LF/HF ratio) than the Detection Task condition. Moreover, a strong time-on-task effect was found, whereby the mean heart rate dropped from the first to the third run. In conclusion, participants are able to remain attentive for a prolonged platooning drive, and the type of monitoring task has effects on the driver's psychological state. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Can a novel web-based computer test predict poor simulated driving performance? a pilot study with healthy and cognitive-impaired participants.

    PubMed

    Nef, Tobias; Müri, René M; Bieri, Rahel; Jäger, Michael; Bethencourt, Nora; Tarnanas, Ioannis; Mosimann, Urs P

    2013-10-21

    Driving a car is a complex instrumental activity of daily living and driving performance is very sensitive to cognitive impairment. The assessment of driving-relevant cognition in older drivers is challenging and requires reliable and valid tests with good sensitivity and specificity to predict safe driving. Driving simulators can be used to test fitness to drive. Several studies have found strong correlation between driving simulator performance and on-the-road driving. However, access to driving simulators is restricted to specialists and simulators are too expensive, large, and complex to allow easy access to older drivers or physicians advising them. An easily accessible, Web-based, cognitive screening test could offer a solution to this problem. The World Wide Web allows easy dissemination of the test software and implementation of the scoring algorithm on a central server, allowing generation of a dynamically growing database with normative values and ensures that all users have access to the same up-to-date normative values. In this pilot study, we present the novel Web-based Bern Cognitive Screening Test (wBCST) and investigate whether it can predict poor simulated driving performance in healthy and cognitive-impaired participants. The wBCST performance and simulated driving performance have been analyzed in 26 healthy younger and 44 healthy older participants as well as in 10 older participants with cognitive impairment. Correlations between the two tests were calculated. Also, simulated driving performance was used to group the participants into good performers (n=70) and poor performers (n=10). A receiver-operating characteristic analysis was calculated to determine sensitivity and specificity of the wBCST in predicting simulated driving performance. The mean wBCST score of the participants with poor simulated driving performance was reduced by 52%, compared to participants with good simulated driving performance (P<.001). The area under the receiver

  13. Driving with Hemianopia, I: Detection Performance in a Driving Simulator

    PubMed Central

    Bowers, Alex R.; Mandel, Aaron J.; Goldstein, Robert B.; Peli, Eli

    2009-01-01

    Purpose This study was designed to examine the effect of homonymous hemianopia (HH) on detection of pedestrian figures in multiple realistic and hazardous situations within the controlled environment of a driving simulator. Methods Twelve people with complete HH and without visual neglect or cognitive decline and 12 matched (age, sex, and years of driving experience) normally sighted (NV) drivers participated. They drove predetermined city and rural highway routes (total, 120 minutes) during which pedestrian figures appeared at random intervals along the roadway (R-Peds; n = 144) and at intersections (I-Peds; n = 10). Detection rates and response times were derived from participant horn presses. Results Drivers with HH exhibited significantly (P < 0.001) lower R-Ped detection rates on the blind side than did NV drivers (range, 6%–100%). Detection of I-Peds on the blind side was also poor (8%–55%). Age and blind-side detection rates correlated negatively (Spearman r = −0.71, P = 0.009). Although blind-side response times of drivers with HH were significantly (P < 0.001) longer than those of NV drivers, most were within a commonly used 2.5-second guideline. Conclusions Most participants with HH had blind-side detection rates that seem incompatible with safe driving; however, the relationship of our simulator detection performance measures to on-road performance has yet to be established. In determining fitness to drive for people with HH, the results underscore the importance of individualized assessments including evaluations of blind-side hazard detection. PMID:19608541

  14. How do ankle braces affect braking performance? An experimental driving simulation study with healthy volunteers.

    PubMed

    Hofmann, Ulf Krister; Thumm, Stefan; Jordan, Maurice; Mittag, Falk; Rondak, Ina-Christine; Ipach, Ingmar

    2015-11-01

    Fitness to drive a car has been investigated increasingly over recent years. However, most research has focussed on perioperative driving performance, and few data are available on how orthoses influence the ability to perform an emergency stop. This study investigated the effect of 4 common ankle braces (Kallassy, CaligaLoc, Air-Stirrup, ASO) on reaction time, foot transfer time (together: brake response time) and brake force. The hypothesis was that wearing these braces on the right ankle impairs braking performance, specifically by increasing foot transfer time, but also by altering brake force. A car cabin was set up with measurement equipment to register reaction time, foot transfer time, brake response time and brake force under realistic spatial constraints. A crossover repeated measures design was used to test 30 healthy volunteers with and without each of the braces. All 4 braces resulted in statistically significantly increased foot transfer time (p < 0.001), compared with measurements without a brace. Reaction time with a brace was significantly prolonged, with the exception of the Kallasy. Brake force was not statistically significantly impaired. This study demonstrates that ankle braces lead to impaired braking performance. Depending on the type of brace, a stopping distance increase of more than 1 m at 100 km/h can be expected.

  15. Educational Biofeedback Driving Simulator as a Drink-Driving Prevention Strategy.

    ERIC Educational Resources Information Center

    Howat, Peter; And Others

    1991-01-01

    Used experimental driving simulator as basis for strategy to encourage a reduction in drunk driving prevalence using adult male subjects (n=36) who participated in a study group and controls (n=36). Results indicated study group subjects significantly decreased their drunk driving compared to the control group. (ABL)

  16. Educational Biofeedback Driving Simulator as a Drink-Driving Prevention Strategy.

    ERIC Educational Resources Information Center

    Howat, Peter; And Others

    1991-01-01

    Used experimental driving simulator as basis for strategy to encourage a reduction in drunk driving prevalence using adult male subjects (n=36) who participated in a study group and controls (n=36). Results indicated study group subjects significantly decreased their drunk driving compared to the control group. (ABL)

  17. A selective review of simulated driving studies: Combining naturalistic and hybrid paradigms, analysis approaches, and future directions.

    PubMed

    Calhoun, V D; Pearlson, G D

    2012-01-02

    Naturalistic paradigms such as movie watching or simulated driving that mimic closely real-world complex activities are becoming more widely used in functional magnetic resonance imaging (fMRI) studies both because of their ability to robustly stimulate brain connectivity and the availability of analysis methods which are able to capitalize on connectivity within and among intrinsic brain networks identified both during a task and in resting fMRI data. In this paper we review over a decade of work from our group and others on the use of simulated driving paradigms to study both the healthy brain as well as the effects of acute alcohol administration on functional connectivity during such paradigms. We briefly review our initial work focused on the configuration of the driving simulator and the analysis strategies. We then describe in more detail several recent studies from our group including a hybrid study examining distracted driving and compare resulting data with those from a separate visual oddball task (Fig. 6). The analysis of these data was performed primarily using a combination of group independent component analysis (ICA) and the general linear model (GLM) and in the various studies we highlight novel findings which result from an analysis of either 1) within-network connectivity, 2) inter-network connectivity, also called functional network connectivity, or 3) the degree to which the modulation of the various intrinsic networks were associated with the alcohol administration and the task context. Despite the fact that the behavioral effects of alcohol intoxication are relatively well known, there is still much to discover on how acute alcohol exposure modulates brain function in a selective manner, associated with behavioral alterations. Through the above studies, we have learned more regarding the impact of acute alcohol intoxication on organization of the brain's intrinsic connectivity networks during performance of a complex, real-world cognitive

  18. A Selective Review of Simulated Driving Studies: Combining Naturalistic and Hybrid Paradigms, Analysis Approaches, and Future Directions

    PubMed Central

    Calhoun, V. D.; Pearlson, G. D.

    2011-01-01

    Naturalistic paradigms such as movie watching or simulated driving that mimic closely real-world complex activities are becoming more widely used in functional magnetic resonance imaging (fMRI) studies both because of their ability to robustly stimulate brain connectivity and the availability of analysis methods which are able to capitalize on connectivity within and among intrinsic brain networks identified both during a task and in resting fMRI data. In this paper we review over a decade of work from our group and others on the use of simulated driving paradigms to study both the healthy brain as well as the effects of acute alcohol administration on functional connectivity during such paradigms. We briefly review our initial work focused on the configuration of the driving simulator and the analysis strategies. We then describe in more detail several recent studies from our group including a hybrid study examining distracted driving and compare resulting data with those from a separate visual oddball task. The analysis of these data were performed primarily using a combination of group independent component analysis (ICA) and the general linear model (GLM) and in the various studies we highlight novel findings which result from an analysis of either 1) within-network connectivity, 2) inter-network connectivity, also called functional network connectivity, or 3) the degree to which the modulation of the various intrinsic networks were associated with the alcohol administration and the task context. Despite the fact that the behavioral effects of alcohol intoxication are relatively well known, there is still much to discover on how acute alcohol exposure modulates brain function in a selective manner, associated with behavioral alterations. Through the above studies, we have learned more regarding the impact of acute alcohol intoxication on organization of the brain’s intrinsic connectivity networks during performance of a complex, real-world cognitive operation

  19. Anxiety, sedation, and simulated driving in binge drinkers.

    PubMed

    Aston, Elizabeth R; Shannon, Erin E; Liguori, Anthony

    2014-06-01

    The current study evaluated the relationships among trait anxiety, subjective response to alcohol, and simulated driving following a simulated alcohol binge. Sixty drinkers with a binge history completed the State Trait Anxiety Inventory (STAI), the Alcohol Use Questionnaire, and subsequently completed a driving simulation. Participants were then administered 0.2 g/kg ethanol at 30-min intervals (cumulative dose 0.8 g/kg). Following alcohol consumption, the Biphasic Alcohol Effects Scale (BAES) and visual analog scales of subjective impairment and driving confidence were administered, after which simulated driving was reassessed. Due to the emphasis on simulated driving after drinking in the current study, subjective response to alcohol (i.e., self-reported sedation, stimulation, impairment, and confidence in driving ability) was assessed once following alcohol consumption, as this is the time when drinkers tend to make decisions regarding legal driving ability. Alcohol increased driving speed, speeding tickets, and collisions. Sedation following alcohol predicted increased subjective impairment and decreased driving confidence. Subjective impairment was not predicted by sensitivity to stimulation or trait anxiety. High trait anxiety predicted low driving confidence after drinking and this relationship was mediated by sedation. Increased speed after alcohol was predicted by sedation, but not by trait anxiety or stimulation. Anxiety, combined with the sedating effects of alcohol, may indicate when consumption should cease. However, once driving is initiated, sensitivity to sedation following alcohol consumption is positively related to simulated driving speed.

  20. Anxiety, Sedation, and Simulated Driving in Binge Drinkers

    PubMed Central

    Aston, Elizabeth R.; Shannon, Erin E.; Liguori, Anthony

    2014-01-01

    The current study evaluated the relationships among trait anxiety, subjective response to alcohol, and simulated driving following a simulated alcohol binge. Sixty drinkers with a binge history completed the State Trait Anxiety Inventory (STAI), the Alcohol Use Questionnaire, and subsequently completed a driving simulation. Participants were then administered 0.2 g/kg ethanol at 30 minute intervals (cumulative dose 0.8 g/kg). Following alcohol consumption, the Biphasic Alcohol Effects Scale (BAES) and visual analog scales of subjective impairment and driving confidence were administered, after which simulated driving was re-assessed. Due to the emphasis on simulated driving after drinking in the current study, subjective response to alcohol (i.e., self-reported sedation, stimulation, impairment, and confidence in driving ability) was assessed once following alcohol consumption, as this is the time when drinkers tend to make decisions regarding legal driving ability. Alcohol increased driving speed, speeding tickets, and collisions. Sedation following alcohol predicted increased subjective impairment and decreased driving confidence. Subjective impairment was not predicted by sensitivity to stimulation or trait anxiety. High trait anxiety predicted low driving confidence after drinking and this relationship was mediated by sedation. Increased speed after alcohol was predicted by sedation, but not by trait anxiety or stimulation. Anxiety, combined with the sedating effects of alcohol, may indicate when consumption should cease. However, once driving is initiated, sensitivity to sedation following alcohol consumption is positively related to simulated driving speed. PMID:24955664

  1. [Use of driving simulators in psychological research].

    PubMed

    Andysz, Aleksandra; Waszkowska, Małgorzata; Merecz, Dorota; Drabek, Marcin

    2010-01-01

    The history of simulators dates back to the first decades of the twentieth century. At the beginning they were used to train pilots, and eventually they were used in the automotive industry for testing the strength of new vehicles and ergonomic solutions. With time research institutions and technical universities from outside the automotive industry have become more and more interested in simulators. Attractiveness of simulators for researchers is based on a number of important factors: they create the possibility of modeling, control and repeatability of different experimental situations, reducing at the same time the impact of confounding factors. Simulators have a great potential for data collection and processing. What's more, they are safe and ecologic. These values make them almost an ideal research tool. The article presents a review of psychological studies with use of vehicle driving simulators. It also points to advantages and disadvantages of these devices and outlines the future prospects for experimental research.

  2. In-car usage-based insurance feedback strategies. A comparative driving simulator study.

    PubMed

    Dijksterhuis, Chris; Lewis-Evans, Ben; Jelijs, Bart; Tucha, Oliver; de Waard, Dick; Brookhuis, Karel

    2016-09-01

    Usage-Based Insurances (UBI) enable policyholders to actively reduce the impact of vehicle insurance costs by adopting a safer and more eco-friendly driving style. UBI is especially relevant for younger drivers, who are a high-risk population. The effectiveness of UBI should be enhanced by providing in-car feedback optimised for individual drivers. Thirty young novice drivers were therefore invited to complete six experimental drives with an in-car interface that provided real-time information on rewards gained, their driving behaviour and the speed limit. Reward size was either displayed directly in euro, indirectly as a relatively large amount of credits, or as a percentage of the maximum available bonus. Also, interfaces were investigated that provided partial information to reduce the potential for driver distraction. Compared to a control no-UBI condition, behaviour improved similarly across interfaces, suggesting that interface personalisation after an initial familiarisation period could be feasible without compromising feedback effectiveness. Practitioner Summary: User experiences and effects on driving behaviour of six in-car interfaces were compared. The interface provided information on driving behaviour and rewards in a UBI setting. Results suggest that some personalisation of interfaces may be an option after an initial familiarisation period as driving behaviour improved similarly across interfaces.

  3. Electric Drive Study

    DTIC Science & Technology

    1987-03-01

    Track-Laying Combat Vehicles , and (3) Parametric Study of Electric Drive Component Technologies. The technology survey results are given in a separate...and projections of future electric drive system improvements relative to combat vehicle applications. Unclassified SECURITY CLASSIFICATION OF THIS...273 5.7.2.3.1 DC Homopolar Drum Machine, Design and Performance 5-278 APPENDIX A 19.5 TON AND 40.0 TON VEHICLE SPECIFICATION APPENDIX B ELECTRIC

  4. Driving performance and driver discomfort in an elevated and standard driving position during a driving simulation.

    PubMed

    Smith, Jordan; Mansfield, Neil; Gyi, Diane; Pagett, Mark; Bateman, Bob

    2015-07-01

    The primary purposes of a vehicle driver's seat, is to allow them to complete the driving task comfortably and safely. Within each class of vehicle (e.g. passenger, commercial, industrial, agricultural), there is an expected driving position to which a vehicle cabin is designed. This paper reports a study that compares two driving positions, in relation to Light Commercial Vehicles (LCVs), in terms of driver performance and driver discomfort. In the 'elevated' driving position, the seat is higher than usually used in road vehicles; this is compared to a standard driving position replicating the layout for a commercially available vehicle. It is shown that for a sample of 12 drivers, the elevated position did not, in general, show more discomfort than the standard position over a 60 min driving simulation, although discomfort increased with duration. There were no adverse effects shown for emergency stop reaction time or for driver headway for the elevated posture compared to the standard posture. The only body part that showed greater discomfort for the elevated posture compared to the standard posture was the right ankle. A second experiment confirmed that for 12 subjects, a higher pedal stiffness eliminated the ankle discomfort problem.

  5. The influence of curbs on driver behaviors in four-lane rural highways--A driving simulator based study.

    PubMed

    Yang, Qiang; Overton, Ryan; Han, Lee D; Yan, Xuedong; Richards, Stephen H

    2013-01-01

    The speed limit of 55mph (88km/h) is typically used on rural highways in the U.S. For locations where curbs are installed along these roadways, some transportation agencies have suggested the use of a lower 45mph (72km/h) speed limit because, according to AASHTO, running into curbs at high speeds may cause significant vehicular damage and even severe injuries. However, it has also been argued that lowering the speed limit after the installation of curbs may cause confusion in drivers, who do not perceive the risk associated with the newly installed curbs and tend to operate their vehicles at the same speed as before. To better understand driver behavior on rural highways before and after curb installation, and with different speed limits, researchers at the University of Tennessee conducted a series of experiments in two-lane and four-lane highways on a high-fidelity driving simulator. This paper mainly presents the findings from the four-lane study, and compares the results from the previous two-lane study. The scenario matrix consists of several dimensions including posted speed limit (45 and 55mph, or 72 and 88km/h), curb installation, lateral clearance between the edge of travel lane and the curb (2ft, 6ft, and no-curb, or 0.6m, 1.8m, and no-curb), weather (clear and fog), traffic conditions in the next lane (1400veh/h and 400veh/h), etc. For each subject under different experimental scenarios, detailed driving parameters, such as driving speed and vehicle position in the travel lane, were recorded and analyzed subsequently. Results of the study suggest that driver behaviors are influenced by the various factors in a complex and interrelated manner. It is likely that drivers do not perceive the risk from the curb in determining their speed on four-lane rural highways. However, it is found that curbs may provide certain guidance to drivers, especially in selecting lane position. Compared to the previous research in two-lane conditions, it is found that drivers

  6. The drive-wise project: driving simulator training increases real driving performance in healthy older drivers

    PubMed Central

    Casutt, Gianclaudio; Theill, Nathan; Martin, Mike; Keller, Martin; Jäncke, Lutz

    2014-01-01

    Background: Age-related cognitive decline is often associated with unsafe driving behavior. We hypothesized that 10 active training sessions in a driving simulator increase cognitive and on-road driving performance. In addition, driving simulator training should outperform cognitive training. Methods: Ninety-one healthy active drivers (62–87 years) were randomly assigned to one of three groups: (1) a driving simulator training group, (2) an attention training group (vigilance and selective attention), or (3) a control group. The main outcome variables were on-road driving and cognitive performance. Seventy-seven participants (85%) completed the training and were included in the analyses. Training gains were analyzed using a multiple regression analysis with planned orthogonal comparisons. Results: The driving simulator-training group showed an improvement in on-road driving performance compared to the attention-training group. In addition, both training groups increased cognitive performance compared to the control group. Conclusion: Driving simulator training offers the potential to enhance driving skills in older drivers. Compared to the attention training, the simulator training seems to be a more powerful program for increasing older drivers' safety on the road. PMID:24860497

  7. The use of meta-analysis or research synthesis to combine driving simulation or naturalistic study results on driver distraction.

    PubMed

    Caird, Jeff K; Johnston, Katherine A; Willness, Chelsea R; Asbridge, Mark

    2014-06-01

    Three important and inter-related topics are addressed in this paper. First, the importance of meta-analysis and research synthesis methods to combine studies on traffic safety, in general, and on driver distraction, in particular, is briefly reviewed. Second, naturalistic, epidemiologic, and driving simulation studies on driver distraction are used to illustrate convergent and divergent results that have accumulated thus far in this domain of research. In particular, mobile phone conversation, passenger presence, and text messaging naturalistic studies use meta-analyses and research syntheses to illustrate important patterns of results that are in need of more in-depth study. Third, a number of driver distraction study limitations such as poorly defined dependent variables, lack of methodological detail, and omission of statistical information prevent the integration of many studies into meta-analyses. In addition, the overall quality of road safety studies suffers from these same limitations and suggestions for improvement are made to guide researchers and reviewers. Practical Applications. The use of research synthesis and meta-analysis provide comprehensive estimates of the impact of distractions on driving performance, which can be used to guide public policy and future research. Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

  8. Immobilisation of the knee and ankle and its impact on drivers' braking times: a driving simulator study.

    PubMed

    Waton, A; Kakwani, R; Cooke, N J; Litchfield, D; Kok, D; Middleton, H; Irwin, L

    2011-07-01

    The purpose of this study was to investigate the effects of right leg restriction at the knee, ankle or both, on a driver's braking times. Previous studies have not investigated the effects of knee restriction on braking performance. A total of 23 healthy drivers performed a series of emergency braking tests in a driving simulator in either an above-knee plaster cast, a below-knee cast, or in a knee brace with an increasing range of restriction. The study showed that total braking reaction time was significantly longer when wearing an above-knee plaster cast, a below-knee plaster cast or a knee brace fixed at 0°, compared with braking normally (p < 0.001). Increases in the time taken to move the foot from the accelerator to the brake accounted for some of the increase in the total braking reaction time. Unexpectedly, thinking time also increased with the level of restriction (p < 0.001). The increase in braking time with an above-knee plaster cast in this study would increase the stopping distance at 30 miles per hour by almost 3 m. These results suggest that all patients wearing any lower-limb plaster cast or knee brace are significantly impaired in their ability to perform an emergency stop. We suggest changes to the legislation to prevent patients from driving with lower-limb plaster casts or knee braces.

  9. Obstacle Avoidance, Visual Detection Performance, and Eye-Scanning Behavior of Glaucoma Patients in a Driving Simulator: A Preliminary Study

    PubMed Central

    Prado Vega, Rocío; van Leeuwen, Peter M.; Rendón Vélez, Elizabeth; Lemij, Hans G.; de Winter, Joost C. F.

    2013-01-01

    The objective of this study was to evaluate differences in driving performance, visual detection performance, and eye-scanning behavior between glaucoma patients and control participants without glaucoma. Glaucoma patients (n = 23) and control participants (n = 12) completed four 5-min driving sessions in a simulator. The participants were instructed to maintain the car in the right lane of a two-lane highway while their speed was automatically maintained at 100 km/h. Additional tasks per session were: Session 1: none, Session 2: verbalization of projected letters, Session 3: avoidance of static obstacles, and Session 4: combined letter verbalization and avoidance of static obstacles. Eye-scanning behavior was recorded with an eye-tracker. Results showed no statistically significant differences between patients and control participants for lane keeping, obstacle avoidance, and eye-scanning behavior. Steering activity, number of missed letters, and letter reaction time were significantly higher for glaucoma patients than for control participants. In conclusion, glaucoma patients were able to avoid objects and maintain a nominal lane keeping performance, but applied more steering input than control participants, and were more likely than control participants to miss peripherally projected stimuli. The eye-tracking results suggest that glaucoma patients did not use extra visual search to compensate for their visual field loss. Limitations of the study, such as small sample size, are discussed. PMID:24146975

  10. A simulator study on the impact of traffic calming measures in urban areas on driving behavior and workload.

    PubMed

    Ariën, Caroline; Jongen, Ellen M M; Brijs, Kris; Brijs, Tom; Daniels, Stijn; Wets, Geert

    2013-12-01

    This study examined the impact of traffic calming measures (TCM) on major roads in rural and urban areas. More specifically we investigated the effect of gate constructions located at the entrance of the urban area and horizontal curves within the urban area on driving behavior and workload. Forty-six participants completed a 34km test-drive on a driving simulator with eight thoroughfare configurations, i.e., 2 (curves: present, absent)×2 (gates: present, absent)×2 (peripheral detection task (PDT): present, absent) in a within-subject design. PDT performance (mean response time (RT) and hit rate) indicated that drivers experienced the road outside the urban area as cognitively less demanding relative to the more complex road environment inside the urban area. Whereas curves induced a speed reduction that was sustained throughout the entire urban area, variability of acceleration/deceleration and lateral position were increased. In addition, PDT performance indicated higher workload when curves were present (versus absent). Gate constructions locally reduced speed (i.e., shortly before and after the entrance) and slightly increased variability of acceleration/deceleration and lateral position nearby the entrance. However, the effects on SDL-A/D and SDLP are too small to expect traffic safety problems. It can be concluded that both curves and gate constructions can improve traffic safety. Notwithstanding, the decision to implement these measures will depend on contextual factors such as whether the road serves a traffic-, rather than a residential function. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Simulated driving performance of combat veterans with mild tramatic brain injury and posttraumatic stress disorder: a pilot study.

    PubMed

    Classen, Sherrilene; Levy, Charles; Meyer, Dustin L; Bewernitz, Megan; Lanford, Desiree N; Mann, William C

    2011-01-01

    We determined differences in driving errors between combat veterans with mild traumatic brain injury and posttraumatic stress disorder and healthy control participants. We compared 18 postdeployed combat veterans with 20 control participants on drivingerrors in a driving simulator. Combat veterans were more likely to be male; were younger; and had more racial diversity, less formal education, and lower cognitive scores than control participants. Control participants made more signaling errors (t [19] = -2.138, p = .046, SE = 0.395), but combat veterans made more overspeeding (t [17.3] = 4.095, p = .001, SE = 0.708) and adjustment-to-stimuli (t [17] = 2.380, p = .029, SE = 0.140) errors. Young age was related to overspeeding. Combat veterans made more critical driving errors than did control participants. Such errors made on the road may lead to crashes or injuries. Although limited in generalizability, these findings provide early support for developing safe driving interventions for combat veterans.

  12. Determination of pre-impact occupant postures and analysis of consequences on injury outcome. Part I: a driving simulator study.

    PubMed

    Hault-Dubrulle, Audrey; Robache, Frederic; Pacaux, Marie-Pierre; Morvan, Herve

    2011-01-01

    This paper considers pre-impact vehicle maneuvers and analyzes the resulting driver motion from their comfort seating position. Part I of this work consists of analyzing the driver behavior during a crash. The study is conducted using the LAMIH driving simulator and involves 76 participants. The emergency situation is created by a truck emerging from behind a tractor on the opposite side of the road and tearing along the participant. The driver positioning throughout the simulation is recorded via five video cameras allowing view of the front scene, the driver face, feet and pedals, hands on the steering wheel and global lateral view. Data related to braking force, seat pressure, muscular activity for major groups of muscles and actions on the steering wheel are also collected. The typical response to this type of emergency event is to brace rearward into the seat and to straighten the arms against the steering wheel, or, to swerve to attempt to avoid the impacting vehicle. While turning the steering wheel, the forearm can be directly positioned on the airbag module at time of crash which represents a potential injurious situation. These positions are used in Part II to determine scenario of positions for numerical simulation of a frontal collision. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Advanced Motor Drives Studies

    NASA Technical Reports Server (NTRS)

    Ehsani, M.; Tchamdjou, A.

    1997-01-01

    This report presents an evaluation of advanced motor drive systems as a replacement for the hydrazine fueled APU units. The replacement technology must meet several requirements which are particular to the space applications and the Orbiter in general. Some of these requirements are high efficiency, small size, high power density. In the first part of the study several motors are compared, based on their characteristics and in light of the Orbiter requirements. The best candidate, the brushless DC is chosen because of its particularly good performance with regards to efficiency. Several power electronics drive technologies including the conventional three-phase hard switched and several soft-switched inverters are then presented. In the last part of the study, a soft-switched inverter is analyzed and compared to its conventional hard-switched counterpart. Optimal efficiency is a basic requirement for space applications and the soft-switched technology represents an unavoidable trend for the future.

  14. Chinese carless young drivers' self-reported driving behavior and simulated driving performance.

    PubMed

    Zhang, Qian; Jiang, Zuhua; Zheng, Dongpeng; Man, Dong; Xu, Xunnan

    2013-01-01

    Carless young drivers refers to those drivers aged between 18 and 25 years who have a driver's license but seldom have opportunities to practice their driving skills because they do not have their own cars. Due to China's lower private car ownership, many young drivers become carless young drivers after licensure, and the safety issue associated with them has raised great concern in China. This study aims to provide initial insight into the self-reported driving behaviors and simulated driving performance of Chinese carless young drivers. Thirty-three carless young drivers and 32 young drivers with their own cars (as a comparison group) participated in this study. A modified Driver Behavior Questionnaire (DBQ) with a 4-factor structure (errors, violations, attention lapses, and memory lapses) was used to study carless young drivers' self-reported driving behaviors. A simulated driving experiment using a low-cost, fixed-base driving simulator was conducted to measure their simulated driving performance (errors, violations, attention lapses, driving maintenance, reaction time, and accidents). Self-reported DBQ outcomes showed that carless young drivers reported similar errors, more attention lapses, fewer memory lapses, and significantly fewer violation behaviors relative to young drivers with their own cars, whereas simulated driving results revealed that they committed significantly more errors, attention lapses, and violation behaviors than the comparison group. Carless young drivers had a lower ability to maintain the stability of speed and lane position, drove more cautiously approaching and passing through red traffic lights, and committed more accidents during simulated driving. A tendency to speed was not found among carless young drivers; their average speed and speeding frequency were all much lower than that of the comparison group. Lifetime mileage was the only significant predictor of carless young drivers' self-reported violations, simulated violations

  15. Assessment of driving-related performance in chronic whiplash using an advanced driving simulator.

    PubMed

    Takasaki, Hiroshi; Treleaven, Julia; Johnston, Venerina; Rakotonirainy, Andry; Haines, Andrew; Jull, Gwendolen

    2013-11-01

    Driving is often nominated as problematic by individuals with chronic whiplash associated disorders (WAD), yet driving-related performance has not been evaluated objectively. The purpose of this study was to test driving-related performance in persons with chronic WAD against healthy controls of similar age, gender and driving experience to determine if driving-related performance in the WAD group was sufficiently impaired to recommend fitness to drive assessment. Driving-related performance was assessed using an advanced driving simulator during three driving scenarios; freeway, residential and a central business district (CBD). Total driving duration was approximately 15min. Five driving tasks which could cause a collision (critical events) were included in the scenarios. In addition, the effect of divided attention (identify red dots projected onto side or rear view mirrors) was assessed three times in each scenario. Driving performance was measured using the simulator performance index (SPI) which is calculated from 12 measures. z-Scores for all SPI measures were calculated for each WAD subject based on mean values of the control subjects. The z-scores were then averaged for the WAD group. A z-score of ≤-2 indicated a driving failing grade in the simulator. The number of collisions over the five critical events was compared between the WAD and control groups as was reaction time and missed response ratio in identifying the red dots. Seventeen WAD and 26 control subjects commenced the driving assessment. Demographic data were comparable between the groups. All subjects completed the freeway scenario but four withdrew during the residential and eight during the CBD scenario because of motion sickness. All scenarios were completed by 14 WAD and 17 control subjects. Mean z-scores for the SPI over the three scenarios was statistically lower in the WAD group (-0.3±0.3; P<0.05) but the score was not below the cut-off point for safe driving. There were no

  16. Study Sheds Light on Safety of Driving with Epilepsy

    MedlinePlus

    ... Study Sheds Light on Safety of Driving With Epilepsy Those who had longer seizures during driving tests ... SUNDAY, Dec. 4, 2016 (HealthDay News) -- People with epilepsy who experienced longer seizures during a simulated driving ...

  17. Mental workload when driving in a simulator: effects of age and driving complexity.

    PubMed

    Cantin, Vincent; Lavallière, Martin; Simoneau, Martin; Teasdale, Normand

    2009-07-01

    Driving errors for older drivers may result from a higher momentary mental workload resulting from complex driving situations, such as intersections. The present study examined if the mental workload of young and older active drivers vary with the difficulty of the driving context. We adopted the probe reaction time (RT) technique to measure the workload while driving in a simulator. The technique provided clear instructions about the primary (driving) and secondary (RT) tasks. To avoid structural interference, the secondary task consisted of responding as rapidly as possible with a vocal response ("top") to an auditory stimulus. Participants drove through a continuous 26.4-km scenario including rural and urban sections and probes (stimuli) were given in a baseline static condition and in three different driving contexts embedded into the overall driving scenario. Specifically, stimuli were given randomly when (a) driving on straight roads at a constant speed, (b) approaching intersections for which the driver had to stop the car, and (c) when overtaking a slower vehicle. Unless a driving error was made, drivers did not need any emergency responses. Reaction time was defined as the temporal interval between the auditory stimulus and the onset of the corresponding verbal response detected from the analog signal of a piezo-electric microphone fixed on a headset (ms accuracy). Baseline RTs were similar for both groups. Both groups showed longer RTs when driving and RTs increased as the complexity of the driving contexts increased (driving straights, intersections, overtaking maneuvers). Compared to younger drivers, however, older drivers showed longer RTs for all driving contexts and the most complex driving context (overtaking maneuvers) yielded a disproportionate increase. In conclusion, driving leads to a greater mental workload for the older drivers than for the younger drivers and this effect was exacerbated by the more complex driving context (overtaking

  18. Commentary training improves responsiveness to hazards in a driving simulator.

    PubMed

    Crundall, David; Andrews, Ben; van Loon, Editha; Chapman, Peter

    2010-11-01

    Can commentary driving produce safer drivers? Producing a verbal commentary of potential hazards during driving has long been considered by the police to improve hazard perception skills. In this study we investigated whether learner drivers would benefit from being trained to produce a commentary drive. All learners were initially assessed on a virtual route in a driving simulator that contained 9 hazards. One group of drivers was then trained in commentary driving, and their subsequent simulated driving behaviour was compared to a control group. The results showed that the trained group had fewer crashes, reduced their speed sooner on approach to hazards, and applied pressure to the brakes sooner than untrained drivers. Conversely the untrained drivers' behaviour on approach to hazards was symptomatic of being surprised at the appearance of the hazards. The benefit of training was found to be greater for certain types of hazard than others.

  19. Driver's behavioural changes with new intelligent transport system interventions at railway level crossings--A driving simulator study.

    PubMed

    Larue, Grégoire S; Kim, Inhi; Rakotonirainy, Andry; Haworth, Narelle L; Ferreira, Luis

    2015-08-01

    Improving safety at railway level crossings is an important issue for the Australian transport system. Governments, the rail industry and road organisations have tried a variety of countermeasures for many years to improve railway level crossing safety. New types of intelligent transport system (ITS) interventions are now emerging due to the availability and the affordability of technology. These interventions target both actively and passively protected railway level crossings and attempt to address drivers' errors at railway crossings, which are mainly a failure to detect the crossing or the train and misjudgement of the train approach speed and distance. This study aims to assess the effectiveness of three emerging ITS that the rail industry considers implementing in Australia: a visual in-vehicle ITS, an audio in-vehicle ITS, as well as an on-road flashing beacons intervention. The evaluation was conducted on an advanced driving simulator with 20 participants per trialled technology, each participant driving once without any technology and once with one of the ITS interventions. Every participant drove through a range of active and passive crossings with and without trains approaching. Their speed approach of the crossing, head movements and stopping compliance were measured. Results showed that driver behaviour was changed with the three ITS interventions at passive crossings, while limited effects were found at active crossings, even with reduced visibility. The on-road intervention trialled was unsuccessful in improving driver behaviour; the audio and visual ITS improved driver behaviour when a train was approaching. A trend toward worsening driver behaviour with the visual ITS was observed when no trains were approaching. This trend was not observed for the audio ITS intervention, which appears to be the ITS intervention with the highest potential for improving safety at passive crossings.

  20. Developing a driving simulator based functional object detection task.

    PubMed

    Goodenough, Richard R; Brooks, Johnell O; Crisler, Matthew C; Rosopa, Patrick J

    2012-10-01

    The purpose of this study was to validate a driving simulator-based tool for assessing functional visual scanning while driving (Goodenough, 2010) by replicating a previous study and assessing whether the results of the task are moderated by strategic decisions regarding task prioritization. Participants completed a functional object detection task that includes a peripheral target detection task and a central braking response task. Results indicated that the simulator task can identify differences in older and younger participants' abilities to functionally scan the driving environment and these differences appear unaffected by prioritizing either the scanning or braking task. Implications are discussed.

  1. Driving simulator sickness: Impact on driving performance, influence of blood alcohol concentration, and effect of repeated simulator exposures.

    PubMed

    Helland, Arne; Lydersen, Stian; Lervåg, Lone-Eirin; Jenssen, Gunnar D; Mørland, Jørg; Slørdal, Lars

    2016-09-01

    Simulator sickness is a major obstacle to the use of driving simulators for research, training and driver assessment purposes. The purpose of the present study was to investigate the possible influence of simulator sickness on driving performance measures such as standard deviation of lateral position (SDLP), and the effect of alcohol or repeated simulator exposure on the degree of simulator sickness. Twenty healthy male volunteers underwent three simulated driving trials of 1h's duration with a curvy rural road scenario, and rated their degree of simulator sickness after each trial. Subjects drove sober and with blood alcohol concentrations (BAC) of approx. 0.5g/L and 0.9g/L in a randomized order. Simulator sickness score (SSS) did not influence the primary outcome measure SDLP. Higher SSS significantly predicted lower average speed and frequency of steering wheel reversals. These effects seemed to be mitigated by alcohol. Higher BAC significantly predicted lower SSS, suggesting that alcohol inebriation alleviates simulator sickness. The negative relation between the number of previous exposures to the simulator and SSS was not statistically significant, but is consistent with habituation to the sickness-inducing effects, as shown in other studies. Overall, the results suggest no influence of simulator sickness on SDLP or several other driving performance measures. However, simulator sickness seems to cause test subjects to drive more carefully, with lower average speed and fewer steering wheel reversals, hampering the interpretation of these outcomes as measures of driving impairment and safety. BAC and repeated simulator exposures may act as confounding variables by influencing the degree of simulator sickness in experimental studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. In the eye of the beholder: A simulator study of the impact of Google Glass on driving performance.

    PubMed

    Young, Kristie L; Stephens, Amanda N; Stephan, Karen L; Stuart, Geoffrey W

    2016-01-01

    This study examined whether, and to what extent, driving is affected by reading text on Google Glass. Reading text requires a high level of visual resources and can interfere with safe driving. However, it is currently unclear if the impact of reading text on a head-mounted display, such as Google Glass (Glass), will differ from that found with more traditional head-down electronic devices, such as a dash-mounted smartphone. A total of 20 drivers (22-48 years) completed the Lane Change Test while driving undistracted and while reading text on Glass and on a smartphone. Measures of lateral vehicle control and event detection were examined along with subjective workload and secondary task performance. Results revealed that drivers' lane keeping ability was significantly impaired by reading text on both Glass and the smartphone. When using Glass, drivers also failed to detect a greater number of lane change signs compared to when using the phone or driving undistracted. In terms of subjective workload, drivers rated reading on Glass as subjectively easier than on the smartphone, which may possibly encourage greater use of this device while driving. Overall, the results suggest that, despite Glass allowing drivers to better maintain their visual attention on the forward scene, drivers are still not able to effectively divide their cognitive attention across the Glass display and the road environment, resulting in impaired driving performance. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Polar-direct-drive simulations and experiments

    SciTech Connect

    Marozas, J.A.; Marshall, F.J.; Craxton, R.S.; Igumenshchev, I.V.; Skupsky, S.; Bonino, M.J.; Collins, T.J.B.; Epstein, R.; Glebov, V.Yu.; Jacobs-Perkins, D.; Knauer, J.P.; McCrory, R.L.; McKenty, P.W.; Meyerhofer, D.D.; Noyes, S.G.; Radha, P.B.; Sangster, T.C.; Seka, W.; Smalyuk, V.A.

    2006-05-15

    Polar direct drive (PDD) [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] will allow direct-drive ignition experiments on the National Ignition Facility (NIF) [J. Paisner et al., Laser Focus World 30, 75 (1994)] as it is configured for x-ray drive. Optimal drive uniformity is obtained via a combination of beam repointing, pulse shapes, spot shapes, and/or target design. This article describes progress in the development of standard and 'Saturn' [R. S. Craxton and D. W. Jacobs-Perkins, Phys. Rev. Lett. 94, 0952002 (2005)] PDD target designs. Initial evaluation of experiments on the OMEGA Laser System [T. R. Boehly et al., Rev. Sci. Instrum. 66, 508 (1995)] and simulations were carried out with the two-dimensional hydrodynamics code SAGE [R. S. Craxton et al., Phys. Plasmas 12, 056304 (2005)]. This article adds to this body of work by including fusion particle production and transport as well as radiation transport within the two-dimensional DRACO [P. B. Radha et al., Phys. Plasmas 12, 032702 (2005)] hydrodynamics simulations used to model experiments. Forty OMEGA beams arranged in six rings to emulate the NIF x-ray-drive configuration are used to perform direct-drive implosions of CH shells filled with D{sub 2} gas. Target performance was diagnosed with framed x-ray backlighting and by the measured fusion yield. Saturn target experiments have resulted in {approx}75% of the yield from energy-equivalent, symmetrically irradiated implosions. The results of the two-dimensional PDD simulations performed with DRACO are in good agreement with experimental x-ray radiographs. DRACO is being used to further optimize standard PDD designs. In addition, DRACO simulations of NIF-scale PDD designs show ignition with a gain of 20 and the development of a 40 {mu}m radius, 10 keV region with a neutron-averaged {rho}r of 1270 mg/cm{sup 2} near stagnation.

  4. Sleepiness and ethanol effects on simulated driving.

    PubMed

    Roehrs, T; Beare, D; Zorick, F; Roth, T

    1994-02-01

    Twelve healthy young men were assessed in each of four experimental conditions presented in a Latin Square design: 8-hr time in bed (TIB) and placebo, 4-hr TIB and placebo, 8-hr TIB and ethanol, and 4-hr TIB and ethanol. After consuming ethanol (0.6 g/kg) or placebo (0900-0930 hr) with 20% supplements at 1030 and 1100 hr, subjects were tested for sleepiness (Multiple Sleep Latency Test at 1000, 1200, 1400, and 1600 hr) and divided attention (1030 hr) performance on day 1, and for simulated driving and divided attention (1000-1200 and 1400-1600 hr) performance on day 2. In the morning testing, with breath ethanol concentrations (BECs) averaging 0.049%, sleepiness was increased, divided attention reaction times increased (on both days), and simulated driving performance was disturbed in the ethanol and 4-hr TIB relative to placebo. Similarly in the afternoon, with BECs averaging 0.013%, the ethanol and 4-hr TIB condition increased sleepiness and disrupted divided attention and simulated driving performance. The results show that sleepiness and low-dose ethanol combine to impair simulated automobile driving, an impairment that extends beyond the point at which BEC reaches zero. They provide a possible explanation for the incidence of alcohol-related automobile accidents at low BECs.

  5. Motorcyclist's lane position as a factor in right-of-way violation collisions: a driving simulator study.

    PubMed

    Sager, Bertrand; Yanko, Matthew R; Spalek, Thomas M; Froc, David J; Bernstein, Daniel M; Dastur, Farhad N

    2014-11-01

    A driver turning left and failing to notice an oncoming motorcyclist until too late is the most common cause of motorcycle collisions. Consequently, much previous research has focused on motorcycle properties, such as size, shape, and color to explain its inconspicuousness. However, collision statistics remain largely unchanged, suggesting that the issue may not be related solely to the motorcycle's static properties. In the present study, we examined a different characteristic of the motorcycle, namely its trajectory of approach. Seventeen participants faced oncoming traffic in a high-fidelity driving simulator and indicated when gaps were safe enough for them to turn left at an intersection. We manipulated the size of the gaps and the type of oncoming vehicle over 135 trials, with gap sizes varying from 3 to 5s, and vehicles consisting of either a car, a motorcycle in the left-of-lane position, or a motorcycle in the right-of-lane position. Our results show that drivers are more likely to turn in front of an oncoming motorcycle when it travels in the left-of-lane position than when it travels in the right-of-lane position. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Driver Education and Driving Simulators.

    ERIC Educational Resources Information Center

    Fox, James H.

    This study was concerned with--(1) the conditions of transfer of training, (2) armed forces research on the use of synthetic training devices in the learning of complex skills, (3) armed forces research on the use of training devices in learning judgmental skills, and (4) training devices used in driver education. A section with a summary,…

  7. Lithographically fabricated silicon microreactor for operando QEXAFS studies in exhaust gas catalysis during simulation of a standard driving cycle

    NASA Astrophysics Data System (ADS)

    Doronkin, D. E.; Baier, S.; Sheppard, T.; Benzi, F.; Grunwaldt, J.-D.

    2016-05-01

    Selective catalytic reduction of NOx by ammonia over Cu-ZSM-5 was monitored by operando QEXAFS during simulation of the New European Driving Cycle. The required fast temperature transients were realized using a novel silicon microreactor, enabling simultaneous spectroscopic and kinetic analysis by X-ray absorption spectroscopy (XAS) and mass spectrometry (MS). Periods of high temperature were correlated to an increase in both N2 production and change of coordination of Cu sites. This operando approach using Si microreactors can be applied to other heterogeneous catalytic systems involving fast temperature transients.

  8. Effects of advertising billboards during simulated driving.

    PubMed

    Edquist, Jessica; Horberry, Tim; Hosking, Simon; Johnston, Ian

    2011-05-01

    There is currently a great deal of interest in the problem of driver distraction. Most research focuses on distractions from inside the vehicle, but drivers can also be distracted by objects outside the vehicle. Major roads are increasingly becoming sites for advertising billboards, and there is little research on the potential effects of this advertising on driving performance. The driving simulator experiment presented here examines the effects of billboards on drivers, including older and inexperienced drivers who may be more vulnerable to distractions. The presence of billboards changed drivers' patterns of visual attention, increased the amount of time needed for drivers to respond to road signs, and increased the number of errors in this driving task.

  9. Concurrent audio-visual feedback for supporting drivers at intersections: A study using two linked driving simulators.

    PubMed

    Houtenbos, M; de Winter, J C F; Hale, A R; Wieringa, P A; Hagenzieker, M P

    2017-04-01

    A large portion of road traffic crashes occur at intersections for the reason that drivers lack necessary visual information. This research examined the effects of an audio-visual display that provides real-time sonification and visualization of the speed and direction of another car approaching the crossroads on an intersecting road. The location of red blinking lights (left vs. right on the speedometer) and the lateral input direction of beeps (left vs. right ear in headphones) corresponded to the direction from where the other car approached, and the blink and beep rates were a function of the approaching car's speed. Two driving simulators were linked so that the participant and the experimenter drove in the same virtual world. Participants (N = 25) completed four sessions (two with the audio-visual display on, two with the audio-visual display off), each session consisting of 22 intersections at which the experimenter approached from the left or right and either maintained speed or slowed down. Compared to driving with the display off, the audio-visual display resulted in enhanced traffic efficiency (i.e., greater mean speed, less coasting) while not compromising safety (i.e., the time gap between the two vehicles was equivalent). A post-experiment questionnaire showed that the beeps were regarded as more useful than the lights. It is argued that the audio-visual display is a promising means of supporting drivers until fully automated driving is technically feasible. Copyright © 2016. Published by Elsevier Ltd.

  10. Simulation model for a seven-phase BLDCM drive system

    NASA Astrophysics Data System (ADS)

    Park, Sang-Hoon; Lee, Won-Cheol; Lee, Jung-Hyo; Yu, Jae-Sung; Kim, Gyu-Sik; Won, Chung-Yuen

    2007-12-01

    BLDC motors have many advantages over brushed DC motors and induction motors. So, BLDC motors extend their application to many industrial fields. In this paper, the digital simulation and modeling of a 7-phase brushless DC motor have been presented. The 14-switch inverter and a 7-phase brushless DC motor drive system are simulated using hysteresis current controller and logic of switching pattern with the Boolean¡s function. Through some simulations, we found that our modeling and analysis of a 7-phase BLDCM with PWM inverter would be helpful for the further studies of the multi-phase BLDCM drive systems.

  11. Driving assessment and rehabilitation using a driving simulator in individuals with traumatic brain injury: A scoping review.

    PubMed

    Imhoff, Sarah; Lavallière, Martin; Teasdale, Normand; Fait, Philippe

    2016-06-30

    Due to the heterogeneity of the lesion following a traumatic brain injury (TBI) and the complexity of the driving task, driving assessment and rehabilitation in TBI individuals is challenging. Conventional driving assessment (on-road and in-clinic evaluations) has failed demonstrating effectiveness to assess fitness to drive in TBI individuals. We aimed to determine if driving simulators represent an interesting opportunity in assessing and rehabilitating driving skills in TBI individuals. We searched PubMed, CINAHL and Cochrane library databases between 27-02-2014 and 08-04-2014 for articles published since 2000 with the contents of simulator driving assessment and rehabilitation. Out of 488, eight articles with the subject of simulator driving assessment and two with the subject of simulator driving rehabilitation in individuals with TBI were reviewed. Driving simulators represent a promising avenue for the assessment and rehabilitation of driving skills in TBI individuals as it allows control of stimuli in a safe, challenging and ecologically valid environment and offer the opportunity to measure and record driving performance. Additional studies, however, are needed to document strengths and limitations of this method.

  12. Relationship between workload and mind-wandering in simulated driving.

    PubMed

    Zhang, Yuyu; Kumada, Takatsune

    2017-01-01

    Mental workload and mind-wandering are highly related to driving safety. This study investigated the relationship between mental workload and mind-wandering while driving. Participants (N = 40) were asked to perform a car following task in driving simulator, and report whether they had experienced mind-wandering upon hearing a tone. After driving, participants reported their workload using the NASA-Task Load Index (TLX). Results revealed an interaction between workload and mind-wandering in two different perspectives. First, there was a negative correlation between workload and mind-wandering (r = -0.459, p < 0.01) for different individuals. Second, from temporal perspective workload and mind-wandering frequency increased significantly over task time and were positively correlated. Together, these findings contribute to understanding the roles of workload and mind-wandering in driving.

  13. Relationship between workload and mind-wandering in simulated driving

    PubMed Central

    2017-01-01

    Mental workload and mind-wandering are highly related to driving safety. This study investigated the relationship between mental workload and mind-wandering while driving. Participants (N = 40) were asked to perform a car following task in driving simulator, and report whether they had experienced mind-wandering upon hearing a tone. After driving, participants reported their workload using the NASA-Task Load Index (TLX). Results revealed an interaction between workload and mind-wandering in two different perspectives. First, there was a negative correlation between workload and mind-wandering (r = -0.459, p < 0.01) for different individuals. Second, from temporal perspective workload and mind-wandering frequency increased significantly over task time and were positively correlated. Together, these findings contribute to understanding the roles of workload and mind-wandering in driving. PMID:28467513

  14. The effects of cyclists present at rural intersections on speed behavior and workload of car drivers: a driving simulator study.

    PubMed

    Duivenvoorden, Kirsten; Hogema, Jeroen; Hagenzieker, Marjan; Wegman, Fred

    2015-01-01

    The objective was to gain insight into how the number of cyclists, the cyclist's approach direction, and the cyclist's action affect the speed and mental workload of drivers approaching rural intersections. In addition, the effects of a speed-reducing measure on the interaction between cyclists and motorized traffic were examined. An experiment was conducted in a moving-base driving simulator. Thirty participants completed 3 runs each in 3 conditions: a baseline, a plateau, and a chicane condition. Participants drove an 80 km/h rural distributor road with 8 intersections. Eight cyclist scenarios were developed varying in the number of cyclists and the direction from which they approached the participants' lane. The Peripheral Detection Task was used to measure workload objectively and continuously. A plateau ahead of the intersection resulted in drivers entering the bicycle crossing with lower driving speeds but did not result in less serious potential conflicts compared to intersections without the speed-reducing measure. With respect to the presence of cyclists, drivers approaching the intersection without cyclists reached a minimum speed at a greater distance from the bicycle crossing compared to approaching the intersection with multiple cyclists in the baseline condition. At intersections with plateaus, drivers drove slower when encountering multiple cyclists compared to no cyclists. At intersections without the speed-reducing measure, drivers drove slower, decelerated stronger, and decelerated at a shorter distance to the bicycle crossing when encountering a suddenly crossing cyclist compared to a yielding cyclist. Although drivers have the right of way at rural intersections, drivers' speed behavior was affected by the number and action of cyclists. From a road safety point of view, driving speeds at rural intersections need to be further reduced to limit the seriousness of potential conflicts between cyclists and motorized traffic.

  15. Development of a Headlight Glare Simulator for a Driving Simulator.

    PubMed

    Hwang, Alex D; Peli, Eli

    2013-07-01

    We describe the design and construction of a headlight glare simulator to be used with a driving simulator. The system combines a modified programmable off-the-shelf LED display board and a beamsplitter so that the LED lights, representing the headlights of oncoming cars, are superimposed over the driving simulator headlights image. Ideal spatial arrangement of optical components to avoid misalignments of the superimposed images is hard to achieve in practice and variations inevitably introduce some parallax. Furthermore, the driver's viewing position varies with driver's height and seating position preferences exacerbate such misalignment. We reduce the parallax errors using an intuitive calibration procedure (simple drag-and-drop alignment of nine LED positions with calibration dots on the screen). To simulate the dynamics of headlight brightness changes when two vehicles are approaching, LED intensity control algorithms based on both headlight and LED beam shapes were developed. The simulation errors were estimated and compared to real-world headlight brightness variability.

  16. Analysis of driver speeds under night driving conditions using a driving simulator.

    PubMed

    Bella, Francesco; Calvi, Alessandro; D'Amico, Fabrizio

    2014-06-01

    Accident statistics demonstrate that there should be a greater focus on nighttime driving to improve our knowledge of driver behavior under poor lighting conditions. However, the current geometric design criteria do not take into account driving at night. Moreover, studies that propose predictive models of operating speed only consider daytime driving conditions. This study compares driver speed behavior during daytime and nighttime driving and models operating speeds and speed differentials, identifying significant factors that influence speed behavior under different lighting conditions. The research was carried out using a driving simulator for a section of an existing two-lane rural road composed of 39 tangent-curve configurations. Speed profiles were recorded for 40 drivers under simulated daytime and nighttime driving conditions. New predictive speed models, differentiated for daytime and nighttime driving, are proposed that highlight the effects of different geometric predictors under different visibility conditions. Specifically, predictive models for operating speed on curves identified the inverse of the radius and the deflection angle of the curve as predictors under both driving conditions. For speed differentials based on the 85th percentile for maximum speed reduction (85 MSR), we found that the inverse of the approaching tangent length and of the curve radius significantly explained the dependent variable in both cases, with a higher dependence of nighttime 85 MSR on the curve geometry than on the tangent length. Tangent length had a significant effect on operating speed for independent tangents only for the daytime model, whereas the inverse of the previous radius was confirmed as a predictor for both visibility conditions. This research may influence design considerations for nighttime driving by providing evidence of the effects of nighttime conditions on driver speed choices and road safety. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Brief Report: Examining Driving Behavior in Young Adults with High Functioning Autism Spectrum Disorders--A Pilot Study Using a Driving Simulation Paradigm

    ERIC Educational Resources Information Center

    Reimer, Bryan; Fried, Ronna; Mehler, Bruce; Joshi, Gagan; Bolfek, Anela; Godfrey, Kathryn M.; Zhao, Nan; Goldin, Rachel; Biederman, Joseph

    2013-01-01

    Although it is speculated that impairments associated with autism spectrum disorder (ASD) will adversely affect driving performance, little is known about the actual extent and nature of the presumed deficits. Ten males (18-24 years of age) with a diagnosis of high functioning autism and 10 age matched community controls were recruited for a…

  18. Brief Report: Examining Driving Behavior in Young Adults with High Functioning Autism Spectrum Disorders--A Pilot Study Using a Driving Simulation Paradigm

    ERIC Educational Resources Information Center

    Reimer, Bryan; Fried, Ronna; Mehler, Bruce; Joshi, Gagan; Bolfek, Anela; Godfrey, Kathryn M.; Zhao, Nan; Goldin, Rachel; Biederman, Joseph

    2013-01-01

    Although it is speculated that impairments associated with autism spectrum disorder (ASD) will adversely affect driving performance, little is known about the actual extent and nature of the presumed deficits. Ten males (18-24 years of age) with a diagnosis of high functioning autism and 10 age matched community controls were recruited for a…

  19. Comparing treatment effects of oral THC on simulated and on-the-road driving performance: testing the validity of driving simulator drug research.

    PubMed

    Veldstra, J L; Bosker, W M; de Waard, D; Ramaekers, J G; Brookhuis, K A

    2015-08-01

    The driving simulator provides a safe and controlled environment for testing driving behaviour efficiently. The question is whether it is sensitive to detect drug-induced effects. The primary aim of the current study was to investigate the sensitivity of the driving simulator for detecting drug effects. As a case in point, we investigated the dose-related effects of oral ∆(9)-tetrahydrocannabinol (THC), i.e. dronabinol, on simulator and on-the-road driving performance in equally demanding driving tasks. Twenty-four experienced driver participants were treated with dronabinol (Marinol®; 10 and 20 mg) and placebo. Dose-related effects of the drug on the ability to keep a vehicle in lane (weaving) and to follow the speed changes of a lead car (car following) were compared within subjects for on-the-road versus in-simulator driving. Additionally, the outcomes of equivalence testing to alcohol-induced effects were investigated. Treatment effects found on weaving when driving in the simulator were comparable to treatment effects found when driving on the road. The effect after 10 mg dronabinol was however less strong in the simulator than on the road and inter-individual variance seemed higher in the simulator. There was, however, a differential treatment effect of dronabinol on reactions to speed changes of a lead car (car following) when driving on the road versus when driving in the simulator. The driving simulator was proven to be sensitive for demonstrating dronabinol-induced effects particularly at higher doses. Treatment effects of dronabinol on weaving were comparable with driving on the road but inter-individual variability seemed higher in the simulator than on the road which may have potential effects on the clinical inferences made from simulator driving. Car following on the road and in the simulator were, however, not comparable.

  20. Driving behaviour responses to a moose encounter, automatic speed camera, wildlife warning sign and radio message determined in a factorial simulator study.

    PubMed

    Jägerbrand, Annika K; Antonson, Hans

    2016-01-01

    In a driving simulator study, driving behaviour responses (speed and deceleration) to encountering a moose, automatic speed camera, wildlife warning sign and radio message, with or without a wildlife fence and in dense forest or open landscape, were analysed. The study consisted of a factorial experiment that examined responses to factors singly and in combination over 9-km road stretches driven eight times by 25 participants (10 men, 15 women). The aims were to: determine the most effective animal-vehicle collision (AVC) countermeasures in reducing vehicle speed and test whether these are more effective in combination for reducing vehicle speed; identify the most effective countermeasures on encountering moose; and determine whether the driving responses to AVC countermeasures are affected by the presence of wildlife fences and landscape characteristics. The AVC countermeasures that proved most effective in reducing vehicle speed were a wildlife warning sign and radio message, while automatic speed cameras had a speed-increasing effect. There were no statistically significant interactions between different countermeasures and moose encounters. However, there was a tendency for a stronger speed-reducing effect from the radio message warning and from a combination of a radio message and wildlife warning sign in velocity profiles covering longer driving distances than the statistical tests. Encountering a moose during the drive had the overall strongest speed-reducing effect and gave the strongest deceleration, indicating that moose decoys or moose artwork might be useful as speed-reducing countermeasures. Furthermore, drivers reduced speed earlier on encountering a moose in open landscape and had lower velocity when driving past it. The presence of a wildlife fence on encountering the moose resulted in smaller deceleration. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. An electrophysiological study of the impact of a Forward Collision Warning System in a simulator driving task.

    PubMed

    Bueno, Mercedes; Fabrigoule, Colette; Deleurence, Philippe; Ndiaye, Daniel; Fort, Alexandra

    2012-08-27

    Driver distraction has been identified as the most important contributing factor in rear-end collisions. In this context, Forward Collision Warning Systems (FCWS) have been developed specifically to warn drivers of potential rear-end collisions. The main objective of this work is to evaluate the impact of a surrogate FCWS and of its reliability according to the driver's attentional state by recording both behavioral and electrophysiological data. Participants drove following a lead motorcycle in a simplified simulator with or without a warning system which gave forewarning of the preceding vehicle braking. Participants had to perform this driving task either alone (simple task) or simultaneously with a secondary cognitive task (dual task). Behavioral and electrophysiological data contributed to revealing a positive effect of the warning system. Participants were faster in detecting the brake light when the system was perfect or imperfect, and the time and attentional resources allocation required for processing the target at higher cognitive level were reduced when the system was completely reliable. When both tasks were performed simultaneously, warning effectiveness was considerably affected at both performance and neural levels; however, the analysis of the brain activity revealed fewer differences between distracted and undistracted drivers when using the warning system. These results show that electrophysiological data could be a valuable tool to complement behavioral data and to have a better understanding of how these systems impact the driver.

  2. Validating a driving simulator using surrogate safety measures.

    PubMed

    Yan, Xuedong; Abdel-Aty, Mohamed; Radwan, Essam; Wang, Xuesong; Chilakapati, Praveen

    2008-01-01

    Traffic crash statistics and previous research have shown an increased risk of traffic crashes at signalized intersections. How to diagnose safety problems and develop effective countermeasures to reduce crash rate at intersections is a key task for traffic engineers and researchers. This study aims at investigating whether the driving simulator can be used as a valid tool to assess traffic safety at signalized intersections. In support of the research objective, this simulator validity study was conducted from two perspectives, a traffic parameter (speed) and a safety parameter (crash history). A signalized intersection with as many important features (including roadway geometries, traffic control devices, intersection surroundings, and buildings) was replicated into a high-fidelity driving simulator. A driving simulator experiment with eight scenarios at the intersection were conducted to determine if the subjects' speed behavior and traffic risk patterns in the driving simulator were similar to what were found at the real intersection. The experiment results showed that speed data observed from the field and in the simulator experiment both follow normal distributions and have equal means for each intersection approach, which validated the driving simulator in absolute terms. Furthermore, this study used an innovative approach of using surrogate safety measures from the simulator to contrast with the crash analysis for the field data. The simulator experiment results indicated that compared to the right-turn lane with the low rear-end crash history record (2 crashes), subjects showed a series of more risky behaviors at the right-turn lane with the high rear-end crash history record (16 crashes), including higher deceleration rate (1.80+/-1.20 m/s(2) versus 0.80+/-0.65 m/s(2)), higher non-stop right-turn rate on red (81.67% versus 57.63%), higher right-turn speed as stop line (18.38+/-8.90 km/h versus 14.68+/-6.04 km/h), shorter following distance (30

  3. A rear-end collision risk assessment model based on drivers' collision avoidance process under influences of cell phone use and gender-A driving simulator based study.

    PubMed

    Li, Xiaomeng; Yan, Xuedong; Wu, Jiawei; Radwan, Essam; Zhang, Yuting

    2016-12-01

    Driver's collision avoidance performance has a direct link to the collision risk and crash severity. Previous studies demonstrated that the distracted driving, such as using a cell phone while driving, disrupted the driver's performance on road. This study aimed to investigate the manner and extent to which cell phone use and driver's gender affected driving performance and collision risk in a rear-end collision avoidance process. Forty-two licensed drivers completed the driving simulation experiment in three phone use conditions: no phone use, hands-free, and hand-held, in which the drivers drove in a car-following situation with potential rear-end collision risks caused by the leading vehicle's sudden deceleration. Based on the experiment data, a rear-end collision risk assessment model was developed to assess the influence of cell phone use and driver's gender. The cell phone use and driver's gender were found to be significant factors that affected the braking performances in the rear-end collision avoidance process, including the brake reaction time, the deceleration adjusting time and the maximum deceleration rate. The minimum headway distance between the leading vehicle and the simulator during the rear-end collision avoidance process was the final output variable, which could be used to measure the rear-end collision risk and judge whether a collision occurred. The results showed that although cell phone use drivers took some compensatory behaviors in the collision avoidance process to reduce the mental workload, the collision risk in cell phone use conditions was still higher than that without the phone use. More importantly, the results proved that the hands-free condition did not eliminate the safety problem associated with distracted driving because it impaired the driving performance in the same way as much as the use of hand-held phones. In addition, the gender effect indicated that although female drivers had longer reaction time than male drivers in

  4. The effects of texting on driving performance in a driving simulator: the influence of driver age.

    PubMed

    Rumschlag, Gordon; Palumbo, Theresa; Martin, Amber; Head, Doreen; George, Rajiv; Commissaris, Randall L

    2015-01-01

    Distracted driving is a significant contributor to motor vehicle accidents and fatalities, and texting is a particularly significant form of driver distraction that continues to be on the rise. The present study examined the influence of driver age (18-59 years old) and other factors on the disruptive effects of texting on simulated driving behavior. While 'driving' the simulator, subjects were engaged in a series of brief text conversations with a member of the research team. The primary dependent variable was the occurrence of Lane Excursions (defined as any time the center of the vehicle moved outside the directed driving lane, e.g., into the lane for oncoming traffic or onto the shoulder of the road), measured as (1) the percent of subjects that exhibited Lane Excursions, (2) the number of Lane Excursions occurring and (3) the percent of the texting time in Lane Excursions. Multiple Regression analyses were used to assess the influence of several factors on driving performance while texting, including text task duration, texting skill level (subject-reported), texting history (#texts/week), driver gender and driver age. Lane Excursions were not observed in the absence of texting, but 66% of subjects overall exhibited Lane Excursions while texting. Multiple Regression analysis for all subjects (N=50) revealed that text task duration was significantly correlated with the number of Lane Excursions, and texting skill level and driver age were significantly correlated with the percent of subjects exhibiting Lane Excursions. Driver gender was not significantly correlated with Lane Excursions during texting. Multiple Regression analysis of only highly skilled texters (N=27) revealed that driver age was significantly correlated with the number of Lane Excursions, the percent of subjects exhibiting Lane Excursions and the percent of texting time in Lane Excursions. In contrast, Multiple Regression analysis of those drivers who self-identified as not highly skilled

  5. Effects of chewing gum on driving performance as evaluated by the STISIM driving simulator

    PubMed Central

    Yoo, Ingyu; Kim, Eun-Joo; Lee, Joo-Hyun

    2015-01-01

    [Purpose] The purpose of this study was to determine the effects of chewing gum on driving performance in a driving simulator. [Subjects] In total, 26 young licensed drivers participated. [Methods] The driving scenario was typical of an urban environment: a single-carriageway, two-way road consisting of a mix of curved and straight sections, with considerable levels of traffic, pedestrians, and parked cars. Mean distance driven above the speed limit, lane position, mean distance driven across the center line, and mean distance driven off the road were used as estimates of brake, accelerator, and steering control. The results were compared with those of a non-chewing gum control condition. [Results] The driving performance while chewing gum was significantly better: the mean distance driven above the speed limit was 26.61% shorter, and the mean distance driven off the road was 31.99% shorter. Lane position and mean distance driven across the center line did not differ significantly between the two conditions. [Conclusion] Chewing gum appears to enhance driving performance during a sustained attention driving task. PMID:26180329

  6. Commercial Motor Vehicle Driving Performance: An Examination of Attentional Resources and Control Using a Driving Simulator.

    PubMed

    McManus, Benjamin; Heaton, Karen; Stavrinos, Despina

    2017-04-03

    Commercial motor vehicle (CMV) drivers often multitask when driving to increase travel efficiency and to increase alertness. Secondary tasks have been shown to impact CMV driving differentially, and attentional resources have been posited as a key factor. However, underlying mechanisms of secondary task engagement on attention and task performance have not been fully examined. Additionally, it is unknown if attentional control moderates these differential effects of secondary tasks and task performance. The current study aimed to examine decrements in driving performance from a resource-control theory by determining the specific relation between attentional resources and attentional control. To achieve this goal, 2 objectives were determined. Objective 1 considered the differential impact of secondary tasks on attentional resources in CMV driving performance. Objective 2 investigated individual differences in attentional control in the sample of CMV drivers. Fifty CMV drivers (Mage = 39.8 years, SD = 8.36) completed the 10-min psychomotor vigilance task providing measures of attentional control and also drove in a CMV driving simulator 4 times while presented with 1 of 4 secondary tasks. Findings linked secondary tasks to attentional resources, which, consequently affected CMV driving performance. The mediating effect of attentional resources significantly differed among varying levels of attentional control. (PsycINFO Database Record

  7. Development of a Headlight Glare Simulator for a Driving Simulator

    PubMed Central

    Hwang, Alex D.; Peli, Eli

    2012-01-01

    We describe the design and construction of a headlight glare simulator to be used with a driving simulator. The system combines a modified programmable off–the-shelf LED display board and a beamsplitter so that the LED lights, representing the headlights of oncoming cars, are superimposed over the driving simulator headlights image. Ideal spatial arrangement of optical components to avoid misalignments of the superimposed images is hard to achieve in practice and variations inevitably introduce some parallax. Furthermore, the driver’s viewing position varies with driver’s height and seating position preferences exacerbate such misalignment. We reduce the parallax errors using an intuitive calibration procedure (simple drag-and-drop alignment of nine LED positions with calibration dots on the screen). To simulate the dynamics of headlight brightness changes when two vehicles are approaching, LED intensity control algorithms based on both headlight and LED beam shapes were developed. The simulation errors were estimated and compared to real-world headlight brightness variability. PMID:24443633

  8. Glaucoma and Driving Risk under Simulated Fog Conditions

    PubMed Central

    Diniz-Filho, Alberto; Boer, Erwin R.; Elhosseiny, Ahmed; Wu, Zhichao; Nakanishi, Masaki; Medeiros, Felipe A.

    2016-01-01

    Purpose We evaluate driving risk under simulated fog conditions in glaucoma and healthy subjects. Methods This cross-sectional study included 41 glaucoma patients and 25 age-matched healthy subjects who underwent driving simulation. Tests consisted of curve negotiation without and with fog preview at 30 m of distance and two controlled speeds (slow and fast). Inverse time-to-line crossing (invTLC) was used as metric to quantify risk; higher invTLC values indicating higher risk, as less time is available to avoid drifting out of the road. Piecewise regression models were used to investigate the relationship between differences in invTLC in fog and nonfog conditions and visual field loss. Results Glaucoma patients had greater increase in driving risk under fog compared to controls, as indicated by invTLC differences (0.490 ± 0.578 s−1 and 0.208 ± 0.106 s−1, respectively; P = 0.002). Mean deviation (MD) of the better eye was significantly associated with driving risk under fog, with a breakpoint of −9 dB identified by piecewise regression. For values below the breakpoint, each 1 dB lower MD of better eye was associated with 0.117 s−1 higher invTLC under fast speed (adjusted R2 = 57.9%; P < 0.001). Conclusions Glaucoma patients have a steeper increase in driving risk under fog conditions when compared to healthy subjects, especially when the severity of visual field damage falls below −9 dB of MD in the better eye. Translational Relevance By investigating the relationship between driving risk and disease severity breakpoint, this study may provide guidance to clinicians in recognizing glaucoma patients who may be unfit to drive in complex situations such as fog. PMID:27980878

  9. Fatigue and voluntary utilization of automation in simulated driving.

    PubMed

    Neubauer, Catherine; Matthews, Gerald; Langheim, Lisa; Saxby, Dyani

    2012-10-01

    A driving simulator was used to assess the impact on fatigue, stress, and workload of full vehicle automation that was initiated by the driver. Previous studies have shown that mandatory use of full automation induces a state of "passive fatigue" associated with loss of alertness. By contrast, voluntary use of automation may enhance the driver's perceptions of control and ability to manage fatigue. Participants were assigned to one of two experimental conditions, automation optional (AO) and nonautomation (NA), and then performed a 35 min, monotonous simulated drive. In the last 5 min, automation was unavailable and drivers were required to respond to an emergency event. Subjective state and workload were evaluated before and after the drive. Making automation available to the driver failed to alleviate fatigue and stress states induced by driving in monotonous conditions. Drivers who were fatigued prior to the drive were more likely to choose to use automation, but automation use increased distress, especially in fatigue-prone drivers. Drivers in the AO condition were slower to initiate steering responses to the emergency event, suggesting optional automation may be distracting. Optional, driver-controlled automation appears to pose the same dangers to task engagement and alertness as externally initiated automation. Drivers of automated vehicles may be vulnerable to fatigue that persists when normal vehicle control is restored. It is important to evaluate automated systems' impact on driver fatigue, to seek design solutions to the issue of maintaining driver engagement, and to address the vulnerabilities of fatigue-prone drivers.

  10. Medical resident driving simulator performance following a night on call.

    PubMed

    Ware, J Catesby; Risser, Mathew R; Manser, Thomas; Karlson, Karl H

    2006-01-01

    This study compared driving simulation performance after night call and after being off call in 22 medical residents and 1 medical student in a prospective within-subjects counterbalanced design. The results demonstrated an unexpected interaction between call and sex wherein men performed more poorly after night call than women as measured by lane variance and crash frequency. Secondary measures, including caffeine, actigraphy, and subjective total sleep time, did not differ between men and women. Collectively, results of this study and others suggest that medical residents are at risk when driving after a night on call and support the need for resident education to address sleep needs, consequences of sleep disruption, postcall recovery sleep, and countermeasures that may reduce residents' driving risks.

  11. An Exploratory Investigation: Are Driving Simulators Appropriate to Teach Pre-Driving Skills to Young Adults with Intellectual Disabilities?

    ERIC Educational Resources Information Center

    Brooks, Johnell O.; Mossey, Mary E.; Tyler, Peg; Collins, James C.

    2014-01-01

    Research examining driver training for young adults with intellectual disabilities has been limited since the 1970s. The current pilot and exploratory study investigated teaching pre-driving skills (i.e. lane keeping and speed maintenance) to young adults with intellectual disabilities using an interactive driving simulator to provide dynamic and…

  12. An Exploratory Investigation: Are Driving Simulators Appropriate to Teach Pre-Driving Skills to Young Adults with Intellectual Disabilities?

    ERIC Educational Resources Information Center

    Brooks, Johnell O.; Mossey, Mary E.; Tyler, Peg; Collins, James C.

    2014-01-01

    Research examining driver training for young adults with intellectual disabilities has been limited since the 1970s. The current pilot and exploratory study investigated teaching pre-driving skills (i.e. lane keeping and speed maintenance) to young adults with intellectual disabilities using an interactive driving simulator to provide dynamic and…

  13. Traffic and Driving Simulator Based on Architecture of Interactive Motion

    PubMed Central

    Paz, Alexander; Veeramisti, Naveen; Khaddar, Romesh; de la Fuente-Mella, Hanns; Modorcea, Luiza

    2015-01-01

    This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i) motion-based driving simulation, (ii) pedestrian simulation, (iii) motorcycling and bicycling simulation, and (iv) traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination. PMID:26491711

  14. Traffic and Driving Simulator Based on Architecture of Interactive Motion.

    PubMed

    Paz, Alexander; Veeramisti, Naveen; Khaddar, Romesh; de la Fuente-Mella, Hanns; Modorcea, Luiza

    2015-01-01

    This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i) motion-based driving simulation, (ii) pedestrian simulation, (iii) motorcycling and bicycling simulation, and (iv) traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination.

  15. Why do drivers maintain short headways in fog? A driving-simulator study evaluating feeling of risk and lateral control during automated and manual car following.

    PubMed

    Saffarian, M; Happee, R; Winter, J C F de

    2012-01-01

    Drivers in fog tend to maintain short headways, but the reasons behind this phenomenon are not well understood. This study evaluated the effect of headway on lateral control and feeling of risk in both foggy and clear conditions. Twenty-seven participants completed four sessions in a driving simulator: clear automated (CA), clear manual (CM), fog automated (FA) and fog manual (FM). In CM and FM, the drivers used the steering wheel, throttle and brake pedals. In CA and FA, a controller regulated the distance to the lead car, and the driver only had to steer. Drivers indicated how much risk they felt on a touchscreen. Consistent with our hypothesis, feeling of risk and steering activity were elevated when the lead car was not visible. These results might explain why drivers adopt short headways in fog. Practitioner Summary: Fog poses a serious road safety hazard. Our driving-simulator study provides the first experimental evidence to explain the role of risk-feeling and lateral control in headway reduction. These results are valuable for devising effective driver assistance and support systems.

  16. Both texting and eating are associated with impaired simulated driving performance.

    PubMed

    Alosco, Michael L; Spitznagel, Mary Beth; Fischer, Kimberly Hall; Miller, Lindsay A; Pillai, Vivek; Hughes, Joel; Gunstad, John

    2012-09-01

    Distracted driving is a known contributor to traffic accidents, and many states have banned texting while driving. However, little is known about the potential accident risk of other common activities while driving, such as eating. The objective of the current study was to examine the adverse impact of eating/drinking behavior relative to texting and nondistracted behaviors on a simulated driving task. A total of 186 participants were recruited from undergraduate psychology courses over 2 semesters at Kent State University. We utilized the Kent Multidimensional Assessment Driving Simulation (K-MADS) to compare simulated driving performance among participants randomly assigned to texting (N = 45), eating (N = 45), and control (N = 96) conditions. Multivariate analyses of variance (MANOVA) were conducted to examine between-group differences on simulated driving indices. MANOVA analyses indicated that groups differed in simulated driving performance, F(14, 366) = 7.70, P < .001. Both texting and eating produced impaired driving performance relative to controls, though these behaviors had approximately equal effect. Specifically, both texting and eating groups had more collisions, pedestrian strikes, and center line crossings than controls. In addition, the texting group had more road edge excursions than either eating or control participants and the eating group missed more stop signs than controls. These findings suggest that both texting and eating are associated with poorer simulated driving performance. Future work is needed to determine whether these findings generalize to real-world driving and the development of strategies to reduce distracted driving.

  17. EEG potentials predict upcoming emergency brakings during simulated driving

    NASA Astrophysics Data System (ADS)

    Haufe, Stefan; Treder, Matthias S.; Gugler, Manfred F.; Sagebaum, Max; Curio, Gabriel; Blankertz, Benjamin

    2011-10-01

    Emergency braking assistance has the potential to prevent a large number of car crashes. State-of-the-art systems operate in two stages. Basic safety measures are adopted once external sensors indicate a potential upcoming crash. If further activity at the brake pedal is detected, the system automatically performs emergency braking. Here, we present the results of a driving simulator study indicating that the driver's intention to perform emergency braking can be detected based on muscle activation and cerebral activity prior to the behavioural response. Identical levels of predictive accuracy were attained using electroencephalography (EEG), which worked more quickly than electromyography (EMG), and using EMG, which worked more quickly than pedal dynamics. A simulated assistance system using EEG and EMG was found to detect emergency brakings 130 ms earlier than a system relying only on pedal responses. At 100 km h-1 driving speed, this amounts to reducing the braking distance by 3.66 m. This result motivates a neuroergonomic approach to driving assistance. Our EEG analysis yielded a characteristic event-related potential signature that comprised components related to the sensory registration of a critical traffic situation, mental evaluation of the sensory percept and motor preparation. While all these components should occur often during normal driving, we conjecture that it is their characteristic spatio-temporal superposition in emergency braking situations that leads to the considerable prediction performance we observed.

  18. EEG potentials predict upcoming emergency brakings during simulated driving.

    PubMed

    Haufe, Stefan; Treder, Matthias S; Gugler, Manfred F; Sagebaum, Max; Curio, Gabriel; Blankertz, Benjamin

    2011-10-01

    Emergency braking assistance has the potential to prevent a large number of car crashes. State-of-the-art systems operate in two stages. Basic safety measures are adopted once external sensors indicate a potential upcoming crash. If further activity at the brake pedal is detected, the system automatically performs emergency braking. Here, we present the results of a driving simulator study indicating that the driver's intention to perform emergency braking can be detected based on muscle activation and cerebral activity prior to the behavioural response. Identical levels of predictive accuracy were attained using electroencephalography (EEG), which worked more quickly than electromyography (EMG), and using EMG, which worked more quickly than pedal dynamics. A simulated assistance system using EEG and EMG was found to detect emergency brakings 130 ms earlier than a system relying only on pedal responses. At 100 km h(-1) driving speed, this amounts to reducing the braking distance by 3.66 m. This result motivates a neuroergonomic approach to driving assistance. Our EEG analysis yielded a characteristic event-related potential signature that comprised components related to the sensory registration of a critical traffic situation, mental evaluation of the sensory percept and motor preparation. While all these components should occur often during normal driving, we conjecture that it is their characteristic spatio-temporal superposition in emergency braking situations that leads to the considerable prediction performance we observed.

  19. The effect of different delineator post configurations on driver speed in night-time traffic: a driving simulator study.

    PubMed

    Nygårdhs, Sara; Lundkvist, Sven-Olof; Andersson, Jan; Dahlbäck, Nils

    2014-11-01

    The aim of the study was to investigate how different delineator post configurations affect driver speed in night-time traffic. In addition, the potential speed effect of introducing a secondary task was investigated. The study was carried out in a car simulator on a road stretch including straight road sections as well as curves with different radii. Fourteen drivers participated in the study and the results show that absence of delineator posts leads to reduced speed. However, provided that there are delineator posts continuously present along the road, the overall driver speed is basically the same, regardless of the spacing between the delineator posts. The results also imply that to reduce driver speed in curves with small radius, using more compact spacing of posts in these curves as compared to in curves with a larger radius, could be a potential strategy. Additionally, the speed reducing effect of a secondary task was only prevailing where the task was initiated. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Main drive selection for the Windstorm Simulation Center

    SciTech Connect

    Lacy, J.M.; Earl, J.S.

    1998-02-01

    Operated by the Partnership for Natural Disaster Reduction, the Windstorm Simulation Center (WSC) will be a structural test center dedicated to studying the performance of civil structural systems subjected to hurricanes, tornadoes, and other storm winds. Within the WSC, a bank of high-power fans, the main drive, will produce the high velocity wind necessary to reproduce these storms. Several options are available for the main drive, each with advantages and liabilities. This report documents a study to identify and evaluate all candidates available, and to select the most promising system such that the best possible combination of real-world performance attributes is achieved at the best value. Four broad classes of candidate were identified: electric motors, turbofan aircraft engines, turboshaft aircraft engines, and turboshaft industrial engines. Candidate systems were evaluated on a basis of technical feasibility, availability, power, installed cost, and operating cost.

  1. Simulated Driving Changes in Young Adults with ADHD Receiving Mixed Amphetamine Salts Extended Release and Atomoxetine

    ERIC Educational Resources Information Center

    Kay, Gary G.; Michaels, M. Alex; Pakull, Barton

    2009-01-01

    Background: Psychostimulant treatment may improve simulated driving performance in young adults with attention-deficit/hyperactivity disorder (ADHD). Method: This was a randomized, double-blind, placebo-controlled, crossover study of simulated driving performance with mixed amphetamine salts--extended release (MAS XR) 50 mg/day (Cohort 1) and…

  2. Alcohol consumption for simulated driving performance: A systematic review.

    PubMed

    Rezaee-Zavareh, Mohammad Saeid; Salamati, Payman; Ramezani-Binabaj, Mahdi; Saeidnejad, Mina; Rousta, Mansoureh; Shokraneh, Farhad; Rahimi-Movaghar, Vafa

    2017-06-01

    Alcohol consumption can lead to risky driving and increase the frequency of traffic accidents, injuries and mortalities. The main purpose of our study was to compare simulated driving performance between two groups of drivers, one consumed alcohol and the other not consumed, using a systematic review. In this systematic review, electronic resources and databases including Medline via Ovid SP, EMBASE via Ovid SP, PsycINFO via Ovid SP, PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINHAL) via EBSCOhost were comprehensively and systematically searched. The randomized controlled clinical trials that compared simulated driving performance between two groups of drivers, one consumed alcohol and the other not consumed, were included. Lane position standard deviation (LPSD), mean of lane position deviation (MLPD), speed, mean of speed deviation (MSD), standard deviation of speed deviation (SDSD), number of accidents (NA) and line crossing (LC) were considered as the main parameters evaluating outcomes. After title and abstract screening, the articles were enrolled for data extraction and they were evaluated for risk of biases. Thirteen papers were included in our qualitative synthesis. All included papers were classified as high risk of biases. Alcohol consumption mostly deteriorated the following performance outcomes in descending order: SDSD, LPSD, speed, MLPD, LC and NA. Our systematic review had troublesome heterogeneity. Alcohol consumption may decrease simulated driving performance in alcohol consumed people compared with non-alcohol consumed people via changes in SDSD, LPSD, speed, MLPD, LC and NA. More well-designed randomized controlled clinical trials are recommended. Copyright © 2017. Production and hosting by Elsevier B.V.

  3. Driver's visual attention as a function of driving experience and visibility. Using a driving simulator to explore drivers' eye movements in day, night and rain driving.

    PubMed

    Konstantopoulos, Panos; Chapman, Peter; Crundall, David

    2010-05-01

    Road crashes are the main cause of death of young people in the developed world. The reasons that cause traffic crashes are numerous; however, most researchers agree that a lack of driving experience is one of the major contributing factors. In addition it has been demonstrated that environmental factors such as driving during night and rain increases the risk of a crash. Both of these factors may be related to drivers' visual search strategies that become more efficient with increased experience. In the present study we recorded the eye movements of driving instructors and learner drivers while they drove three virtual routes that included day, night and rain routes in a driving simulator. The results showed that driving instructors had an increased sampling rate, shorter processing time and broader scanning of the road than learner drivers. This broader scanning of the road could be possibly explained by the mirror inspection pattern which revealed that driving instructors fixated more on the side mirrors than learner drivers. Also it was found that poor visibility conditions, especially rain, decrease the effectiveness of drivers' visual search. The lack of interaction between driving experience and visibility suggests that some aspects of visual search are affected by general rather than situation specific driving experience. The present findings support the effect of driving experience in modifying eye movement strategies. The high accident risk of night and rain driving could be partly explained by the decrement in visual search strategies during these conditions. Finally it is argued that the use of driving simulators can provide valuable insights regarding driving safety.

  4. Creating pedestrian crash scenarios in a driving simulator environment.

    PubMed

    Chrysler, Susan T; Ahmad, Omar; Schwarz, Chris W

    2015-01-01

    In 2012 in the United States, pedestrian injuries accounted for 3.3% of all traffic injuries but, disproportionately, pedestrian fatalities accounted for roughly 14% of traffic-related deaths (NHTSA 2014 ). In many other countries, pedestrians make up more than 50% of those injured and killed in crashes. This research project examined driver response to crash-imminent situations involving pedestrians in a high-fidelity, full-motion driving simulator. This article presents a scenario development method and discusses experimental design and control issues in conducting pedestrian crash research in a simulation environment. Driving simulators offer a safe environment in which to test driver response and offer the advantage of having virtual pedestrian models that move realistically, unlike test track studies, which by nature must use pedestrian dummies on some moving track. An analysis of pedestrian crash trajectories, speeds, roadside features, and pedestrian behavior was used to create 18 unique crash scenarios representative of the most frequent and most costly crash types. For the study reported here, we only considered scenarios where the car is traveling straight because these represent the majority of fatalities. We manipulated driver expectation of a pedestrian both by presenting intersection and mid-block crossing as well as by using features in the scene to direct the driver's visual attention toward or away from the crossing pedestrian. Three visual environments for the scenarios were used to provide a variety of roadside environments and speed: a 20-30 mph residential area, a 55 mph rural undivided highway, and a 40 mph urban area. Many variables of crash situations were considered in selecting and developing the scenarios, including vehicle and pedestrian movements; roadway and roadside features; environmental conditions; and characteristics of the pedestrian, driver, and vehicle. The driving simulator scenarios were subjected to iterative testing to

  5. Gender Differences in Alcohol Impairment of Simulated Driving Performance and Driving-Related Skills

    PubMed Central

    Miller, Melissa A.; Weafer, Jessica; Fillmore, Mark T.

    2009-01-01

    Aims: Considerable laboratory research indicates that moderate doses of alcohol impair a broad range of skilled activities related to driving performance in young adults. Although laboratory studies show that the intensity of impairment is generally dependent on the blood alcohol concentration, some reviews of this literature suggest that women might be more sensitive to the impairing effects of alcohol than men. The present study tested this hypothesis. Methods: Drawing on data from previous experiments in our laboratory, we compared men and women in terms of the degree to which a challenge dose of alcohol (0.65 g/kg) impaired their simulated driving performance and measures of three separate behavioral and cognitive functions important to driving performance: motor coordination, speed of information processing and information-processing capacity. Results: Alcohol significantly impaired all aspects of performance. Moreover, women displayed greater impairment than men on all behavioral tests and also reported higher levels of subjective intoxication compared with men. Conclusions: Both biological and social–cultural factors have been implicated in gender differences in the behavioral responses to alcohol. The current evidence of heightened sensitivity to alcohol in women highlights the need for better understanding the biological and environmental factors underlying this gender difference. PMID:19786725

  6. Application of a Multi-Objective Network Model to a Combat Simulation Game: The Drive on Metz Case Study

    DTIC Science & Technology

    2014-03-27

    referred to as a combat simulation, the battle area is commonly divided into some sort of grid [17]. This structure lends itself to easy modeling as a...network, where each grid area can be represented as a node in the network. As a player 1 plans a strategy and plays the game, many successive decisions...forces and the other the defending German forces. The game is played on a map that represents the vicinity of the city of Metz, covering an area of

  7. Drive mechanism for production of simulated human breath

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G.; Hendricks, C. M.; Lambert, J. W.; Morison, W. B.

    1972-01-01

    Simulated breath drive mechanism was developed as subsystem to breathing metabolic simulator. Mechanism reproduces complete range of human breath rate, breath depth, and breath waveform, as well as independently controlled functional residual capacity. Mechanism was found capable of simulating various individual human breathing characteristics without any changes of parts.

  8. Action prediction based on anticipatory brain potentials during simulated driving

    NASA Astrophysics Data System (ADS)

    Khaliliardali, Zahra; Chavarriaga, Ricardo; Gheorghe, Lucian Andrei; Millán, José del R.

    2015-12-01

    Objective. The ability of an automobile to infer the driver’s upcoming actions directly from neural signals could enrich the interaction of the car with its driver. Intelligent vehicles fitted with an on-board brain-computer interface able to decode the driver’s intentions can use this information to improve the driving experience. In this study we investigate the neural signatures of anticipation of specific actions, namely braking and accelerating. Approach. We investigated anticipatory slow cortical potentials in electroencephalogram recorded from 18 healthy participants in a driving simulator using a variant of the contingent negative variation (CNV) paradigm with Go and No-go conditions: count-down numbers followed by ‘Start’/‘Stop’ cue. We report decoding performance before the action onset using a quadratic discriminant analysis classifier based on temporal features. Main results. (i) Despite the visual and driving related cognitive distractions, we show the presence of anticipatory event related potentials locked to the stimuli onset similar to the widely reported CNV signal (with an average peak value of -8 μV at electrode Cz). (ii) We demonstrate the discrimination between cases requiring to perform an action upon imperative subsequent stimulus (Go condition, e.g. a ‘Red’ traffic light) versus events that do not require such action (No-go condition; e.g. a ‘Yellow’ light); with an average single trial classification performance of 0.83 ± 0.13 for braking and 0.79 ± 0.12 for accelerating (area under the curve). (iii) We show that the centro-medial anticipatory potentials are observed as early as 320 ± 200 ms before the action with a detection rate of 0.77 ± 0.12 in offline analysis. Significance. We show for the first time the feasibility of predicting the driver’s intention through decoding anticipatory related potentials during simulated car driving with high recognition rates.

  9. Advanced simulation model for IPM motor drive with considering phase voltage and stator inductance

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Myung; Park, Hyun-Jong; Lee, Ju

    2016-10-01

    This paper proposes an advanced simulation model of driving system for Interior Permanent Magnet (IPM) BrushLess Direct Current (BLDC) motors driven by 120-degree conduction method (two-phase conduction method, TPCM) that is widely used for sensorless control of BLDC motors. BLDC motors can be classified as SPM (Surface mounted Permanent Magnet) and IPM motors. Simulation model of driving system with SPM motors is simple due to the constant stator inductance regardless of the rotor position. Simulation models of SPM motor driving system have been proposed in many researches. On the other hand, simulation models for IPM driving system by graphic-based simulation tool such as Matlab/Simulink have not been proposed. Simulation study about driving system of IPMs with TPCM is complex because stator inductances of IPM vary with the rotor position, as permanent magnets are embedded in the rotor. To develop sensorless scheme or improve control performance, development of control algorithm through simulation study is essential, and the simulation model that accurately reflects the characteristic of IPM is required. Therefore, this paper presents the advanced simulation model of IPM driving system, which takes into account the unique characteristic of IPM due to the position-dependent inductances. The validity of the proposed simulation model is validated by comparison to experimental and simulation results using IPM with TPCM control scheme.

  10. Passenger and Cell Phone Conversations in Simulated Driving

    ERIC Educational Resources Information Center

    Drews, Frank A.; Pasupathi, Monisha; Strayer, David L.

    2008-01-01

    This study examines how conversing with passengers in a vehicle differs from conversing on a cell phone while driving. We compared how well drivers were able to deal with the demands of driving when conversing on a cell phone, conversing with a passenger, and when driving without any distraction. In the conversation conditions, participants were…

  11. Passenger and Cell Phone Conversations in Simulated Driving

    ERIC Educational Resources Information Center

    Drews, Frank A.; Pasupathi, Monisha; Strayer, David L.

    2008-01-01

    This study examines how conversing with passengers in a vehicle differs from conversing on a cell phone while driving. We compared how well drivers were able to deal with the demands of driving when conversing on a cell phone, conversing with a passenger, and when driving without any distraction. In the conversation conditions, participants were…

  12. Evaluation of Driver Stress Using Motor-vehicle Driving Simulator

    NASA Astrophysics Data System (ADS)

    Deguchi, Mitsuo; Wakasugi, Junichi; Ikegami, Tatsuya; Nanba, Shinji; Yamaguchi, Masaki

    This paper proposes a method for evaluating driver stress using a motor-vehicle driving simulator and a biomarker as an index of stress. Software has been developed, which can deliberately control driving tasks, in addition to analyzing driving information, such as frequency of the use of accelerator and/or brakes and the degree of deviation from the driving course. Sympathetic nervous activity was noninvasively evaluated using a hand-held monitor of salivary amylase activity, which chemically measured a biomarker every few minutes. Using healthy 20 female adults, the appropriateness of the proposed method was evaluated in vivo. The experimental results showed that the driving stress might be caused to the drivers in only 20 minutes by adding more severe driving tasks than normally experienced by the subjects without endangering them. Furthermore, the result indicate that frequent measurements of sympathetic nervous activity were possible without putting the subjects under restraint by using salivary amylase activity as the index.

  13. Further development of a commercial driving simulation for research in occupational medicine.

    PubMed

    Muttray, Axel; Breitinger, Anais; Goetze, Elisabeth; Schnupp, Thomas; Geissler, Britta; Kaufmann, Thomas; Golz, Martin; Letzel, Stephan

    2013-12-01

    The purpose of this study was to refine a commercial car driving simulation for occupational research. As the effects of ethanol on driving behavior are well established, we choose alcohol as a test compound to investigate the performance of subjects during simulation. We programmed a night driving scenario consisting of monotonous highway and a rural road on a Foerst F10-P driving simulator. Twenty healthy men, 19-30 years, participated in a pilot study. Subjects were screened for simulator sickness, followed by training on the simulator one hour in total. Experiments were performed in the morning on a separate day. Participants were randomized into either an alcoholized or a control group. All subjects drove two courses consisting of highway and rural road and were sober for the first course. During a 1 h break the ethanol group drank an alcoholic beverage to yield 0.06% blood alcohol concentration (BAC). Generalized linear mixed models were used to analyze the influence of alcohol on driving performance. Among others, independent variables were Simulator Sickness Questionnaire scores and subjective sleepiness. Subjects did not experience simulator sickness during the experiments. Mean BAC before the second test drive was 0.065% in the mildly intoxicated group. There was no clear-cut difference in the number of crashes between 2 groups. BAC of 0.1% would deteriorate mean braking reaction time by 237 ms (SE = 112, p < 0.05). Ethanol slightly impaired the tracking in the right-hand curves (p = 0.058). Braking reaction time improved by 86 ms (SE = 36, p < 0.05) for the second test drive, indicating a learning effect. In sum, a clear ethanol effect was observed in the driving simulation. This simulation seems suitable for occupational research and produces little simulator sickness. Controlling for possible learning effects is recommended in driving simulation studies.

  14. Electric Drive Study. Volume 1

    DTIC Science & Technology

    1987-12-21

    necessary and identify by block number) FIELD j GROUP SUB-GROUP IElectric Drives, Motors , Homopolar Motors , Induction Motof’s, I-u I ’Propulsion Systems...Planetary Final Drive (19.5 Ton) ( Homopolar ) . . . 80 5-32. Integrated Motor /Final Drive ....... ............ 82 5-33. Configuration II, 19.5 Ton...98 5-43. Homopolar Motor System Efficiency Map .... ......... 101 5-44. Potential Rotary Field Exciter Configuratio ......... 104 5-45

  15. Oil strategies benefits over different driving cycles using numerical simulation

    NASA Astrophysics Data System (ADS)

    Sara, Hanna; Chalet, David; Cormerais, Mickaël; Hetet, Jean-François

    2017-08-01

    95 g/km is the allowed quantity of CO2 emission normalized to NEDC to be set in 2020. In addition, NEDC will be replaced by more severe driving cycles and will be united worldwide. To respond to those criteria, automotive industries are working on every possible field. Thermal management has been proved to be effective in reducing fuel consumption. Cold start is a primordial reason of overconsumption, as the engine highest efficiency is at its optimal temperature. At cold start, the engine's oil is at its lowest temperature and thus its higher viscosity level. A high viscosity oil generates more friction, which is one of the most important heat losses in the engine. In this paper, hot oil storage is studied. Numerical simulations on GT-suite model were done. The model consists of a 4-cylinder turbocharged Diesel engine using a storage volume of 1 liter of hot oil. Ambient temperature variation were taken into consideration as well as different driving cycles. Furthermore, different configurations of the thermal strategy (multifunction oil sump) were proposed and evaluated. Lubricant temperature and viscosity profiles are presented in the article as well as fuel consumption savings for different configurations, driving cycles and ambient temperatures.

  16. Simulated driving and brain imaging: combining behavior, brain activity, and virtual reality.

    PubMed

    Carvalho, Kara N; Pearlson, Godfrey D; Astur, Robert S; Calhoun, Vince D

    2006-01-01

    Virtual reality in the form of simulated driving is a useful tool for studying the brain. Various clinical questions can be addressed, including both the role of alcohol as a modulator of brain function and regional brain activation related to elements of driving. We reviewed a study of the neural correlates of alcohol intoxication through the use of a simulated-driving paradigm and wished to demonstrate the utility of recording continuous-driving behavior through a new study using a programmable driving simulator developed at our center. Functional magnetic resonance imaging data was collected from subjects while operating a driving simulator. Independent component analysis (ICA) was used to analyze the data. Specific brain regions modulated by alcohol, and relationships between behavior, brain function, and alcohol blood levels were examined with aggregate behavioral measures. Fifteen driving epochs taken from two subjects while also recording continuously recorded driving variables were analyzed with ICA. Preliminary findings reveal that four independent components correlate with various aspects of behavior. An increase in braking while driving was found to increase activation in motor areas, while cerebellar areas showed signal increases during steering maintenance, yet signal decreases during steering changes. Additional components and significant findings are further outlined. In summary, continuous behavioral variables conjoined with ICA may offer new insight into the neural correlates of complex human behavior.

  17. Using a driving simulator to identify older drivers at inflated risk of motor vehicle crashes.

    PubMed

    Lee, Hoe C; Lee, Andy H; Cameron, Don; Li-Tsang, Cecilia

    2003-01-01

    To develop appropriate assessment criteria to measure the performance of older drivers using an interactive PC-based driving simulator, and to determine which measures were associated with the occurrence of motor-vehicle crash. One hundred and twenty-nine older drivers residing in a metropolitan city volunteered to participate in this retrospective cohort study. Using the driving simulator, appropriate driving tasks were devised to test the older drivers, whose performances were assessed by 10 reliable assessment criteria. Logistic regression analysis was then undertaken to determine those criteria that influence the self-reported crash outcome. As expected, driving skill of older drivers was found to decline with age. Over 60% of the sample participants reported having at least one motor-vehicle crash during the past year. Adjusting for age in a logistic regression analysis, the cognitive abilities associated with the crash occurrence were working memory, decision making under pressure of time, and confidence in driving at high speed. The findings of this retrospective study indicated those individuals at inflated risk of vehicle crashes could be identified using the PC-based interactive driving simulator. Prospective studies need to be undertaken to determine whether the driving simulator can predict future crash events. This study demonstrated an economical driving simulator approach to screen out problematic or unsafe older drivers before a more detailed but expensive road test is considered.

  18. Simulations of time-dependent drive asymmetries for shock ignition

    NASA Astrophysics Data System (ADS)

    Loomis, Eric; Dodd, Evan; Cobble, James; Marinak, Marty; Sauppe, Joshua

    2016-10-01

    Shock Ignition (SI) is an extension of conventional inertial confinement fusion (ICF) where a strong shock heats low temperature, but highly compressed, deuterium-tritium fuel to ignition conditions. The conditions for maximum pressure amplification by the ignitor shock have been predicted in one-dimensional geometry where shock heating is most efficient. In real experiments, asymmetries in the flow field almost always take on 2- and 3-dimensional structure. To study the degradation in heating efficiency of the ignitor shock when interacting with asymmetric rebounding shocks and multi-dimensional flow we have performed a series of HYDRA simulations that use the indirect drive high foot design of Dittrich et al.. In our simulations we truncated the radiation drive to peak at 270 eV and used the remaining energy to directly irradiate the capsule with a spherical laser source to create the ignitor shock. Legendre mode asymmetries were applied to the radiation field at different times during implosion of the capsule producing fuel and rebounding shock asymmetries that significantly reduced the ignitor efficiency. We will present how the heating is reduced for asymmetries in the pulse foot and peak.

  19. Effects of marijuana on equilibrium, psychomotor performance, and simulated driving.

    PubMed

    Liguori, A; Gatto, C P; Robinson, J H

    1998-11-01

    Delta-9-tetrahydrocannabinol (THC) is frequently found in the blood of drivers involved in automobile accidents, and marijuana use has been associated with impaired field sobriety test performance. The present study used a within-subject design to compare the effects of marijuana (0, 1.77, or 3.95% THC) on equilibrium and simulated driving. Ten marijuana users (seven men, three women) smoked one marijuana cigarette at the beginning of each session. Then 2 min later, they began a 60-min test battery that included subjective effects scales, a computerized test of body sway, a rapid judgment task and brake latency measurement in a driving simulator, critical flicker fusion (CFF), and a choice reaction time task (CRT). Self-report ratings of 'high' and 'drug potency' increased comparably following both active doses. The high, but not the low, dose significantly increased body sway. The high dose also marginally increased brake latency by a mean of 55 ms (P < 0.10), which is comparable to an increase in stopping distance of nearly 5 feet at 60 mph Judgment, CFF, and CRT scores did not differ across dose conditions. The equilibrium and brake latency data with 3.95% THC are similar to prior results in our laboratory in participants with breath alcohol concentrations near 0.05%.

  20. Alcohol Effects on Simulated Driving in Frequent and Infrequent Binge Drinkers

    PubMed Central

    Bernosky-Smith, Kimberly A.; Shannon, Erin E.; Roth, Alicia J.; Liguori, Anthony

    2011-01-01

    Objective Compared to non-bingers, binge drinkers are more likely to drive while intoxicated. The extent to which binge frequency impacts confidence in driving and subsequent driving impairment is unknown. This study compared the effects of an experimenter-delivered alcohol binge on subjective impairment and simulated driving ability in female High and Low Frequency bingers. Methods Female drinkers were assigned to High Frequency (n=30) or Low Frequency (n=30) binge groups based on their Alcohol Use Questionnaire responses. At 30-minute intervals within a two-hour period, participants received either a placebo drink (n=15 per group) or a 0.2 g/kg dose of alcohol (n=15 per group; cumulative dose 0.8 g/kg). Self-reported impairment, driving confidence, and simulated driving were then measured. Results Self-reported confidence in driving was significantly lower after alcohol than after placebo in Low Frequency but not High Frequency bingers. Self-reported impairment and collisions during simulated driving were significantly greater after alcohol than after placebo in both Low Frequency and High Frequency bingers. Conclusions The impairing effects of a single alcohol binge on driving ability in females are not influenced by binge frequency. However, high binge frequency may be associated with a less cautious approach to post-binge driving. PMID:21542027

  1. Simulated long-term driving performance before and after uvulopalatopharyngoplasty.

    PubMed

    Haraldsson, P O; Carenfelt, C; Persson, H E; Sachs, C; Törnros, J

    1991-01-01

    To investigate whether automobile drivers with the clinical features of sleep apnea syndrome (SAS) perform worse than controls in a simulated long-term test drive, and to see if their driving improves after uvulopalatopharyngoplasty (UPPP), 15 male drivers with SAS, suffering from sleep spells whilst driving, and 10 matched controls without a history of SAS or hypersomnia at the wheel were tested in an advanced driving simulator. Brake reaction time, lateral position deviation and off-road episodes were measured during a 90-min rural drive at twilight conditions. The clinical evaluation was made by a questionnaire scoring symptoms of snoring, sleep disturbances and diurnal sleepiness before and after surgery. Before UPPP the patient group showed impaired performance in all three effect measures compared to controls. UPPP resulted in improved reaction time performance (average mean improvement: 0.5 s, average 90th percentile improvement 0.8 s). Furthermore, 12 of the 15 patients reported a marked improvement regarding sleepiness whilst driving. For these clinically successful cases the number of off-road episodes decreased substantially. We conclude that most patients improve their long-term driving performance as a result of UPPP.

  2. Sex differences in the effects of marijuana on simulated driving performance.

    PubMed

    Anderson, Beth M; Rizzo, Matthew; Block, Robert I; Pearlson, Godfrey D; O'Leary, Daniel S

    2010-03-01

    In the United States, one in six teenagers has driven under the influence of marijuana. Driving under the influence of marijuana and alcohol is equally prevalent, despite the fact that marijuana use is less common than alcohol use. Much of the research examining the effects of marijuana on driving performance was conducted in the 1970s and led to equivocal findings. During that time, few studies included women and driving simulators were rudimentary. Further, the potency of marijuana commonly used recreationally has increased. This study examined sex differences in the acute effects of marijuana on driving performance using a realistic, validated driving simulator. Eighty-five subjects (n = 50 males, 35 females) participated in this between-subjects, double-blind, placebo controlled study. In addition to an uneventful, baseline segment of driving, participants were challenged with collision avoidance and distracted driving scenarios. Under the influence of marijuana, participants decreased their speed and failed to show expected practice effects during a distracted drive. No differences were found during the baseline driving segment or collision avoidance scenarios. No differences attributable to sex were observed. This study enhances the current literature by identifying distracted driving and the integration of prior experience as particularly problematic under the influence of marijuana.

  3. Sex Differences in the Effects of Marijuana on Simulated Driving Performance†

    PubMed Central

    Anderson, Beth M.; Rizzo, Matthew; Block, Robert I.; Pearlson, Godfrey D.; O'Leary, Daniel S.

    2011-01-01

    In the United States, one in six teenagers has driven under the influence of marijuana. Driving under the influence of marijuana and alcohol is equally prevalent, despite the fact that marijuana use is less common than alcohol use. Much of the research examining the effects of marijuana on driving performance was conducted in the 1970s and led to equivocal findings. During that time, few studies included women and driving simulators were rudimentary. Further, the potency of marijuana commonly used recreationally has increased. This study examined sex differences in the acute effects of marijuana on driving performance using a realistic, validated driving simulator. Eighty-five subjects (n = 50 males, 35 females) participated in this between-subjects, double-blind, placebo controlled study. In addition to an uneventful, baseline segment of driving, participants were challenged with collision avoidance and distracted driving scenarios. Under the influence of marijuana, participants decreased their speed and failed to show expected practice effects during a distracted drive. No differences were found during the baseline driving segment or collision avoidance scenarios. No differences attributable to sex were observed. This study enhances the current literature by identifying distracted driving and the integration of prior experience as particularly problematic under the influence of marijuana. PMID:20464803

  4. Design of an immersive simulator for assisted power wheelchair driving.

    PubMed

    Devigne, Louise; Babel, Marie; Nouviale, Florian; Narayanan, Vishnu K; Pasteau, Francois; Gallien, Philippe

    2017-07-01

    Driving a power wheelchair is a difficult and complex visual-cognitive task. As a result, some people with visual and/or cognitive disabilities cannot access the benefits of a power wheelchair because their impairments prevent them from driving safely. In order to improve their access to mobility, we have previously designed a semi-autonomous assistive wheelchair system which progressively corrects the trajectory as the user manually drives the wheelchair and smoothly avoids obstacles. Developing and testing such systems for wheelchair driving assistance requires a significant amount of material resources and clinician time. With Virtual Reality technology, prototypes can be developed and tested in a risk-free and highly flexible Virtual Environment before equipping and testing a physical prototype. Additionally, users can "virtually" test and train more easily during the development process. In this paper, we introduce a power wheelchair driving simulator allowing the user to navigate with a standard wheelchair in an immersive 3D Virtual Environment. The simulation framework is designed to be flexible so that we can use different control inputs. In order to validate the framework, we first performed tests on the simulator with able-bodied participants during which the user's Quality of Experience (QoE) was assessed through a set of questionnaires. Results show that the simulator is a promising tool for future works as it generates a good sense of presence and requires rather low cognitive effort from users.

  5. Driving simulator for speed research on two-lane rural roads.

    PubMed

    Bella, Francesco

    2008-05-01

    The paper reports on a validation study of the interactive fixed-base driving simulator of Inter-University Research Center for Road Safety (CRISS) that was effectuated in order to verify the CRISS driving simulator's usefulness at a tool for speed research on two-lane rural roads. Speeds were recorded at eleven measurement sites with different alignment configurations on a two-lane rural road near Rome. The real world was reproduced in the CRISS driving simulator. Forty drivers drove the simulator. The results of the comparative and statistical analysis established the relative validity and also revealed that absolute validity was obtained in nine measurements sites. Only in two non-demanding configurations, were the speeds in simulator significantly higher than those recorded in the field. In these sites the mean speed in simulator was equal to or greater than 94 km/h. For these configurations, the higher speeds recorded in simulator appeared to stem from the different risk perception on the simulated road as opposed to that on the real road. The study's results should be considered for driving speed behavior research, in which simulator equipment with similar features of the CRISS driving simulator is used.

  6. Drive Electric Vermont Case Study

    SciTech Connect

    Wagner, Fred; Roberts, Dave; Francfort, Jim; White, Sera

    2016-03-01

    Currently in the United States, the heavy majority of plug-in electric vehicle (PEV) sales have been in highly conducive, selected, metropolitan areas; opposed to more broad distribution across the country. The U.S. Department of Energy’s EV Everywhere Grand Challenge is looking carefully at the barriers and opportunities that exist to enable small and midsize communities to partake in the PEV market and benefit from the economic and environmental advantages of PEVs. In order to gain insight into these challenges and barriers, DOE selected a success story (i.e., Drive Electric Vermont) as the subject of this case study, as the state of Vermont is tied with Detroit, Michigan in having the highest percentage of 2014 (most recent complete data) PEV registrations for cold weather U.S. cities and has seen more than a sixfold increase in charging stations over the last three years. The overall objective of this case study was to use the lessons learned from Drive Electric Vermont to determine what activities are most effective at encouraging acquisitions of PEVs and deployment of charging infrastructure in small to midsize communities, prioritizing and sequencing their implementation, identifying robust means for extrapolation, and applying this understanding to other small to midsize communities across the nation. The Drive Electric Vermont Program was formed in 2012 with a goal of increasing the use of electrified transportation in Vermont through policy development, education and outreach, and infrastructure development. The Drive Electric Vermont Program can be broadly broken into four components: (1) strategic planning/leadership, (2) stakeholder/partnership development, (3) education and outreach, and (4) incentives. The early phases of the program focused heavily on strategic planning, and stakeholder and partnership development, followed by a transition to education and outreach activities, charging infrastructure development, and grant and incentive programs

  7. Numerical Simulation of Indirect-Drive Tracer Diagnostic Experiments

    NASA Astrophysics Data System (ADS)

    Macfarlane, J. J.; Cohen, D. H.; Wang, P.; Jaanimagi, P.; Back, C. A.; Landen, O. L.; Turner, R. E.; Oertel, J. A.; Nash, T. J.

    1998-11-01

    We have performed indirect-drive experiments at the OMEGA (U. Rochester) and NOVA (LLNL) laser facilities to study the use of tracer emission and absorption spectroscopy in characterizing radiatively-driven materials. In these experiments, thin ( ~ 3000 Åthick) tracer layers of KCl, KF, and NaCl were embedded in ~ 50 -- 100 μm-thick Al and Ge-doped CH ``witness plates'' which were attached to the side of cylindrical Au hohlraums. In most cases the hohlraums were irradiated with 12 -- 25 TW, 1 ns square laser pulses, which generate a high-TR radiation drive (TR ≈ 200 eV). In some experiments, shaped laser pulses were used. The radiation wave burns into the witness plate, heating the tracer to temperatures of 100 -- 200 eV. In emission spectroscopy experiments performed using a Hettrick soft x-ray spectrometer,(Back et al., and Cohen et al. APS DPP Meeting 1997.) (hν ~ 300 - 900 eV; λ/Δλ ~ 500), K, Cl, and F emission lines were observed above the continuum of the Al witness plate. Absorption spectroscopy experiments at OMEGA are scheduled to be performed in August 1998.(Cohen et al., this meeting.) We will present results from numerical simulations of these experiments, utilizing non-LTE collisional-radiative, radiation-hydrodynamics, and 3-D view factor codes.

  8. Assessing Cognitive Ability and Simulator-Based Driving Performance in Poststroke Adults.

    PubMed

    Blane, Alison; Lee, Hoe C; Falkmer, Torbjörn; Willstrand, Tania Dukic

    2017-01-01

    Driving is an important activity of daily living, which is increasingly relied upon as the population ages. It has been well-established that cognitive processes decline following a stroke and these processes may influence driving performance. There is much debate on the use of off-road neurological assessments and driving simulators as tools to predict driving performance; however, the majority of research uses unlicensed poststroke drivers, making the comparability of poststroke adults to that of a control group difficult. It stands to reason that in order to determine whether simulators and cognitive assessments can accurately assess driving performance, the baseline should be set by licenced drivers. Therefore, the aim of this study was to assess differences in cognitive ability and driving simulator performance in licensed community-dwelling poststroke drivers and controls. Two groups of licensed drivers (37 poststroke and 43 controls) were assessed using several cognitive tasks and using a driving simulator. The poststroke adults exhibited poorer cognitive ability; however, there were no differences in simulator performance between groups except that the poststroke drivers demonstrated less variability in driver headway. The application of these results as a prescreening toolbox for poststroke drivers is discussed.

  9. Driving simulator performance and psychomotor functions of schizophrenic patients treated with antipsychotics.

    PubMed

    Brunnauer, Alexander; Laux, Gerd; Zwick, Sarah

    2009-12-01

    The objective of the study is to compare schizophrenic inpatients under antipsychotic monotherapy regarding simulated driving behaviour and psychomotor functions related to driving ability. Schizophrenic inpatients (n = 80) were tested before discharge to outpatient treatment. Data were collected with the computerized Act & React Testsystem and the Wiener Testsystem measuring visual perception, reaction time, attention, vigilance and stress-tolerance. Besides, patients underwent various driving simulations on a static driving simulator (FT-SR 200). Before discharge to outpatient treatment, about 25% of schizophrenic patients must be considered as severely impaired with respect to driving skills. Differences between treatment groups could be shown both in psychomotor measures and in driving simulator performance with a better test performance of patients treated with atypical antipsychotics. Controlling for age, psychopathologic symptoms and extrapyramidal signs, differences in psychomotor measures were most pronounced in concentration and vigilance. As mental disorders itself pose an increased risk of accidents, counselling patients with respect to differential effects of antipsychotic treatment is of great relevance. In addition to psychomotor tests computer-simulated driving seems to be a useful tool in assessing traffic safety under pharmacologic treatment.

  10. Assessing Cognitive Ability and Simulator-Based Driving Performance in Poststroke Adults

    PubMed Central

    Falkmer, Torbjörn; Willstrand, Tania Dukic

    2017-01-01

    Driving is an important activity of daily living, which is increasingly relied upon as the population ages. It has been well-established that cognitive processes decline following a stroke and these processes may influence driving performance. There is much debate on the use of off-road neurological assessments and driving simulators as tools to predict driving performance; however, the majority of research uses unlicensed poststroke drivers, making the comparability of poststroke adults to that of a control group difficult. It stands to reason that in order to determine whether simulators and cognitive assessments can accurately assess driving performance, the baseline should be set by licenced drivers. Therefore, the aim of this study was to assess differences in cognitive ability and driving simulator performance in licensed community-dwelling poststroke drivers and controls. Two groups of licensed drivers (37 poststroke and 43 controls) were assessed using several cognitive tasks and using a driving simulator. The poststroke adults exhibited poorer cognitive ability; however, there were no differences in simulator performance between groups except that the poststroke drivers demonstrated less variability in driver headway. The application of these results as a prescreening toolbox for poststroke drivers is discussed. PMID:28559646

  11. Experimental research on the effectiveness and adaptability of speed reduction markings in downhill sections on urban roads: a driving simulation study.

    PubMed

    Ding, Han; Zhao, Xiaohua; Rong, Jian; Ma, Jianming

    2015-02-01

    The objective of this paper is to test the effectiveness and adaptability of speed reduction markings (SRMs) in downhill sections on urban roads with distinct roadway grades. Empirical data including vehicle speed and acceleration were collected in a driving simulator. Subjective questionnaires were conducted, and two indexes - the relative speed difference and standard deviation of acceleration - were developed to evaluate the effectiveness and adaptability of SRMs. Meanwhile, the effectiveness of driving simulator related to different road alignments and types of SRMs has been validated through a field test. Results of subjective questionnaires showed that the majority of subjects had no feelings of nervousness, but they were affected by SRMs while driving through downhill sections in all four scenarios (i.e., downhill sections with vertical grades of 3, 2, 1.5 and 1%). In terms of vehicle speed and acceleration, the results of the analysis of variance (ANOVA) and the contrast analysis (S-N-K method) indicated that SRMs were significantly effective when roadway grades of downgrade sections were 1.5, 2 and 3%, while transverse speed reduction markings (TSRMs) had significantly worse adaptability (P<0.05). Therefore, this research recommends that TSRMs could be placed in downhill sections with roadway grades of 1.5 or 2%; longitudinal speed reduction markings (LSRMs) could be placed in downhill sections with a roadway grade of 3%. Whether SRMs are placed in downhill sections with a roadway grade of 1% would depend on other factors such as financial issues and crash records, which are not considered in this paper.

  12. Validation of the driver behaviour questionnaire using behavioural data from an instrumented vehicle and high-fidelity driving simulator.

    PubMed

    Helman, S; Reed, N

    2015-02-01

    Data from two previously published studies were used to examine the correlations between scores on the violation, error and lapse sub-scales of the driver behaviour questionnaire, and observed driving speed. One dataset utilised data from an instrumented vehicle, which recorded driver speed on bends on a rural road. The other utilised data from a driving simulator study. Generally in both datasets the DBQ violation subscale was associated with objectively-measured speed, while the error and lapse sub-scales were not. These findings are consistent with the idea that the DBQ is a valid measure of observed behaviour in real driving (its original intended use) and also in simulated driving. The fact that associations were the same in real and simulated driving lends further support to the relative validity of driving simulation. The need for larger and more focused studies examining the role of different motivations in different driving situations is discussed.

  13. Simulated Driving Performance of Adults with ADHD: Comparisons with Alcohol Intoxication

    PubMed Central

    Weafer, Jessica; Camarillo, Daniel; Fillmore, Mark T.; Milich, Richard; Marczinski, Cecile A.

    2015-01-01

    Previous research has demonstrated that adults with ADHD are more likely to experience driving-related problems, which suggests that they may exhibit poorer driving performance. However, direct experimental evidence of this hypothesis is limited. The current study involved two experiments that evaluated driving performance in adults with ADHD in terms of the types of driving decrements typically associated with alcohol intoxication. Experiment 1 compared the simulated driving performance of 15 adults with ADHD to 23 adult control participants, who performed the task both while sober and intoxicated. Results showed that sober adults with ADHD exhibited decrements in driving performance compared to sober controls, and that the profile of impairment for the sober ADHD group did in fact resemble that of intoxicated drivers at the BAC level for legally impaired driving in the United States. Driving impairment of the intoxicated individuals was characterized by greater deviation of lane position, faster and more abrupt steering maneuvers, and increased speed variability. Experiment 2 was a dose-challenge study in which 8 adults with ADHD and 8 controls performed the driving simulation task under three doses of alcohol: 0.65 g/kg, 0.45 g/kg, and 0.0 g/kg (placebo). Results showed that driving performance in both groups was impaired in response to alcohol, and that individuals with ADHD exhibited generally poorer driving performance than did controls across all dose conditions. Together the findings provide compelling evidence to suggest that the cognitive and behavioral deficits associated with ADHD might impair driving performance in such a manner as to resemble that of an alcohol intoxicated driver. Moreover, alcohol might impair the performance of drivers with ADHD in an additive fashion that could considerably compromise their driving skill even at blood alcohol concentrations below the legal limit. PMID:18540785

  14. Simulated driving performance of adults with ADHD: comparisons with alcohol intoxication.

    PubMed

    Weafer, Jessica; Camarillo, Daniel; Fillmore, Mark T; Milich, Richard; Marczinski, Cecile A

    2008-06-01

    Previous research has demonstrated that adults with attention deficit/hyperactivity disorder (ADHD) are more likely to experience driving-related problems, which suggests that they may exhibit poorer driving performance. However, direct experimental evidence of this hypothesis is limited. The current study involved 2 experiments that evaluated driving performance in adults with ADHD in terms of the types of driving decrements typically associated with alcohol intoxication. Experiment 1 compared the simulated driving performance of 15 adults with ADHD to 23 adult control participants, who performed the task both while sober and intoxicated. Results showed that sober adults with ADHD exhibited decrements in driving performance compared to sober controls, and that the profile of impairment for the sober ADHD group did in fact resemble that of intoxicated drivers at the blood alcohol concentration level for legally impaired driving in the United States. Driving impairment of the intoxicated individuals was characterized by greater deviation of lane position, faster and more abrupt steering maneuvers, and increased speed variability. Experiment 2 was a dose-challenge study in which 8 adults with ADHD and 8 controls performed the driving simulation task under 3 doses of alcohol: 0.65g/kg, 0.45g/kg, and 0.0g/kg (placebo). Results showed that driving performance in both groups was impaired in response to alcohol, and that individuals with ADHD exhibited generally poorer driving performance than did controls across all dose conditions. Together the findings provide compelling evidence to suggest that the cognitive and behavioral deficits associated with ADHD might impair driving performance in such a manner as to resemble that of an alcohol intoxicated driver. Moreover, alcohol might impair the performance of drivers with ADHD in an additive fashion that could considerably compromise their driving skill even at blood alcohol concentrations below the legal limit.

  15. Drive-train simulator for a fuel cell hybrid vehicle

    NASA Astrophysics Data System (ADS)

    Brown, Darren; Alexander, Marcus; Brunner, Doug; Advani, Suresh G.; Prasad, Ajay K.

    The model formulation, development process, and experimental validation of a new vehicle powertrain simulator called LFM (Light, Fast, and Modifiable) are presented. The existing powertrain simulators were reviewed and it was concluded that there is a need for a new, easily modifiable simulation platform that will be flexible and sufficiently robust to address a variety of hybrid vehicle platforms. First, the structure and operating principle of the LFM simulator are presented, followed by a discussion of the subsystems and input/output parameters. Finally, a validation exercise is presented in which the simulator's inputs were specified to represent the University of Delaware's fuel cell hybrid transit vehicle and "driven" using an actual drive cycle acquired from it. Good agreement between the output of the simulator and the physical data acquired by the vehicle's on-board sensors indicates that the simulator constitutes a powerful and reliable design tool.

  16. Particle simulation of intense electron cyclotron heating and beat-wave current drive

    SciTech Connect

    Cohen, B.I.

    1987-10-12

    High-power free-electron lasers make new methods possible for heating plasmas and driving current in toroidal plasmas with electromagnetic waves. We have undertaken particle simulation studies with one and two dimensional, relativistic particle simulation codes of intense pulsed electron cyclotron heating and beat-wave current drive. The particle simulation methods here are conventional: the algorithms are time-centered, second-order-accurate, explicit, leap-frog difference schemes. The use of conventional methods restricts the range of space and time scales to be relatively compact in the problems addressed. Nevertheless, experimentally relevant simulations have been performed. 10 refs., 2 figs.

  17. Optical correction reduces simulator sickness in a driving environment.

    PubMed

    Bridgeman, Bruce; Blaesi, Sabine; Campusano, Richard

    2014-12-01

    We propose and test a method to reduce simulator sickness. Prolonged work in driving simulators often leads to nausea and other symptoms summarized as simulator sickness. Visual/vestibular mismatches are a frequently addressed cause; we investigate another possibility, mismatch between actual distance to a screen and depicted distances in the simulator's graphics. Drivers negotiated a figure-8 course in a photorealistic simulator. They reported discomfort and vection every 10 minutes up to 40 min. A correction group wore optometric test frames with + 1.75 diopter lenses and prisms to converge parallel lines of sight on a screen 56 cm from the driver's eyes, preserving the normal accommodative convergence-to-accommodation (AC/A) ratio. A control group wore neutral lenses in the same test frames. In other experiments head tilt simulated vestibular experience on curves. The optical correction significantly reduced simulator sickness measured on a 10-point discomfort scale, where I is no problem and 10 is about to vomit. Vection ratings were similar for correction and control groups. Some drivers failed to complete the course because of high discomfort ratings, crashes, or other causes. Head tilt in the direction opposite each curve while wearing the correction did not affect discomfort, while tilt in the same direction as each curve made simulator sickness worse. Optical corrections can significantly reduce simulator sickness, though they do not eliminate it. Head tilt while driving is not recommended. Application: Simple optical corrections in spectacle frames, easily purchased at any optical facility, should be used in screen-based driving simulators. Strength of the correction depends on distance from the driver to the screen.

  18. The impact of immediate or delayed feedback on driving behaviour in a simulated Pay-As-You-Drive system.

    PubMed

    Dijksterhuis, Chris; Lewis-Evans, Ben; Jelijs, Bart; de Waard, Dick; Brookhuis, Karel; Tucha, Oliver

    2015-02-01

    Pay-As-You-Drive (PAYD) insurance links an individual's driving behaviour to the insurance fee that they pay, making car insurance more actuarially accurate. The best known PAYD insurance format is purely mileage based and is estimated to reduce accidents by about 15% (Litman, 2011). However, these benefits could be further enhanced by incorporating a wider range of driving behaviours, such as lateral and longitudinal accelerations and speeding behaviour, thereby stimulating not only a safe but also an eco-friendly driving style. Currently, feedback on rewards and driver behaviour is mostly provided through a web-based interface, which is presented temporally separated from driving. However, providing immediate feedback within the vehicle itself could elicit more effect. To investigate this hypothesis, two groups of 20 participants drove with a behavioural based PAYD system in a driving simulator and were provided with either delayed feedback through a website, or immediate feedback through an in-car interface, allowing them to earn up to €6 extra. To be clear, every participant in the web group did actually view their feedback during the one week between sessions. Results indicate clear driving behaviour improvements for both PAYD groups as compared to baseline rides and an equal sized control group. After both PAYD groups had received feedback, the initial advantage of the in-car group was reduced substantially. Taken together with usability ratings and driving behaviours in specific situations these results show a moderate advantage of using immediate in-car feedback. However, the study also showed that under conditions of feedback certainty, the effectiveness of delayed feedback approaches that of immediate feedback as compared to a naïve control group.

  19. Assessing the Driver’s Current Level of Working Memory Load with High Density Functional Near-infrared Spectroscopy: A Realistic Driving Simulator Study

    PubMed Central

    Unni, Anirudh; Ihme, Klas; Jipp, Meike; Rieger, Jochem W.

    2017-01-01

    Cognitive overload or underload results in a decrease in human performance which may result in fatal incidents while driving. We envision that driver assistive systems which adapt their functionality to the driver’s cognitive state could be a promising approach to reduce road accidents due to human errors. This research attempts to predict variations of cognitive working memory load levels in a natural driving scenario with multiple parallel tasks and to reveal predictive brain areas. We used a modified version of the n-back task to induce five different working memory load levels (from 0-back up to 4-back) forcing the participants to continuously update, memorize, and recall the previous ‘n’ speed sequences and adjust their speed accordingly while they drove for approximately 60 min on a highway with concurrent traffic in a virtual reality driving simulator. We measured brain activation using multichannel whole head, high density functional near-infrared spectroscopy (fNIRS) and predicted working memory load level from the fNIRS data by combining multivariate lasso regression and cross-validation. This allowed us to predict variations in working memory load in a continuous time-resolved manner with mean Pearson correlations between induced and predicted working memory load over 15 participants of 0.61 [standard error (SE) 0.04] and a maximum of 0.8. Restricting the analysis to prefrontal sensors placed over the forehead reduced the mean correlation to 0.38 (SE 0.04), indicating additional information gained through whole head coverage. Moreover, working memory load predictions derived from peripheral heart rate parameters achieved much lower correlations (mean 0.21, SE 0.1). Importantly, whole head fNIRS sampling revealed increasing brain activation in bilateral inferior frontal and bilateral temporo-occipital brain areas with increasing working memory load levels suggesting that these areas are specifically involved in workload-related processing. PMID

  20. Driving Plasmaspheric Electron Density Simulations During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    De Pascuale, S.; Kletzing, C.; Jordanova, V.; Goldstein, J.; Wygant, J. R.; Thaller, S. A.

    2015-12-01

    We test global convection electric field models driving plasmaspheric electron density simulations (RAM-CPL) during geomagnetic storms with in situ measurements provided by the Van Allen Probes (RBSP). RAM-CPL is the cold plasma component of the ring-current atmosphere interactions suite (RAM-SCB) and describes the evolution of plasma density in the magnetic equatorial plane near Earth. Geomagnetic events observed by the RBSP satellites in different magnetic local time (MLT) sectors enable a comparison of local asymmetries in the input electric field and output densities of these simulations. Using a fluid MHD approach, RAM-CPL reproduces core plasmaspheric densities (L<4) to less than 1 order of magnitude difference. Approximately 80% of plasmapause crossings, defined by a low-density threshold, are reproduced to within a mean radial difference of 0.6 L. RAM-CPL, in conjunction with a best-fit driver, can be used in other studies as an asset to predict density conditions in locations distant from RBSP orbits of interest.

  1. The Characteristics of Sleepiness During Real Driving at Night—A Study of Driving Performance, Physiology and Subjective Experience

    PubMed Central

    Sandberg, David; Anund, Anna; Fors, Carina; Kecklund, Göran; Karlsson, Johan G.; Wahde, Mattias; Åkerstedt, Torbjörn

    2011-01-01

    Study Objectives: Most studies of sleepy driving have been carried out in driving simulators. A few studies of real driving are available, but these have used only a few sleepiness indicators. The purpose of the present study was to characterize sleepiness in several indicators during real driving at night, compared with daytime driving. Design: Participants drove 55 km (at 90km/h) on a 9-m-wide rural highway in southern Sweden. Daytime driving started at 09:00 or 11:00 (2 groups) and night driving at 01:00 or 03:00 (balanced design). Setting: Instrumented car on a real road in normal traffic. Participants: Eighteen participants drawn from the local driving license register. Interventions: Daytime and nighttime drives. Measurement and Results: The vehicle was an instrumented car with video monitoring of the edge of the road and recording of the lateral position and speed. Electroencephalography and electrooculography were recorded, together with ratings of sleepiness every 5 minutes. Pronounced effects of night driving were seen for subjective sleepiness, electroencephalographic indicators of sleepiness, blink duration, and speed. Also, time on task showed significant effects for subjective sleepiness, blink duration, lane position, and speed. Sleepiness was highest toward the end of the nighttime drive. Night driving caused a leftward shift in lateral position and a reduction of speed. The latter two findings, as well as the overall pattern of sleepiness indicators, provide new insights into the effects of night driving. Conclusion: Night driving is associated with high levels of subjective, electrophysiologic, and behavioral sleepiness. Citation: Sandberg D; Anund A; Fors C; Kecklund G; Karlsson JG; Wahde M; Åkerstedt T. The characteristics of sleepiness during real driving at night—a study of driving performance, physiology and subjective experience. SLEEP 2011;34(10):1317-1325. PMID:21966063

  2. Simulations of NOVA direct-drive hydrodynamics experiments

    SciTech Connect

    Weber, S.V,; Glendinning, S.G.

    1991-04-15

    Directly driven Rayleigh-Taylor instability growth experiments being performed on NOVA have been simulated using the computer code, LASNEX. Foils with single-wavelength imposed surface perturbations have been driven with a single beam of 0.53 {mu}m light, employing smoothing by spectral dispersion (SSD). In addition to simulating foils with imposed surface perturbations, we have simulated flat foils driven by beams with time-dependent intensity modulation resulting from the NOVA implementation of SSD. These simulations show the development of large amplitude modulation of the target from residual intensity nonuniformities. Structure seeded by beam nonuniformity would overwhelm modulation resulting from imposed surface perturbations of sub-micron initial amplitude, but is predicted to develop sufficiently slowly that we expect to observe growth of perturbations with initial amplitudes of several microns. In other NOVA experiments, flat foils with an embedded brominated spectroscopic tracer layer are used in infer mass ablation rates. SSD drive is predicted to yield ablation rates in better agreement with 1-D simulations than drive from a beam with random phase plates (RPP) alone. Simulations of foils driven with RPP beams show enhanced ablation rates because modulation of the ablation front increases its surface area. Line emission from the seed is first seen at cold spots in the beam, which create protruding spikes at the ablation front. Simulation results will be compared with early experimental data. 5 refs., 14 figs.

  3. The effect of d-methamphetamine on simulated driving performance.

    PubMed

    Silber, Beata Y; Croft, Rodney J; Downey, Luke A; Papafotiou, Katherine; Camfield, David A; Stough, Con

    2012-03-01

    Methamphetamine is considered to be one of the most popularly abused drugs by drivers; however, its exact effect on driving and driving behaviour has yet to be thoroughly investigated. This being despite methamphetamine's increased prevalence in injured and deceased drivers. Twenty healthy recreational illicit stimulant users (10 male and 10 female), aged between 21 and 32 years (mean = 25.4 years, SD = 3.3 years) attended two testing sessions involving oral consumption of 0.42 mg/kg d-methamphetamine or a matching placebo. The drug administration was counter-balanced, double-blind, and medically supervised. At each session driving, performance was assessed 2.5 h post drug administration. d-methamphetamine (0.42 mg/kg) did not significantly impair overall simulated driving performance 2.5 h post drug administration. At the individual driving variable level, participants in the d-methamphetamine condition were observed to be driving slower when an emergency situation occurred (T = 44, p < 0.05), but interestingly, participants in both conditions recorded average speeds in excess of the speed limit (100 km/h) when the emergency situations occurred. The d-methamphetamine condition did also produce four times more infringements where participants did not stop at red traffic light in comparison to the placebo, but this effect was only evident at a trend level (T = 7, p = 0.11). The findings presented herein suggest that d-methamphetamine administered at the levels supplied did not impair driving performance in a manner consistent with epidemiological evidence. Further research is certainly required to elucidate the effects of various doses of methamphetamine, alone and in combination with other legal and illicit substances. Copyright © 2012 John Wiley & Sons, Ltd.

  4. Simulation-Based Design of a Rotatory SMA Drive

    NASA Astrophysics Data System (ADS)

    Dilthey, Sascha; Meier, Horst

    2009-08-01

    The design and optimization of a rotatory drive powered by shape memory alloy (SMA) actuators is described in this paper. SMA actuators used in technical applications are parameterized by the use of trial-and-error methods, because there is a lack of computer-aided design tools for this active material. A numerical modeling approach was developed to design and optimize the geometry and the load and heating conditions of SMA actuators in a technical system to achieve a good dynamic and a high reliability. The shape memory effect used in most technical systems is the extrinsic two way effect (2WE). This effect can be simulated with the numerical model which was implemented in MATLAB/SIMULINK. The focus of the model is on the activation behavior of the SMA actuator, which defines its rate of heating and cooling. Different load conditions and various actuator geometries and shapes, e.g. wire or spring actuator, are simulated by the calculation of the energetic balance of the whole system. The numerical model can be used to simulate time variant heating currents in order to obtain an optimal system performance. The model was used to design a rotatory SMA-drive system, which is based on the moving concept of a wave drive gear set. In contrast to the conventional system, which is driven by an electric motor, the SMA drive consists of a strain wave gear and SMA wire actuators that are applied circularly to generate a rotatory movement. Special characteristics of this drive system are a high torque density and a high positioning accuracy.

  5. 3-D MHD Simulation of Oscillating Field Current Drive

    NASA Astrophysics Data System (ADS)

    Ebrahimi, F.; Prager, S. C.; Wright, J. C.

    2000-10-01

    Oscillating Field Current Drive (OFCD) is a proposed low frequency steady-state current drive technique for the Reversed Field Pinch (RFP). In OFCD toroidal and poloidal oscillating electric fields are applied with 90^circ phase difference to inject magnetic helicity. In the present work, the 3-D nonlinear, resistive MHD code DEBS is used to simulate OFCD in relaxed RFP plasmas. The present simulations are at high Lundquist number S=10^5 and low spect ratio R/a=1.5. The physics issues investigated are the response of background magnetic fluctuations to the oscillating fields, the relative contributions of the tearing mode dynamo and the oscillating fields to the current profile, and the sustainment and control of the steady-state current profile. Initial results with low amplitude oscillating fields show the expected increase in magnetic helicity and current. Results with higher amplitude will also be presented.

  6. Comparison of driving simulator performance with real driving after alcohol intake: a randomised, single blind, placebo-controlled, cross-over trial.

    PubMed

    Helland, Arne; Jenssen, Gunnar D; Lervåg, Lone-Eirin; Westin, Andreas Austgulen; Moen, Terje; Sakshaug, Kristian; Lydersen, Stian; Mørland, Jørg; Slørdal, Lars

    2013-04-01

    The purpose of this study was to establish and validate a driving simulator method for assessing drug effects on driving. To achieve this, we used ethanol as a positive control, and examined whether ethanol affects driving performance in the simulator, and whether these effects are consistent with performance during real driving on a test track, also under the influence of ethanol. Twenty healthy male volunteers underwent a total of six driving trials of 1h duration; three in an instrumented vehicle on a closed-circuit test track that closely resembled rural Norwegian road conditions, and three in the simulator with a driving scenario modelled after the test track. Test subjects were either sober or titrated to blood alcohol concentration (BAC) levels of 0.5g/L and 0.9g/L. The study was conducted in a randomised, cross-over, single-blind fashion, using placebo drinks and placebo pills as confounders. The primary outcome measure was standard deviation of lateral position (SDLP; "weaving"). Eighteen test subjects completed all six driving trials, and complete data were acquired from 18 subjects in the simulator and 10 subjects on the test track, respectively. There was a positive dose-response relationship between higher ethanol concentrations and increases in SDLP in both the simulator and on the test track (p<0.001 for both). In the simulator, this dose-response was evident already after 15min of driving. SDLP values were higher and showed a larger inter-individual variability in the simulator than on the test track. Most subjects displayed a similar relationship between BAC and SDLP in the simulator and on the test track; however, a few subjects showed striking dissimilarities, with very high SDLP values in the simulator. This may reflect the lack of perceived danger in the simulator, causing reckless driving in a few test subjects. Overall, the results suggest that SDLP in the driving simulator is a sensitive measure of ethanol impaired driving. The comparison

  7. Simulations of ICRF-fast wave current drive on DIIID

    SciTech Connect

    Ehst, D.A.

    1990-06-01

    Self-consistent calculations of MHD equilibria, generated by fast wave current drive and including the bootstrap effect, were done to guide and anticipate the results of upcoming experiments on the DIIID tokamak. The simulations predict that 2 MW of ICRF power is more than adequate to create several hundred kiloamperes in steady state; the total current increases with the temperature and density of the target plasma. 12 refs., 12 figs., 1 tab.

  8. Driving with Hemianopia, II: Lane Position and Steering in a Driving Simulator

    PubMed Central

    Mandel, Aaron J.; Goldstein, Robert B.; Peli, Eli

    2010-01-01

    Purpose. The hypothesis that drivers with homonymous hemianopia (HH) would take a lane position that increased the safety margin on their blind side was tested with a driving simulator. Methods. Twelve participants with HH (six right HH and six left; nine men; mean age, 50 years; range 31–72), and 12 matched current drivers with normal vision (NV) each completed approximately 120 minutes of simulator driving. Lane position and steering stability were evaluated for specific road segment types (straight segments, curves, and turns) in city and rural undivided highway driving. Results. The drivers with right HH held a lane position significantly (P = 0.001) to the left of NV drivers on the straight road segments and to a lesser extent on the curves. The drivers with left HH had a lane position similar to that of the NV drivers on straights and curves, but followed a significantly (P = 0.005) more rightward path on the left turns. Conclusions. The results support the hypothesis that drivers with HH take a lane position that increases the safety margin on their blind side; however, absolute lane position varies as the steering maneuver and location of the risk from oncoming traffic change with road segment type. PMID:20671269

  9. Using collective variables to drive molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Fiorin, Giacomo; Klein, Michael L.; Hénin, Jérôme

    2013-12-01

    A software framework is introduced that facilitates the application of biasing algorithms to collective variables of the type commonly employed to drive massively parallel molecular dynamics (MD) simulations. The modular framework that is presented enables one to combine existing collective variables into new ones, and combine any chosen collective variable with available biasing methods. The latter include the classic time-dependent biases referred to as steered MD and targeted MD, the temperature-accelerated MD algorithm, as well as the adaptive free-energy biases called metadynamics and adaptive biasing force. The present modular software is extensible, and portable between commonly used MD simulation engines.

  10. Simulations of EBW current drive and power deposition in the WEGA Stellarator

    SciTech Connect

    Preinhaelter, J.; Urban, J.; Vahala, L.; Vahala, G.

    2009-11-26

    The WEGA stellarator is well suited for fundamental electron Bernstein wave (EBW) studies. Heating and current drive experiments at 2.45 GHz and 28 GHz, carried out in WEGA's low temperature, steady state overdense plasmas, were supported by intensive modelling. We employ our AMR (Antenna-Mode-conversion-Ray-tracing) code to calculate the O-X-EBW conversion efficiency with a full-wave equation solver, while the power deposition and current drive profiles using ray tracing. Several phenomena have been studied and understood. Particularly, EBW current drive was theoretically predicted and experimentally detected at 2.45 GHz. Simulations confirmed the presence of two (cold and hot) electron components and the resonant behaviour of the EBW power deposition and its dependence on the magnetic field configuration. Furthermore, the code is used to predict the 28 GHz heating and current drive performance and to simulate EBW emission spectra.

  11. Alcohol effects on simulated driving performance and self-perceptions of impairment in DUI offenders

    PubMed Central

    Van Dyke, Nicholas; Fillmore, Mark T.

    2014-01-01

    Drivers with a history of driving under the influence (DUI) of alcohol self-report heightened impulsivity and display reckless driving behaviors as indicated by increased rates of vehicle crashes, moving violations, and traffic tickets. Such poor behavioral self-regulation could also increase sensitivity to the disruptive effects of alcohol on driving performance. The present study examined the degree to which DUI drivers display an increased sensitivity to the acute impairing effects of alcohol on simulated driving performance and overestimate their driving fitness following alcohol consumption. Adult drivers with a history of DUI and a demographically-matched group of drivers with no history of DUI (controls) were tested following a 0.65 g/kg alcohol and a placebo. Results indicated that alcohol impaired several measures of driving performance and there was no difference between DUI offenders and controls in these impairments. However, following alcohol DUI drivers self-reported a greater ability and willingness to drive compared with controls. These findings indicate that drivers with a history of DUI might perceive themselves as more fit to drive after drinking which could play an important role in their decisions to drink and drive. PMID:25347077

  12. Alcohol effects on simulated driving performance and self-perceptions of impairment in DUI offenders.

    PubMed

    Van Dyke, Nicholas; Fillmore, Mark T

    2014-12-01

    Drivers with a history of driving under the influence (DUI) of alcohol self-report heightened impulsivity and display reckless driving behaviors as indicated by increased rates of vehicle crashes, moving violations, and traffic tickets. Such poor behavioral self-regulation could also increase sensitivity to the disruptive effects of alcohol on driving performance. The present study examined the degree to which DUI drivers display an increased sensitivity to the acute impairing effects of alcohol on simulated driving performance and overestimate their driving fitness following alcohol consumption. Adult drivers with a history of DUI and a demographically matched group of drivers with no history of DUI (controls) were tested following a 0.65 g/kg alcohol and a placebo. Results indicated that alcohol impaired several measures of driving performance, and there was no difference between DUI offenders and controls in these impairments. However, following alcohol, DUI drivers self-reported a greater ability and willingness to drive compared with controls. These findings indicate that drivers with a history of DUI might perceive themselves as more fit to drive after drinking, which could play an important role in their decisions to drink and drive. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  13. Detecting and Quantifying Mind Wandering during Simulated Driving.

    PubMed

    Baldwin, Carryl L; Roberts, Daniel M; Barragan, Daniela; Lee, John D; Lerner, Neil; Higgins, James S

    2017-01-01

    Mind wandering is a pervasive threat to transportation safety, potentially accounting for a substantial number of crashes and fatalities. In the current study, mind wandering was induced through completion of the same task for 5 days, consisting of a 20-min monotonous freeway-driving scenario, a cognitive depletion task, and a repetition of the 20-min driving scenario driven in the reverse direction. Participants were periodically probed with auditory tones to self-report whether they were mind wandering or focused on the driving task. Self-reported mind wandering frequency was high, and did not statistically change over days of participation. For measures of driving performance, participant labeled periods of mind wandering were associated with reduced speed and reduced lane variability, in comparison to periods of on task performance. For measures of electrophysiology, periods of mind wandering were associated with increased power in the alpha band of the electroencephalogram (EEG), as well as a reduction in the magnitude of the P3a component of the event related potential (ERP) in response to the auditory probe. Results support that mind wandering has an impact on driving performance and the associated change in driver's attentional state is detectable in underlying brain physiology. Further, results suggest that detecting the internal cognitive state of humans is possible in a continuous task such as automobile driving. Identifying periods of likely mind wandering could serve as a useful research tool for assessment of driver attention, and could potentially lead to future in-vehicle safety countermeasures.

  14. Driving error and anxiety related to iPod mp3 player use in a simulated driving experience.

    PubMed

    Harvey, Ashley R; Carden, Randy L

    2009-08-01

    Driver distraction due to cellular phone usage has repeatedly been shown to increase the risk of vehicular accidents; however, the literature regarding the use of other personal electronic devices while driving is relatively sparse. It was hypothesized that the usage of an mp3 player would result in an increase in not only driving error while operating a driving simulator, but driver anxiety scores as well. It was also hypothesized that anxiety scores would be positively related to driving errors when using an mp3 player. 32 participants drove through a set course in a driving simulator twice, once with and once without an iPod mp3 player, with the order counterbalanced. Number of driving errors per course, such as leaving the road, impacts with stationary objects, loss of vehicular control, etc., and anxiety were significantly higher when an iPod was in use. Anxiety scores were unrelated to number of driving errors.

  15. MHD simulation of RF current drive in MST

    NASA Astrophysics Data System (ADS)

    Hendries, E. R.; Anderson, J. K.; Diem, S.; Forest, C. B.; Harvey, R. W.; Reusch, J. A.; Seltzman, A. H.; Sovinec, C. R.

    2014-02-01

    Auxiliary heating and current drive using RF waves such as the electron Bernstein wave (EBW) promises to advance the performance of the reversed field pinch (RFP). In previous computational work [1], a hypothetical edge-localized current drive is shown to suppress the tearing activity which governs the macroscopic transport properties of the RFP. The ideal conditions for tearing stabilization include a reduced toroidal induction, and precise width and radial position of the Gaussian-shaped external current drive. In support of the EBW experiment on the Madison Symmetric Torus, an integrated modeling scheme now incorporates ray tracing and Fokker-Plank predictions of auxiliary current into single fluid MHD. Simulations at low Lundquist number (S ˜ 104) generally agree with the previous work; significantly more burdensome simulations at MST-like Lundquist number (S ˜ 3×106) show unexpected results. The effect on nonlinearly saturated current profile by a particular RF-driven external force decreases in magnitude and widens considerably as the Lundquist number increases toward experimental values. Simulations reproduce the periodic current profile relaxation events observed in experiment (sawteeth) in the absence of current profile control. Reduction of the tearing mode amplitudes is still observable; however, reduction is limited to periods between the large bursts of magnetic activity at each sawtooth. The sawtoothing pattern persists with up to 10 MW of externally applied RF power. Periods with prolonged low tearing amplitude are predicted with a combination of external current drive and a reduced toroidal loop voltage, consistent with previous conclusions. Finally, the resistivity profile is observed to have a strong effect on the optimal externally driven current profile for mode stabilization.

  16. MHD simulation of RF current drive in MST

    SciTech Connect

    Hendries, E. R.; Anderson, J. K.; Forest, C. B.; Reusch, J. A.; Seltzman, A. H.; Sovinec, C. R.; Diem, S.; Harvey, R. W.

    2014-02-12

    Auxiliary heating and current drive using RF waves such as the electron Bernstein wave (EBW) promises to advance the performance of the reversed field pinch (RFP). In previous computational work [1], a hypothetical edge-localized current drive is shown to suppress the tearing activity which governs the macroscopic transport properties of the RFP. The ideal conditions for tearing stabilization include a reduced toroidal induction, and precise width and radial position of the Gaussian-shaped external current drive. In support of the EBW experiment on the Madison Symmetric Torus, an integrated modeling scheme now incorporates ray tracing and Fokker-Plank predictions of auxiliary current into single fluid MHD. Simulations at low Lundquist number (S ∼ 10{sup 4}) generally agree with the previous work; significantly more burdensome simulations at MST-like Lundquist number (S ∼ 3×10{sup 6}) show unexpected results. The effect on nonlinearly saturated current profile by a particular RF-driven external force decreases in magnitude and widens considerably as the Lundquist number increases toward experimental values. Simulations reproduce the periodic current profile relaxation events observed in experiment (sawteeth) in the absence of current profile control. Reduction of the tearing mode amplitudes is still observable; however, reduction is limited to periods between the large bursts of magnetic activity at each sawtooth. The sawtoothing pattern persists with up to 10 MW of externally applied RF power. Periods with prolonged low tearing amplitude are predicted with a combination of external current drive and a reduced toroidal loop voltage, consistent with previous conclusions. Finally, the resistivity profile is observed to have a strong effect on the optimal externally driven current profile for mode stabilization.

  17. Daytime Sleepiness and Driving Performance in Patients with Obstructive Sleep Apnea: Comparison of the MSLT, the MWT, and a Simulated Driving Task

    PubMed Central

    Pizza, Fabio; Contardi, Sara; Mondini, Susanna; Trentin, Lino; Cirignotta, Fabio

    2009-01-01

    Study Objectives: To test the reliability of a driving-simulation test for the objective measurement of daytime alertness compared with the Multiple Sleep Latency Test (MSLT) and with the Maintenance of Wakefulness Test (MWT), and to test the ability to drive safely, in comparison with on-road history, in the clinical setting of untreated severe obstructive sleep apnea. Design: N/A. Setting: Sleep laboratory. Patients or Participants: Twenty-four patients with severe obstructive sleep apnea and reported daytime sleepiness varying in severity (as measured by the Epworth Sleepiness Scale). Interventions: N/A. Measurements and Results: Patients underwent MSLT and MWT coupled with 4 sessions of driving-simulation test on 2 different days randomly distributed 1 week apart. Simulated-driving performance (in terms of lane-position variability and crash occurrence) was correlated with sleep latency on the MSLT and more significantly on the MWT, showing a predictive validity toward the detection of sleepy versus alert patients with obstructive sleep apnea. In addition, patients reporting excessive daytime sleepiness or a history of car crashes showed poorer performances on the driving simulator. Conclusions: A simulated driving test is a suitable tool for objective measurement of daytime alertness in patients with obstructive sleep apnea. Further studies are needed to clarify the association between simulated-driving performance and on-road crash risk of patients with sleep disordered breathing. Citation: Pizza F; Contardi S; Mondini S; Trentin L; Cirignotta F. Daytime sleepiness and driving performance in patients with obstructive sleep apnea: comparison of the MSLT, the MWT, and a simulated driving task. SLEEP 2009;32(3):382-391. PMID:19294958

  18. Driving violations observed: an Australian study.

    PubMed

    Glendon, A Ian

    2007-08-01

    This study analyses 2,765 cases of driving behaviours in three Australian states - New South Wales, Queensland and Victoria. Data were gathered from in-car coordinated video and audio recording sequences in free-flowing traffic along two-, three- and four-lane highways with varying speed limits on all days of the week in daylight and fine weather conditions. Explanatory variables included driver age group and gender, passenger characteristics and vehicle age and type. Response variables included driving violations and other driving behaviours, including lane use, speeding, close following (tailgating), driver's hands position and mobile phone use. Data were analysed qualitatively and quantitatively. By focusing upon vehicle and driver characteristics, and their impact on driving behaviours, including identified violations, this study explores some implications both for future research and for traffic policy makers.

  19. Rifaximin Improves Driving Simulator Performance in a Randomized Trial of Patients with Minimal Hepatic Encephalopathy

    PubMed Central

    Bajaj, Jasmohan S; Heuman, Douglas M; Wade, James B; Gibson, Douglas P; Saeian, Kia; Wegelin, Jacob A; Hafeezullah, Muhammad; Bell, Debulon E; Sterling, Richard K; Stravitz, R. Todd; Fuchs, Michael; Luketic, Velimir; Sanyal, Arun J

    2010-01-01

    Background & Aims Patients with cirrhosis and minimal hepatic encephalopathy (MHE) have driving difficulties but the effects of therapy on driving performance have not been assessed. We evaluated whether performance on a driving simulator improves in patients with MHE following treatment with rifaximin. Methods Patients with MHE who were current drivers were randomly assigned to placebo or rifaximin groups and followed for 8 weeks (n=42). Patients underwent driving simulation (driving and navigation tasks) at the start (baseline) and end of the study. We evaluated patients’ cognitive abilities, quality-of-life (using the Sickness Impact Profile [SIP]), serum levels of ammonia, levels of inflammatory cytokines, and MELD scores. The primary outcome was percent who improved in driving performance, calculated by: total driving errors=speeding + illegal turns + collisions. Results Over the 8-week study period, patients given rifaximin made significantly greater improvements than those given placebo in avoiding total driving errors (76% vs. 31%, P=0.013), speeding (81% vs. 33%, P=0.005), and illegal turns (62% vs. 19%, P=0.01). Of patients given rifaximin, 91% improved their cognitive performance, compared with 61% of patients given placebo (P=0.01); they also made improvements in the psycho-social dimension of the SIP, compared with the placebo group (P=0.04). Adherence to the assigned drug averaged 92%. Neither group had changes in ammonia levels or MELD scores, but patients in the rifaximin group had increased levels of the anti-inflammatory cytokine interleukin-10. Conclusions Patients with MHE significantly improve driving simulator performance following treatment with rifaximin, compared with placebo. PMID:20849805

  20. Acute Effects of Alcohol on Inhibitory Control and Simulated Driving in DUI Offenders

    PubMed Central

    Van Dyke, Nicholas; Fillmore, Mark T.

    2014-01-01

    Introduction The public health costs associated with alcohol-related traffic accidents have prompted considerable research aimed at identifying characteristics of individuals who drive under the influence (DUI) in order to improve treatment and prevention strategies. Survey studies consistently show that DUI offenders self-report higher levels of impulsivity compared to their nonoffending counterparts. However, little is known about how individuals with a DUI history respond under alcohol. Inhibitory control is a behavioral component of impulsivity thought to underlie risky drinking and driving behaviors. Method The present study examined the degree to which DUI drivers display deficits of inhibitory control in response to alcohol and the degree to which alcohol impaired their simulated driving performance. It was hypothesized that DUI offenders would display an increased sensitivity to the acute impairing effects of alcohol on simulated driving performance. Young adult drivers with a history of DUI and a demographically-comparable group of drivers with no history of DUI (controls) were tested following a 0.65 g/kg dose of alcohol and a placebo. Inhibitory control was measured using a cued go/no-go task. Drivers then completed a driving simulation task that yielded multiple indicators of driving performance, such as within-lane deviation, steering rate, centerline crossings and road edge excursions, and drive speed. Results Results showed that although DUI offenders self-reported greater levels of impulsivity than did controls, no group differences were observed in the degree to which alcohol impaired inhibitory control and driving performance. The findings point to the need to identify other aspects of behavioral dysfunction underlying the self-reported impulsivity among DUI offenders, and to better understand the specific driving situations that might pose greater risk to DUI offenders. PMID:24913486

  1. Peer Passenger Norms and Pressure: Experimental Effects on Simulated Driving Among Teenage Males.

    PubMed

    Bingham, C Raymond; Simons-Morton, Bruce G; Pradhan, Anuj K; Li, Kaigang; Almani, Farideh; Falk, Emily B; Shope, Jean T; Buckley, Lisa; Ouimet, Marie Claude; Albert, Paul S

    2016-08-01

    Serious crashes are more likely when teenage drivers have teenage passengers. One likely source of this increased risk is social influences on driving performance. This driving simulator study experimentally tested the effects of peer influence (i.e., risk-accepting compared to risk-averse peer norms reinforced by pressure) on the driving risk behavior (i.e., risky driving behavior and inattention to hazards) of male teenagers. It was hypothesized that peer presence would result in greater driving risk behavior (i.e., increased driving risk and reduced latent hazard anticipation), and that the effect would be greater when the peer was risk-accepting. Fifty-three 16- and 17-year-old male participants holding a provisional U.S., State of Michigan driver license were randomized to either a risk-accepting or risk-averse condition. Each participant operated a driving simulator while alone and separately with a confederate peer passenger. The simulator world included scenarios designed to elicit variation in driving risk behavior with a teen passenger present in the vehicle. Significant interactions of passenger presence (passenger present vs. alone) by risk condition (risk-accepting vs. risk-averse) were observed for variables measuring: failure to stop at yellow light intersections (Incident Rate Ratio (IRR)=2.16; 95% Confidence Interval [95CI]=1.06, 4.43); higher probability of overtaking (IRR=10.17; 95CI=1.43, 73.35); shorter left turn latency (IRR=0.43; 95CI=0.31,0.60); and, failure to stop at an intersection with an occluded stop sign (IRR=7.90; 95CI=2.06,30.35). In all cases, greater risky driving by participants was more likely with a risk-accepting passenger versus a risk-averse passenger present and a risk-accepting passenger present versus driving alone. Exposure of male teenagers to a risk-accepting confederate peer passenger who applied peer influence increased simulated risky driving behavior compared with exposure to a risk-averse confederate peer

  2. Peer Passenger Norms and Pressure: Experimental Effects on Simulated Driving Among Teenage Males

    PubMed Central

    Bingham, C. Raymond; Simons-Morton, Bruce G.; Pradhan, Anuj K.; Li, Kaigang; Almani, Farideh; Falk, Emily B.; Shope, Jean T.; Buckley, Lisa; Ouimet, Marie Claude; Albert, Paul S.

    2016-01-01

    Objective Serious crashes are more likely when teenage drivers have teenage passengers. One likely source of this increased risk is social influences on driving performance. This driving simulator study experimentally tested the effects of peer influence (i.e., risk-accepting compared to risk-averse peer norms reinforced by pressure) on the driving risk behavior (i.e., risky driving behavior and inattention to hazards) of male teenagers. It was hypothesized that peer presence would result in greater driving risk behavior (i.e., increased driving risk and reduced latent hazard anticipation), and that the effect would be greater when the peer was risk-accepting. Methods Fifty-three 16- and 17-year-old male participants holding a provisional U.S., State of Michigan driver license were randomized to either a risk-accepting or risk-averse condition. Each participant operated a driving simulator while alone and separately with a confederate peer passenger. The simulator world included scenarios designed to elicit variation in driving risk behavior with a teen passenger present in the vehicle. Results Significant interactions of passenger presence (passenger present vs. alone) by risk condition (risk-accepting vs. risk-averse) were observed for variables measuring: failure to stop at yellow light intersections (Incident Rate Ratio (IRR)=2.16; 95% Confidence Interval [95CI]=1.06, 4.43); higher probability of overtaking (IRR=10.17; 95CI=1.43, 73.35); shorter left turn latency (IRR=0.43; 95CI=0.31,0.60); and, failure to stop at an intersection with an occluded stop sign (IRR=7.90; 95CI=2.06,30.35). In all cases, greater risky driving by participants was more likely with a risk-accepting passenger versus a risk-averse passenger present and a risk-accepting passenger present versus driving alone. Conclusions Exposure of male teenagers to a risk-accepting confederate peer passenger who applied peer influence increased simulated risky driving behavior compared with exposure to a

  3. Correlation between Driver Subjective Fatigue and Bus Lateral Position in a Driving Simulator

    PubMed Central

    Gharagozlou, Faramarz; Mazloumi, Adel; Saraji, Gebraeil Nasl; Nahvi, Ali; Ashouri, Mohammadreza; Mozaffari, Hamed

    2015-01-01

    Background: Driver fatigue as a leading cause of death in the transportation industry can impair the driving performance in long-distance driving task. Studies on the links of driver subjective fatigue and the bus lateral position are still an exploratory issue that requires further investigation. This study aimed to determine the correlation between the driver subjective fatigue and the bus lateral position in a driving simulator. Methods: This descriptive-analytical research was conducted on 30 professional male bus drivers participated in a two-hour driving session. The driver subjective fatigue was assessed by the Fatigue Visual Analogue Scale (F-VAS) at 10-min intervals. Simultaneously, the performance measures of lane drifting as the mean and standard deviation of the bus lateral position (SDLP) were calculated during the simulated driving task. Descriptive statistics and the Spearman correlation coefficient were used to describe and analyze the data. Results: Fatigue levels had an increasing trend as the time-on-task of driving increased. Time-on-task of driving had the greatest effect on the fatigue self-evaluation (r = 0.605, p < 0.0001). The results showed a significant correlation between fatigue self-evaluation and bus lateral position (r = 0.567, p < 0.0001). Conclusion: As the time of driving increased, driving performance was affected adversely, as shown by the increase in the SDLP. Even so, the effect of individual differences on driving performance should not be overlooked. This work concludes that predicting the state of a driver fatigue based on the group mean data has some complications for any application. PMID:26396734

  4. Correlation between Driver Subjective Fatigue and Bus Lateral Position in a Driving Simulator.

    PubMed

    Gharagozlou, Faramarz; Mazloumi, Adel; Saraji, Gebraeil Nasl; Nahvi, Ali; Ashouri, Mohammadreza; Mozaffari, Hamed

    2015-08-01

    Driver fatigue as a leading cause of death in the transportation industry can impair the driving performance in long-distance driving task. Studies on the links of driver subjective fatigue and the bus lateral position are still an exploratory issue that requires further investigation. This study aimed to determine the correlation between the driver subjective fatigue and the bus lateral position in a driving simulator. This descriptive-analytical research was conducted on 30 professional male bus drivers participated in a two-hour driving session. The driver subjective fatigue was assessed by the Fatigue Visual Analogue Scale (F-VAS) at 10-min intervals. Simultaneously, the performance measures of lane drifting as the mean and standard deviation of the bus lateral position (SDLP) were calculated during the simulated driving task. Descriptive statistics and the Spearman correlation coefficient were used to describe and analyze the data. Fatigue levels had an increasing trend as the time-on-task of driving increased. Time-on-task of driving had the greatest effect on the fatigue self-evaluation (r = 0.605, p < 0.0001). The results showed a significant correlation between fatigue self-evaluation and bus lateral position (r = 0.567, p < 0.0001). As the time of driving increased, driving performance was affected adversely, as shown by the increase in the SDLP. Even so, the effect of individual differences on driving performance should not be overlooked. This work concludes that predicting the state of a driver fatigue based on the group mean data has some complications for any application.

  5. Training driving ability in a traumatic brain-injured individual using a driving simulator: a case report

    PubMed Central

    Imhoff, Sarah; Lavallière, Martin; Germain-Robitaille, Mathieu; Teasdale, Normand; Fait, Philippe

    2017-01-01

    Background Traumatic brain injury (TBI) causes functional deficits that may significantly interfere with numerous activities of daily living such as driving. We report the case of a 20-year-old woman having lost her driver’s license after sustaining a moderate TBI. Objective We aimed to evaluate the effectiveness of an in-simulator training program with automated feedback on driving performance in a TBI individual. Methods The participant underwent an initial and a final in-simulator driving assessment and 11 in-simulator training sessions with driving-specific automated feedbacks. Driving performance (simulation duration, speed regulation and lateral positioning) was measured in the driving simulator. Results Speeding duration decreased during training sessions from 1.50 ± 0.80 min (4.16 ± 2.22%) to 0.45 ± 0.15 min (0.44 ± 0.42%) but returned to initial duration after removal of feedbacks for the final assessment. Proper lateral positioning improved with training and was maintained at the final assessment. Time spent in an incorrect lateral position decreased from 18.85 min (53.61%) in the initial assessment to 1.51 min (4.64%) on the final assessment. Conclusion Driving simulators represent an interesting therapeutic avenue. Considerable research efforts are needed to confirm the effectiveness of this method for driving rehabilitation of individuals who have sustained a TBI. PMID:28243152

  6. Self-report measures of distractibility as correlates of simulated driving performance.

    PubMed

    Kass, Steven J; Beede, Kristen E; Vodanovich, Stephen J

    2010-05-01

    The present study investigated the relationship between self-reported measures pertaining to attention difficulties and simulated driving performance while distracted. Thirty-six licensed drivers participated in a simulator driving task while engaged in a cell phone conversation. The participants completed questionnaires assessing their tendency toward boredom, cognitive failures, and behaviors associated with attention deficit and hyperactivity. Scores on these measures were significantly correlated with various driving outcomes (e.g., speed, lane maintenance, reaction time). Significant relationships were also found between one aspect of boredom proneness (i.e., inability to generate interest or concentrate) and self-reports of past driving behavior (moving violations). The current study may aid in the understanding of how individual differences in driver distractibility may contribute to unsafe driving behaviors and accident involvement. Additionally, such measures may assist in the identification of individuals at risk for committing driving errors due to being easily distracted. The benefits and limitations of conducting and interpreting simulation research are discussed. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  7. Phasic dopamine as a prediction error of intrinsic and extrinsic reinforcements driving both action acquisition and reward maximization: a simulated robotic study.

    PubMed

    Mirolli, Marco; Santucci, Vieri G; Baldassarre, Gianluca

    2013-03-01

    An important issue of recent neuroscientific research is to understand the functional role of the phasic release of dopamine in the striatum, and in particular its relation to reinforcement learning. The literature is split between two alternative hypotheses: one considers phasic dopamine as a reward prediction error similar to the computational TD-error, whose function is to guide an animal to maximize future rewards; the other holds that phasic dopamine is a sensory prediction error signal that lets the animal discover and acquire novel actions. In this paper we propose an original hypothesis that integrates these two contrasting positions: according to our view phasic dopamine represents a TD-like reinforcement prediction error learning signal determined by both unexpected changes in the environment (temporary, intrinsic reinforcements) and biological rewards (permanent, extrinsic reinforcements). Accordingly, dopamine plays the functional role of driving both the discovery and acquisition of novel actions and the maximization of future rewards. To validate our hypothesis we perform a series of experiments with a simulated robotic system that has to learn different skills in order to get rewards. We compare different versions of the system in which we vary the composition of the learning signal. The results show that only the system reinforced by both extrinsic and intrinsic reinforcements is able to reach high performance in sufficiently complex conditions.

  8. Quantitative sleep EEG and polysomnographic predictors of driving simulator performance in obstructive sleep apnea.

    PubMed

    Vakulin, Andrew; D'Rozario, Angela; Kim, Jong-Won; Watson, Brooke; Cross, Nathan; Wang, David; Coeytaux, Alessandra; Bartlett, Delwyn; Wong, Keith; Grunstein, Ronald

    2016-02-01

    To improve identification of obstructive sleep apnea (OSA) patients at risk of driving impairment, this study explored predictors of driving performance impairment in untreated OSA patients using clinical PSG metrics, sleepiness questionnaires and quantitative EEG markers from routine sleep studies. Seventy-six OSA patients completed sleepiness questionnaires and driving simulator tests in the evening of their diagnostic sleep study. All sleep EEGs were subjected to quantitative power spectral analysis. Correlation and multivariate linear regression were used to identify the strongest predictors of driving simulator performance. Absolute EEG spectral power across all frequencies (0.5-32 Hz) throughout the entire sleep period and separately in REM and NREM sleep, (r range 0.239-0.473, all p<0.05), as well as sleep onset latency (r=0.273, p<0.017) positively correlated with driving simulator steering deviation. Regression models revealed that amongst clinical and qEEG variables, the significant predictors of worse steering deviation were greater total EEG power during NREM and REM sleep, greater beta EEG power in NREM and greater delta EEG power in REM (range of variance explained 5-17%, t range 2.29-4.0, all p<0.05) and sleep onset latency (range of variance explained 4-9%, t range 2.15-2.5, all p<0.05). In OSA patients, increased EEG power, especially in the faster frequency (beta) range during NREM sleep and slower frequency (delta) range in REM sleep were associated with worse driving performance, while no relationships were observed with clinical metrics e.g. apnea, arousal or oxygen indices. Quantitative EEG analysis in OSA may provide useful markers of driving impairment risk. Future studies are necessary to confirm these findings and assess the clinical significance of quantitative EEG as predictors of driving impairment in OSA. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  9. Relationship between obstructive sleep apnoea, driving simulator performance, and risk of road traffic accidents

    PubMed Central

    Turkington, P; Sircar, M; Allgar, V; Elliott, M

    2001-01-01

    BACKGROUND—Obstructive sleep apnoea (OSA) has been shown to be associated with an increased risk of road traffic accidents (RTAs). Predicting the driving ability and risk of RTAs in an individual with OSA is difficult. On-road testing is the gold standard, but this is time consuming, expensive, and potentially dangerous. Simple computer based driving simulators have been developed to help determine driving ability. Although patients with OSA have been shown to perform poorly compared with matched controls, it is not known whether these simulators can predict those at most risk of accidents. In this study we evaluated whether data derived from a simple driving simulator provided information over and above that obtained from the history and a sleep study that might be useful for advising patients about driving.
METHODS—We examined 150 patients admitted for routine sleep studies for investigation of OSA and snoring. Each patient performed a 20 minute driving simulation and completed a questionnaire regarding their driving history and experience.
RESULTS—Logistic regression analysis was used to investigate factors associated with patients' performance on the simulator. It was found that patient characteristics, older age (OR 1.05, 95% CI 1.01 to 1.09, p<0.01), female sex (OR 9.32, 95% CI 1.09 to 79.4,p<0.04), and self-reported alcohol consumption (OR 1.04, 95% CI 1.01 to 1.07, p<0.01) had the greatest influence; however, the number of self-reported near miss accidents was independently associated with a poor performance (OR 2.62, 95% CI 1.00 to 6.88,p<0.05). A further logistic regression was used to investigate whether clinical history, sleep study results, and data from the driving simulator were useful in classifying patients with OSA as having had an RTA. The number of off-road events per hour on the simulator was independently associated with a history of previous RTA (OR 1.004, 95% CI 1.0004 to 1.008, p<0.03). The Epworth score was independently

  10. Cognitive Functioning and Driving Simulator Performance in Middle-aged and Older Adults with HIV

    PubMed Central

    Vance, David E.; Fazeli, Pariya L.; Ball, David A.; Slater, Larry Z.; Ross, Lesley A.

    2014-01-01

    Nearly half of people living with HIV experience cognitive deficits that may impact instrumental activities of daily living. As the number of people aging with HIV increases, concerns mount that disease-related cognitive deficits may be compounded by age-related deficits, which may further compromise everyday functions such as driving. In this cross-sectional pilot study, during a 2.5-hour visit, 26 middle-aged and older adults (40+ years) were administered demographic, health, psychosocial, and driving habits questionnaires; cognitive assessments; and driving simulator tests. Although CD4+T lymphocyte count and viral load were unrelated to driving performance, older age was related to poorer driving. Furthermore, poorer visual speed of processing performance (i.e., Useful Field of View) was related to poorer driving performance (e.g., average gross reaction time). Mixed findings were observed between driving performance and cognitive function on self-reported driving habits of participants. Implications for these findings on nursing practice and research are posited. PMID:24513104

  11. Simulated driving performance under alcohol: effects on driver-risk versus driver-skill

    PubMed Central

    Laude, Jennifer R.; Fillmore, Mark T.

    2015-01-01

    Background Those who place their vehicles closer to others on the roadway are said to have high risk acceptance, and this contributes to motor vehicle crashes. However, the effect of alcohol on this risky driving behavior is understudied. Behavioral mechanisms that contribute to risky driving are also not well understood. Further, whether increased risk-taking behavior in a driver co-occurs with pronounced impairment in the driver’s skill is unknown. Methods The study examined the effect of alcohol on risk and skill-relevant driving and whether riskier drivers were also those who showed high skill impairment. The relationship between driving behavior and inhibitory control was also tested. Participants completed two driving simulations. In the first drive test, risky driving was encouraged and in the second test, skill-relevant driving was emphasized. The cued go/no-go task provided a measure inhibitory control. Tests were completed under a 0.65 g/kg alcohol and 0.0 g/kg (placebo) dose of alcohol. Results Alcohol impaired a measure of driving skill and increased driver risk taking. It was also found that riskier drivers were not necessarily those who showed the greatest impairments in skill. Poorer inhibitory control was associated with greater driver risk in the sober state. Conclusions Alcohol-induced risk-taking behaviors can be dissociable from impairing effects on driver skill and poor inhibitory control is selectively related to risky driving. As such, a distinction between skill and risk-related driving needs to be made in the investigation of problems concerning DUI-related accidents and fatalities in future research. PMID:26231663

  12. Methodical aspects of text testing in a driving simulator.

    PubMed

    Sundin, A; Patten, C J D; Bergmark, M; Hedberg, A; Iraeus, I-M; Pettersson, I

    2012-01-01

    A test with 30 test persons was conducted in a driving simulator. The test was a concept exploration and comparison of existing user interaction technologies for text message handling with focus on traffic safety and experience (technology familiarity and learning effects). Focus was put on methodical aspects how to measure and how to analyze the data. Results show difficulties with the eye tracking system (calibration etc.) per se, and also include the subsequent raw data preparation. The physical setup in the car where found important for the test completion.

  13. Cognitive, on-road, and simulator-based driving assessment after stroke.

    PubMed

    Hird, Megan A; Vetivelu, Abeiramey; Saposnik, Gustavo; Schweizer, Tom A

    2014-01-01

    Driving is a complex activity that requires intact cognitive, behavioral, and motor function. Stroke is one of the most prevalent neurologic impairments and can affect all of these functions. However, diagnosis of stroke is not a definitive indicator of driving impairment. Determining fitness to drive after stroke is a very complex process and is typically based on cognitive assessments, on-road performance, simulator-based assessment, or a combination of the three. The aim of this review was to provide (1) a systematic review of the literature on cognitive, on-road, and simulator assessment after stroke, and (2) address the existing limitations and inconsistencies in stroke and driving research. Our results indicated that of 1413 total stroke patients, 748 definitively passed and 367 definitely failed an on-road assessment, with minimal information provided about clinical presentation. In addition, although the Stroke Driver Screening Assessment, the Useful Field of View Test, and the Rey-O Complex Figure test may have some utility in predicting driving performance, most cognitive measures have been inconsistently and minimally explored. Several limitations were observed across studies such as procedural inconsistencies, including outcome variables used (eg, driving cessation and pass/fail classification) and the heterogeneity of patient samples (eg, time since stroke and stroke location). Due, in part, to the larger variability in results of cognitive, on-road, and simulator-based assessment, there is no consensus regarding a valid and reliable driving assessment for physicians. Future studies should assess poststroke driving fitness by differentiating different stages, severities, and locations of stroke.

  14. Safety evaluation model of urban cross-river tunnel based on driving simulation.

    PubMed

    Ma, Yingqi; Lu, Linjun; Lu, Jian John

    2017-09-01

    Currently, Shanghai urban cross-river tunnels have three principal characteristics: increased traffic, a high accident rate and rapidly developing construction. Because of their complex geographic and hydrological characteristics, the alignment conditions in urban cross-river tunnels are more complicated than in highway tunnels, so a safety evaluation of urban cross-river tunnels is necessary to suggest follow-up construction and changes in operational management. A driving risk index (DRI) for urban cross-river tunnels was proposed in this study. An index system was also constructed, combining eight factors derived from the output of a driving simulator regarding three aspects of risk due to following, lateral accidents and driver workload. Analytic hierarchy process methods and expert marking and normalization processing were applied to construct a mathematical model for the DRI. The driving simulator was used to simulate 12 Shanghai urban cross-river tunnels and a relationship was obtained between the DRI for the tunnels and the corresponding accident rate (AR) via a regression analysis. The regression analysis results showed that the relationship between the DRI and the AR mapped to an exponential function with a high degree of fit. In the absence of detailed accident data, a safety evaluation model based on factors derived from a driving simulation can effectively assess the driving risk in urban cross-river tunnels constructed or in design.

  15. Behavioral and Cardiovascular Responses to Frustration During Simulated Driving Tasks in Young Adults With and Without Attention Disorder Symptoms

    PubMed Central

    Oliver, Michele L.; Nigg, Joel T.; Cassavaugh, Nicholas D.; Backs, Richard W.

    2015-01-01

    Objective The present study examined the role of negative emotions on driving performance in relation to ADHD, by comparing young adults scoring high on measures of ADHD (n = 20) with a control group (n = 22). Method The authors used cardiorespiratory physiological measures, simulated driving behavior, and self-report to examine how participants with high and low ADHD symptoms responded to frustration and to determine how frustration affected simulated driving performance. Results Groups did not differ in operational driving skills, but participants with high ADHD symptoms reported more frustration and exhibited more impairment at the tactical level of driving performance than the controls. There was significant suppression of respiratory sinus arrhythmia from resting baseline during tasks, but it did not differ between groups during driving. Conclusion This article proposes that remedial driver training for ADHD populations should focus more on the control of negative emotions rather than on attention or fundamental driving skills. PMID:21490175

  16. Detecting and Quantifying Mind Wandering during Simulated Driving

    PubMed Central

    Baldwin, Carryl L.; Roberts, Daniel M.; Barragan, Daniela; Lee, John D.; Lerner, Neil; Higgins, James S.

    2017-01-01

    Mind wandering is a pervasive threat to transportation safety, potentially accounting for a substantial number of crashes and fatalities. In the current study, mind wandering was induced through completion of the same task for 5 days, consisting of a 20-min monotonous freeway-driving scenario, a cognitive depletion task, and a repetition of the 20-min driving scenario driven in the reverse direction. Participants were periodically probed with auditory tones to self-report whether they were mind wandering or focused on the driving task. Self-reported mind wandering frequency was high, and did not statistically change over days of participation. For measures of driving performance, participant labeled periods of mind wandering were associated with reduced speed and reduced lane variability, in comparison to periods of on task performance. For measures of electrophysiology, periods of mind wandering were associated with increased power in the alpha band of the electroencephalogram (EEG), as well as a reduction in the magnitude of the P3a component of the event related potential (ERP) in response to the auditory probe. Results support that mind wandering has an impact on driving performance and the associated change in driver’s attentional state is detectable in underlying brain physiology. Further, results suggest that detecting the internal cognitive state of humans is possible in a continuous task such as automobile driving. Identifying periods of likely mind wandering could serve as a useful research tool for assessment of driver attention, and could potentially lead to future in-vehicle safety countermeasures. PMID:28848414

  17. A comparison of the effect of mobile phone use and alcohol consumption on driving simulation performance.

    PubMed

    Leung, Sumie; Croft, Rodney J; Jackson, Melinda L; Howard, Mark E; McKenzie, Raymond J

    2012-01-01

    The present study compared the effects of a variety of mobile phone usage conditions to different levels of alcohol intoxication on simulated driving performance and psychomotor vigilance. Twelve healthy volunteers participated in a crossover design in which each participant completed a simulated driving task on 2 days, separated by a 1-week washout period. On the mobile phone day, participants performed the simulated driving task under each of 4 conditions: no phone usage, a hands-free naturalistic conversation, a hands-free cognitively demanding conversation, and texting. On the alcohol day, participants performed the simulated driving task at four different blood alcohol concentration (BAC) levels: 0.00, 0.04, 0.07, and 0.10. Driving performance was assessed by variables including time within target speed range, time spent speeding, braking reaction time, speed deviation, and lateral lane position deviation. In the BAC 0.07 and 0.10 alcohol conditions, participants spent less time in the target speed range and more time speeding and took longer to brake in the BAC 0.04, 0.07, and 0.10 than in the BAC 0.00 condition. In the mobile phone condition, participants took longer to brake in the natural hands-free conversation, cognitively demanding hands-free conversation and texting conditions and spent less time in the target speed range and more time speeding in the cognitively demanding, hands-free conversation, and texting conditions. When comparing the 2 conditions, the naturalistic conversation was comparable to the legally permissible BAC level (0.04), and the cognitively demanding and texting conversations were similar to the BAC 0.07 to 0.10 results. The findings of the current laboratory study suggest that very simple conversations on a mobile phone may not represent a significant driving risk (compared to legally permissible BAC levels), whereas cognitively demanding, hands-free conversation, and particularly texting represent significant risks to driving.

  18. Wakefulness in young and elderly subjects driving at night in a car simulator.

    PubMed

    Lowden, Arne; Anund, Anna; Kecklund, Göran; Peters, Björn; Akerstedt, Torbjörn

    2009-09-01

    Young drivers are over-represented in nighttime traffic accidents and several studies have suggested that many accidents are associated with elevated sleepiness levels. It has been suggested that there may be a connection between lowered wake capacity and functional sensory motor skills on the one hand and sleep deprivation at the circadian low in young drivers on the other. Performance during a 45/min evening and night drive among young (n=10, age range 18-24 years) and elderly (n=10, age range 55-64 years) subjects was studied using a moving base driving simulator. EEG was measured continuously. Every 5 min, subjects were rated on the Karolinska Sleepiness Scale (KSS). Saliva cortisol was assessed before and after each drive. The results showed that sleepiness increased across each drive and was higher among young drivers at night. Relative EEG power increased among older drivers for frequencies of 10-16Hz. The sigma 1 frequency band (12-14Hz) proved particularly sensitive to sustained driving, and was elevated among subjects in the elderly group. Cortisol levels before and after the evening and night drive showed higher mean levels for elderly subjects. The present study has demonstrated that young drivers were more sleepy while driving at night. The effects could represent a mobilization of effort and a reorganization of brain firing pattern among older subjects, possibly reflecting better ability and effort to resist sleepiness.

  19. The effects of anabolic steroids on driving performance as assessed by the Iowa Driver Simulator.

    PubMed

    Ellingrod, V L; Perry, P J; Yates, W R; MacIndoe, J H; Watson, G; Arndt, S; Holman, T L

    1997-11-01

    The effect of physiologic (100 mg/wk) and supraphysiologic (250 and 500 mg/wk) doses of testosterone cypionate (TC) on automobile driving were studied using the Iowa Driver Simulator. Six normal subject volunteers were studied off TC and on TC once steady-state concentrations were achieved after at least three weeks of dosing. Despite the administration of supraphysiologic testosterone doses, an increase in aggressive driving behavior was not detected. Likewise, corresponding psychometric testing using the Buss-Durkee Hostility Inventory to assess aggression was unable to detect any change in aggression in the test subjects. Although aggressive driving behavior may be increased by testosterone administration, the drug itself may not be responsible for these effects. Supraphysiologic doses greater than 500 mg/wk and a semi-controlled research environment may be necessary to produce this effect since case reports of AAS abuse causing altered driving behavior may be multifactorial in nature.

  20. Peer passenger influences on male adolescent drivers’ visual scanning behavior during simulated driving

    PubMed Central

    Pradhan, Anuj K.; Li, Kaigang; Bingham, C. Raymond; Simons-Morton, Bruce; Ouimet, Marie Claude; Shope, Jean T.

    2014-01-01

    Purpose There is a higher likelihood of crashes and fatalities when an adolescent drives with peer passengers, especially for male drivers and male passengers. Simulated driving of male adolescent drivers with male peer passengers was studied to examine passenger influences on distraction and inattention. Methods Male adolescents drove in a high-fidelity driving simulator with a male confederate who posed either as a risk-accepting or risk-averse passenger. Drivers’ eye-movements were recorded. The visual scanning behavior of the drivers was compared when driving alone versus when driving with a passenger, and when driving with a risk-accepting versus a risk-averse passenger. Results The visual scanning of a driver significantly narrowed horizontally and vertically when driving with a peer passenger. There were no significant differences in the times the drivers’ eyes were off the forward roadway when driving with a passenger versus when driving alone. Some significant correlations were found between personality characteristics and the outcome measures. Conclusions The presence of a male peer passenger was associated with a reduction in the visual scanning range of male adolescent drivers. This reduction could be a result of potential cognitive load imposed on the driver due to the presence of a passenger and the real or perceived normative influences or expectations from the passenger. Implications and contribution The presence of male peer passengers was associated with deficient visual scanning in male adolescent drivers. Such reduced scanning behavior is evident in drivers with high cognitive load. Further investigation of passenger influences on adolescent drivers should include examination of distraction and inattention aspects of passenger influence. PMID:24759440

  1. Physical Processes for Driving Ionospheric Outflows in Global Simulations

    NASA Technical Reports Server (NTRS)

    Moore, Thomas Earle; Strangeway, Robert J.

    2009-01-01

    We review and assess the importance of processes thought to drive ionospheric outflows, linking them as appropriate to the solar wind and interplanetary magnetic field, and to the spatial and temporal distribution of their magnetospheric internal responses. These begin with the diffuse effects of photoionization and thermal equilibrium of the ionospheric topside, enhancing Jeans' escape, with ambipolar diffusion and acceleration. Auroral outflows begin with dayside reconnexion and resultant field-aligned currents and driven convection. These produce plasmaspheric plumes, collisional heating and wave-particle interactions, centrifugal acceleration, and auroral acceleration by parallel electric fields, including enhanced ambipolar fields from electron heating by precipitating particles. Observations and simulations show that solar wind energy dissipation into the atmosphere is concentrated by the geomagnetic field into auroral regions with an amplification factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Internal plasmas thus enable electromagnetic driving via coupling to the plasma, neutral gas and by extension, the entire body " We assess the Importance of each of these processes in terms of local escape flux production as well as global outflow, and suggest methods for their implementation within multispecies global simulation codes. We complete 'he survey with an assessment of outstanding obstacles to this objective.

  2. Unobtrusive vehicle motion prediction cues reduced simulator sickness during passive travel in a driving simulator.

    PubMed

    Jeng-Weei Lin, James; Parker, D E; Lahav, Michal; Furness, T A

    2005-05-15

    This study investigated cues that permit prediction of turns during passive movement through a virtual environment. Effects on simulator sickness (SS), presence and enjoyment were examined. Subjects were exposed to complex visual motion through a cartoon-like simulated environment in a driving simulator. Forward velocity remained constant and the motion path was the same across all experimental conditions. Using a within-subject design, we examined visual paths that provided different levels of cue salience - detailed, simplified and no cues - for the upcoming simulated vehicle motion. Following each trial, participants completed questionnaires on SS, presence and enjoyment. After all of the trials were completed, a debriefing determined participants' perceptions of vehicle motion attributes and their awareness of the prediction cues. The results showed that SS in the no-cue condition was significantly greater than that in the conditions that provided vehicle motion cues. Presence and enjoyment responses were not different across the conditions. No participants reported differences between prediction cue conditions or recognized that the vehicle motion followed the same path across trials. However, participants tended to report that the motion was smoother for the detailed-cue than the no-cue condition. Participants ranked turn predictability as higher in conditions with prediction cues. The results support the hypothesis that unobtrusive and unreported motion cues may alleviate SS in a virtual environment.

  3. Effects of vibration on occupant driving performance under simulated driving conditions.

    PubMed

    Azizan, Amzar; Fard, M; Azari, Michael F; Jazar, Reza

    2017-04-01

    Although much research has been devoted to the characterization of the effects of whole-body vibration on seated occupants' comfort, drowsiness induced by vibration has received less attention to date. There are also little validated measurement methods available to quantify whole body vibration-induced drowsiness. Here, the effects of vibration on drowsiness were investigated. Twenty male volunteers were recruited for this experiment. Drowsiness was measured in a driving simulator, before and after 30-min exposure to vibration. Gaussian random vibration, with 1-15 Hz frequency bandwidth was used for excitation. During the driving session, volunteers were required to obey the speed limit of 100 kph and maintain a steady position on the left-hand lane. A deviation in lane position, steering angle variability, and speed deviation were recorded and analysed. Alternatively, volunteers rated their subjective drowsiness by Karolinska Sleepiness Scale (KSS) scores every 5-min. Following 30-min of exposure to vibration, a significant increase of lane deviation, steering angle variability, and KSS scores were observed in all volunteers suggesting the adverse effects of vibration on human alertness level.

  4. Acute effects of alcohol on inhibitory control and simulated driving in DUI offenders.

    PubMed

    Van Dyke, Nicholas; Fillmore, Mark T

    2014-06-01

    The public health costs associated with alcohol-related traffic accidents have prompted considerable research aimed at identifying characteristics of individuals who drive under the influence (DUI) in order to improve treatment and prevention strategies. Survey studies consistently show that DUI offenders self-report higher levels of impulsivity compared to their nonoffending counterparts. However, little is known about how individuals with a DUI history respond under alcohol. Inhibitory control is a behavioral component of impulsivity thought to underlie risky drinking and driving behaviors. The present study examined the degree to which DUI drivers display deficits of inhibitory control in response to alcohol and the degree to which alcohol impaired their simulated driving performance. It was hypothesized that DUI offenders would display an increased sensitivity to the acute impairing effects of alcohol on simulated driving performance. Young adult drivers with a history of DUI and a demographically-comparable group of drivers with no history of DUI (controls) were tested following a 0.65 g/kg dose of alcohol and a placebo. Inhibitory control was measured by using a cued go/no-go task. Drivers then completed a driving simulation task that yielded multiple indicators of driving performance, such as within-lane deviation, steering rate, centerline crossings and road edge excursions, and drive speed. Results showed that although DUI offenders self-reported greater levels of impulsivity than did controls, no group differences were observed in the degree to which alcohol impaired inhibitory control and driving performance. The findings point to the need to identify other aspects of behavioral dysfunction underlying the self-reported impulsivity among DUI offenders, and to better understand the specific driving situations that might pose greater risk to DUI offenders. The systematic study of candidate cognitive deficits in DUI offenders will provide important

  5. [Effect of air-electric fields on driving and reaction patterns. Test subjects in the car driving simulator (author's transl)].

    PubMed

    Anselm, D; Danner, M; Kirmaier, N; König, H L; Müller-Limmroth, W; Reis, A; Schauerte, W

    1977-06-10

    In the relevant frequency range of about 10 Hertz cars can be considered very largely as Faraday cages and consequently as screens against air-electric fields. This may have a negative influence on driving and reaction patterns as a result. In an extensive investigation 48 subjects in a driving simulator were exposed to definite artificially produced air-electric fields. The self-rating of the performance and concentration of the subjects, reaction times and driving errors were determined. While the reaction times remained practically constant, the driving behavior of the subjects improved.

  6. TVAR modeling of EEG to detect audio distraction during simulated driving

    NASA Astrophysics Data System (ADS)

    Dahal, Nabaraj; (Nanda Nandagopal, D.; Cocks, Bernadine; Vijayalakshmi, Ramasamy; Dasari, Naga; Gaertner, Paul

    2014-06-01

    Objective. The objective of our current study was to look for the EEG correlates that can reveal the engaged state of the brain while undertaking cognitive tasks. Specifically, we aimed to identify EEG features that could detect audio distraction during simulated driving. Approach. Time varying autoregressive (TVAR) analysis using Kalman smoother was carried out on short time epochs of EEG data collected from participants as they undertook two simulated driving tasks. TVAR coefficients were then used to construct all pole model enabling the identification of EEG features that could differentiate normal driving from audio distracted driving. Main results. Pole analysis of the TVAR model led to the visualization of event related synchronization/desynchronization (ERS/ERD) patterns in the form of pole displacements in pole plots of the temporal EEG channels in the z plane enabling the differentiation of the two driving conditions. ERS in the EEG data has been demonstrated during audio distraction as an associated phenomenon. Significance. Visualizing the ERD/ERS phenomenon in terms of pole displacement is a novel approach. Although ERS/ERD has previously been demonstrated as reliable when applied to motor related tasks, it is believed to be the first time that it has been applied to investigate human cognitive phenomena such as attention and distraction. Results confirmed that distracted/non-distracted driving states can be identified using this approach supporting its applicability to cognition research.

  7. Engrossed in conversation: the impact of cell phones on simulated driving performance.

    PubMed

    Beede, Kristen E; Kass, Steven J

    2006-03-01

    The current study examined the effects of cognitively distracting tasks on various measures of driving performance. Thirty-six college students with a median of 6 years of driving experience completed a driving history questionnaire and four simulated driving scenarios. The distraction tasks consisted of responding to a signal detection task and engaging in a simulated cell phone conversation. Driving performance was measured in terms of four categories of behavior: traffic violations (e.g., speeding, running stop signs), driving maintenance (e.g., standard deviation of lane position), attention lapses (e.g., stops at green lights, failure to visually scan for intersection traffic), and response time (e.g., time to step on brake in response to a pop-up event). Performance was significantly impacted in all four categories when drivers were concurrently talking on a hands-free phone. Performance on the signal detection task was poor and not significantly impacted by the phone task, suggesting that considerably less attention was paid to detecting these peripheral signals. However, the signal detection task did interact with the phone task on measures of average speed, speed variability, attention lapses, and reaction time. The findings lend further empirical support of the dangers of drivers being distracted by cell phone conversations.

  8. A Novel Assessment of Braking Reaction Time Following THA Using a New Fully Interactive Driving Simulator.

    PubMed

    Ruel, Allison V; Lee, Yuo-Yu; Boles, John; Boettner, Friedrich; Su, Edwin; Westrich, Geoffrey H

    2015-07-01

    After total hip replacement surgery, patients are eager to resume the activities of daily life, particularly driving. Most surgeons recommend waiting 6 weeks after surgery to resume driving; however, there is no evidence to indicate that patients cannot resume driving earlier. Our purpose was to evaluate when in the recovery period following THA that patients regain or improve upon their preoperative braking reaction time, allowing them to safely resume driving. We measured and compared pre- and postoperative braking reaction times of 90 patients from 3 different surgeons using a Fully Interactive Driving Simulator (Simulator Systems International, Tulsa, OK). We defined a return to safe braking reaction time as a return to a time value that is either equal to or less than the preoperative braking reaction time. Patients tested at 2 and 3 weeks after surgery had slower braking reaction times than preoperative times by an average of 0.069 and 0.009 s, respectively. At 4 weeks after surgery, however, patients improved their reaction times by 0.035 s (p = 0.0398). In addition, at 2, 3, and 4 weeks postoperatively, the results also demonstrated that patient less than 70 years of age recovered faster. Based upon the results of this study, most patients should be allowed to return to driving 4 weeks following minimally invasive primary total hip arthroplasty.

  9. The influence of drinking, texting, and eating on simulated driving performance.

    PubMed

    Irwin, Christopher; Monement, Sophie; Desbrow, Ben

    2015-01-01

    Driving is a complex task and distractions such as using a mobile phone for the purpose of text messaging are known to have a significant impact on driving. Eating and drinking are common forms of distraction that have received less attention in relation to their impact on driving. The aim of this study was to further explore and compare the effects of a variety of distraction tasks (i.e., text messaging, eating, drinking) on simulated driving. Twenty-eight healthy individuals (13 female) participated in a crossover design study involving 3 experimental trials (separated by ≥24 h). In each trial, participants completed a baseline driving task (no distraction) before completing a second driving task involving one of 3 different distraction tasks (drinking 400 mL water, drinking 400 mL water and eating a 6-inch Subway sandwich, drinking 400 mL water and composing 3 text messages). Primary outcome measures of driving consisted of standard deviation of lateral position (SDLP) and reaction time to auditory and visual critical events. Subjective ratings of difficulty in performing the driving tasks were also collected at the end of the study to determine perceptions of distraction difficulty on driving. Driving tasks involving texting and eating were associated with significant impairment in driving performance measures for SDLP compared to baseline driving (46.0 ± 0.08 vs. 41.3 ± 0.06 cm and 44.8 ± 0.10 vs. 41.6 ± 0.07 cm, respectively), number of lane departures compared to baseline driving (10.9 ± 7.8 vs. 7.6 ± 7.1 and 9.4 ± 7.5 vs. 7.1 ± 7.0, respectively), and auditory reaction time compared to baseline driving (922 ± 95 vs. 889 ± 104 ms and 933 ± 101 vs. 901 ± 103 ms, respectively). No difference in SDLP (42.7 ± 0.08 vs. 42.5 ± 0.07 cm), number of lane departures (7.6 ± 7.7 vs. 7.0 ± 6.8), or auditory reaction time (891 ± 98 and 885 ± 89 ms) was observed in the drive involving the drink-only condition compared to the corresponding baseline drive

  10. A study on the effects of fatigue driving and drunk driving on drivers' physical characteristics.

    PubMed

    Zhang, Xingjian; Zhao, Xiaohua; Du, Hongji; Rong, Jian

    2014-01-01

    The purpose of this study was to analyze the effects of fatigue driving and drunk driving on drivers' physical characteristics; to analyze the differences in drivers' physical characteristics affected by different kinds of fatigue; and to compare the differences in the effects of the 2 driving states, fatigue driving and drunk driving. Twenty-five participants' physical characteristics were collected under 5 controlled situations: normal, tired driving, drowsy driving, drowsiness + tired driving, and drunk driving. In this article, fatigue driving refers to tiredness and drowsiness and includes 3 situations: tired driving, drowsy driving, and drowsiness + tired driving. The drivers' physical characteristics were measured in terms of 9 parameters: systolic blood pressure (SBP), heart rate (HR), eyesight, dynamic visual acuity (DVA), time for dark adaption (TDA), reaction time to sound (RTS), reaction time to light (RTL), deviation of depth perception (DDP), and time deviation of speed anticipation (TDSA). They were analyzed using analysis of variance (ANOVA) with repeated measures. Binary logistical regression analysis was used to explain the relationship between drivers' physical characteristics and the two driving states. Most of the drivers' physical characteristic parameters were found to be significantly different under the influence of different situations. Four indicators are significantly affected by fatigue driving during deep fatigue (in decreasing order of influence): HR, RTL, SBP and RTS. HR and RTL are significant in the logistical regression model of the drowsiness + tired driving situation and normal situations. Six indicators of the drivers' physical characteristics are significantly affected by drunk driving (in decreasing order of influence): SBP, RTL, DDP, eyesight, RTS, and TDSA. SBP and DDP have a significant effect in the logistical regression model of the drunk driving situation and the normal situation. Both fatigue driving and drunk driving

  11. Simulated driving under the influence of extended wake, time of day and sleep restriction.

    PubMed

    Matthews, Raymond W; Ferguson, Sally A; Zhou, Xuan; Kosmadopoulos, Anastasi; Kennaway, David J; Roach, Gregory D

    2012-03-01

    Around a fifth of all road accidents can be attributed to fatigued drivers. Previous studies indicate that driving performance is influenced by time of day and decreases with sustained wakefulness. However, these influences occur naturally in unison, confounding their effects. Typically, when people drive at a poor time of day and with extended wake, their sleep is also restricted. Hence, the aim of the current study was to determine the independent effects of prior wake and time of day on driving performance under conditions of sleep restriction. The driving performance of fourteen male participants (21.8 ± 3.8 years, mean ± SD) was assessed during a 10 min simulated driving task with speed/lane mean, variability and violations (speeding and crashes) measured. Participants were tested at 2.5h intervals after waking, across 7 × 28 h days with a sleep:wake ratio of 1:5. By forced desynchrony each driving session occurred at 9 doses of prior wake and within 6 divisions of the circadian cycle based on core body temperature. A mixed models ANOVA revealed significant main effects of circadian phase, prior wake and sleep debt on lane violations. In addition, three significant two-way interactions (circadian phase × prior wake, prior wake × sleep debt, sleep debt × circadian phase) and one three-way interaction (circadian × prior wake × sleep debt) were identified. The presence of the large interaction effects shows that the influence of each factor is largely dependent on the magnitude of the other factors. For example, the presence of the time of day influence on driving performance is dependent on the length of prior wake or the presence of sleep debt. The findings suggest that people are able to undertake a low-difficulty simulated drive safely, at least for a short period, during their circadian nadir provided that they have had sufficient sleep and have not been awake too long.

  12. Driving Simulator Performance in Patients with Possible and Probable Alzheimer’s Disease

    PubMed Central

    Stein, Anthony C.; Dubinsky, Richard M.

    2011-01-01

    Drivers with more advanced stages of Alzheimer’s disease (AD) have been previously associated with an increased rate of motor vehicle accidents. Drivers suffering from early AD are also involved in, and may even cause motor vehicle accidents with greater frequency than “normal” drivers. Consequently there is considerable public concern regarding traffic safety issues for those with AD and subsequently for society, but there has been little research in understanding whether deterioration in driving ability is progressive, or has a sudden onset once the disease has reached a certain severity. The purpose of this study was to identify possible degradation in simulated driving performance that may occur at the earliest stages of AD, and compare these decrements to a control group of normal drivers. Using a single blind design, seventeen AD subjects, eight at a Clinical Dementia Rating (CDR) of 0.5 (possible AD) and nine at a CDR of 1 (probable AD), were compared to 63 cognitively normal, elderly controls. All subjects were trained to drive a computerized interactive driving simulator and then tested on a 19.3 km (12 mile) test course. The AD subjects demonstrated impaired driving performance when compared to the controls. The simulated driving performance of the CDR 1 AD subjects was so degraded that it would be regarded as unsafe by standard assessment criteria. The CDR 0.5 subjects made similar errors, suggesting that driving impairment may occur at the earliest stages of the disease. Further work will be necessary to determine the significance of these findings. PMID:22105407

  13. Age differences in simulated driving performance: compensatory processes.

    PubMed

    Andrews, E C; Westerman, S J

    2012-03-01

    In the context of driving, the reported experiment examines compensatory processes for age-related declines in cognitive ability. Younger (26-40 years) and older (60+ years) participants (n=22 each group) performed a car following task in a driving simulator. Several performance measures were recorded, including assessments of anticipation of unfolding traffic events. Participants also completed a range of measures of cognitive ability - including both fluid and crystallised abilities. Three examples of age-related compensation are reported: (i) older drivers adopted longer headways than younger drivers. Data were consistent with this being compensation for an age-related deficit in complex reaction time; (ii) older drivers with relatively higher cognitive ability anticipated traffic events more frequently, whereas the reverse pattern was found for younger drivers; and, (iii) older drivers with greater crystallised ability were less reliant on spatial ability to maintain lane position. Consistent with theories of 'cognitive reserve', interactions between crystallised ability and age for self-report workload suggested that compensation for age-related cognitive ability deficits required investment of additional effort. Results are considered in the context of the prospects of further assessment of older drivers.

  14. Integrated Plasma Simulation of Lower Hybrid Current Drive in Tokamaks

    NASA Astrophysics Data System (ADS)

    Bonoli, P. T.; Wright, J. C.; Harvey, R. W.; Batchelor, D. B.; Berry, L. A.; Kessel, C. E.; Jardin, S. C.

    2012-03-01

    It has been shown in Alcator C-Mod that the onset time for sawteeth can be delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through the injection of off-axis LH current drive power [1]. We are simulating these experiments using the Integrated Plasma Simulator (IPS) [2], where the driven LH current density profiles are computed using a ray tracing component (GENRAY) and Fokker Planck code (CQL3D) [3] that are run in a tightly coupled time advance. The background plasma is evolved using the TSC transport code with the Porcelli sawtooth model [4]. Predictions of the driven LH current profiles will be compared with simpler ``reduced'' models for LHCD such as the LSC code which is implemented in TSC and which is also invoked within the IPS. [4pt] [1] C. E. Kessel et al, Bull. of the Am. Phys. Soc. 53, Poster PP6.00074 (2008). [0pt] [2] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008). [0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Meeting on Simulation and Modeling of Therm. Plasmas, Montreal, Canada (1992). [0pt] [4] S. C. Jardin et al, J. Comp. Phys. 66, 481 (1986).

  15. Behavioral and Cardiovascular Responses to Frustration during Simulated Driving Tasks in Young Adults with and without Attention Disorder Symptoms

    ERIC Educational Resources Information Center

    Oliver, Michele L.; Nigg, Joel T.; Cassavaugh, Nicholas D.; Backs, Richard W.

    2012-01-01

    Objective: The present study examined the role of negative emotions on driving performance in relation to ADHD, by comparing young adults scoring high on measures of ADHD (n = 20) with a control group (n = 22). Method: The authors used cardiorespiratory physiological measures, simulated driving behavior, and self-report to examine how participants…

  16. Behavioral and Cardiovascular Responses to Frustration during Simulated Driving Tasks in Young Adults with and without Attention Disorder Symptoms

    ERIC Educational Resources Information Center

    Oliver, Michele L.; Nigg, Joel T.; Cassavaugh, Nicholas D.; Backs, Richard W.

    2012-01-01

    Objective: The present study examined the role of negative emotions on driving performance in relation to ADHD, by comparing young adults scoring high on measures of ADHD (n = 20) with a control group (n = 22). Method: The authors used cardiorespiratory physiological measures, simulated driving behavior, and self-report to examine how participants…

  17. The useful field of view assessment predicts simulated commercial motor vehicle driving safety.

    PubMed

    McManus, Benjamin; Heaton, Karen; Vance, David E; Stavrinos, Despina

    2016-10-02

    The Useful Field of View (UFOV) assessment, a measure of visual speed of processing, has been shown to be a predictive measure of motor vehicle collision (MVC) involvement in an older adult population, but it remains unknown whether UFOV predicts commercial motor vehicle (CMV) driving safety during secondary task engagement. The purpose of this study is to determine whether the UFOV assessment predicts simulated MVCs in long-haul CMV drivers. Fifty licensed CMV drivers (Mage = 39.80, SD = 8.38, 98% male, 56% Caucasian) were administered the 3-subtest version of the UFOV assessment, where lower scores measured in milliseconds indicated better performance. CMV drivers completed 4 simulated drives, each spanning approximately a 22.50-mile distance. Four secondary tasks were presented to participants in a counterbalanced order during the drives: (a) no secondary task, (b) cell phone conversation, (c) text messaging interaction, and (d) e-mailing interaction with an on-board dispatch device. The selective attention subtest significantly predicted simulated MVCs regardless of secondary task. Each 20 ms slower on subtest 3 was associated with a 25% increase in the risk of an MVC in the simulated drive. The e-mail interaction secondary task significantly predicted simulated MVCs with a 4.14 times greater risk of an MVC compared to the no secondary task condition. Subtest 3, a measure of visual speed of processing, significantly predicted MVCs in the email interaction task. Each 20 ms slower on subtest 3 was associated with a 25% increase in the risk of an MVC during the email interaction task. The UFOV subtest 3 may be a promising measure to identify CMV drivers who may be at risk for MVCs or in need of cognitive training aimed at improving speed of processing. Subtest 3 may also identify CMV drivers who are particularly at risk when engaged in secondary tasks while driving.

  18. Effects of distraction task on driving: a functional magnetic resonance imaging study.

    PubMed

    Chung, Soon-Cheol; Choi, Mi-Hyun; Kim, Hyung-Sik; You, Na-Rae; Hong, Sang-Pyo; Lee, Jung-Chul; Park, Sung-Jun; Baek, Ji-Hye; Jeong, Ul-Ho; You, Ji-Hye; Lim, Dae-Woon; Kim, Hyun-Jun

    2014-01-01

    This study investigated neuronal activation differences under two conditions: driving only and distracted driving. Driving and distraction tasks were performed using a Magnetic Resonance (MR)-compatible driving simulator with a driving wheel and pedal. The experiment consisted of three blocks, and each block had both a Rest phase (1 min) and a Driving phase (2 min). During the Rest phase, drivers were instructed to simply look at the stop screen without performing any driving tasks. During the Driving phase, each driver was required to drive at 110 km/h under two conditions: driving only and driving while performing additional distraction tasks. The results show that the precuneus, inferior parietal lobule, supramarginal gyrus, middle frontal gyrus, cuneus, and declive are less activated in distracted driving than in driving only. These regions are responsible for spatial perception, spatial attention, visual processing and motor control. However, the cingulate gyrus and sub-lobar regions (lentiform nucleus and caudate), which are responsible for error monitoring and control of unnecessary movement, show increased activation during distracted driving compared with driving only.

  19. Driving Simulator Performance Remains Impaired In Patients With Severe OSA after CPAP Treatment

    PubMed Central

    Vakulin, Andrew; Baulk, Stuart D.; Catcheside, Peter G.; Antic, Nick A.; van den Heuvel, Cameron J.; Dorrian, Jillian; McEvoy, R. Doug

    2011-01-01

    Study Objectives: To assess the effectiveness of CPAP treatment in improving 90-minute driving simulator performance in severe OSA patients compared to age/gender matched controls. Design: Driving simulator performance was assessed at baseline and 3 months later, with OSA patients treated with CPAP during the interval. Setting: University Teaching Hospital. Participants: Patients with severe OSA (n = 11) and control subjects without OSA (n = 9). Interventions: CPAP Measurements and Results: Simulator driving parameters of steering deviation, braking reaction time and crashes were measured at baseline and ∼3 months follow-up. At baseline, OSA subjects demonstrated significantly greater steering deviation compared to controls (mean [95% CI], OSA group, 49.9 cm [43.7 to 56.0 cm] vs control group, 34.9 cm [28.1 to 41.7 cm], p = 0.003). Following ∼3 months of CPAP treatment (mean ± SD 6.0 ± 1.4 h/night), steering deviation in OSA subjects improved by an average of 3.1 cm (CI, 1.4 to 4.9), p < 0.001, while no significant steering changes were observed in the control group. Despite the improvement, steering deviation in the OSA group remained significantly higher than in controls (OSA group, 46.7 cm [CI, 40.6 to 52.8 cm] vs control group, 36.1 cm [CI, 29.3 to 42.9 cm], p = 0.025). Conclusions: While driving simulator performance improved after ∼3 months of CPAP treatment with high adherence in patients with severe OSA, performance remained impaired compared to control subjects. These results add to the growing body of evidence that some neurobehavioral deficits in patients with severe OSA are not fully reversed by treatment. Further studies are needed to assess causes of residual driving simulator impairment and to determine whether this is associated with persistent elevated real-life accident risk. Trial Registration: Data presented in this manuscript was collected as part of a clinical trial “Experimental Investigations of Driving Impairment in Obstructive

  20. Assessments of risky driving: a Go/No-Go simulator driving task to evaluate risky decision-making and associated behavioral patterns.

    PubMed

    Ba, Yutao; Zhang, Wei; Salvendy, Gavriel; Cheng, Andy S K; Ventsislavova, Petya

    2016-01-01

    This study sought to develop and validate a Go/No-Go Simulator Driving Task (G/NG-SDT) to evaluate driver risky decision-making and associated behavioral assessments at a situation-specific level. Eighty-four participants were instructed to complete a route in as short time as possible, but avoiding any violations or crashes. To achieve this aim, they had to decide to go or wait in the dilemma scenes, paired with the baseline scenes in several scenarios. High-risk drivers with more Go decisions demonstrated more violations, in both simulator tasks and real road driving, as well as higher scores of Driving Behavior Questionnaire (DBQ) violations and more Balloon Analogue Risk Task (BART) pumps. These high-risk drivers also showed distinguishable behavioral patterns in simulator driving, moderated by the specific driving situations (e.g. scenario and scene). Several behavior assessments were consistently distinguishable in all tested situations, qualified as robust indictors to predict risk-taking in more general driving situations.

  1. Recovery and simulated driving after intravenous anesthesia with thiopental, methohexital, propanidid, or alphadione.

    PubMed

    Korttila, K; Linnoila, M; Ertama, P; Häkkinen, S

    1975-09-01

    Recovery from anesthesia was assessed in a double-bind manner in 40 healthy volunteer students after intravenous anesthesia with thiopental (6.0 mg/kg), methohexital (2.0 mg/kg), propanidid (6.6 mg/kg), or alphadione (Althesin), 85 mul/kg using a driving simulator 2,4, 6, and 8 hours after injection of the drugs. Clinical recovery was faster after propanidid and methohexital than after thiopental or alphadione. Driving performances remained significantly (P less than 0.05) worse than in a control group for 6 hours after thiopental and for 8 hours after methohexital, and reaction times 8 hours after thiopental remained worse than in the control subjects. After alphadione driving skills were impaired at 6 hours only. Propanidid produced no impairment in driving skills at any time during the experiment. It is concluded that after the doses used in this study patients should not drive or operate machinery for at least 2 hours after propanidid and for at least 8 hours after alphadione. After methohexital and thiopental patients should probably not drive for 24 hours because of the severity of the disturbances at 8 hours.

  2. Direct drive: Simulations and results from the National Ignition Facility

    SciTech Connect

    Radha, P. B.; Hohenberger, M.; Edgell, D. H.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Rosenberg, M. J.; Seka, W.; Shvydky, A.; Boehly, T. R.; Collins, T. J. B.; Campbell, E. M.; Craxton, R. S.; Delettrez, J. A.; Dixit, S. N.; Frenje, J. A.; Froula, D. H.; Goncharov, V. N.; Hu, S. X.; Knauer, J. P.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Moody, J.; Myatt, J. F.; Petrasso, R. D.; Regan, S. P.; Sangster, T. C.; Sio, H.; Skupsky, S.; Zylstra, A.

    2016-04-19

    Here, the direct-drive implosion physics is being investigated at the National Ignition Facility. The primary goal of the experiments is twofold: to validate modeling related to implosion velocity and to estimate the magnitude of hot-electron preheat. Implosion experiments indicate that the energetics is well-modeled when cross-beam energy transfer (CBET) is included in the simulation and an overall multiplier to the CBET gain factor is employed; time-resolved scattered light and scattered-light spectra display the correct trends. Trajectories from backlit images are well modeled, although those from measured self-emission images indicate increased shell thickness and reduced shell density relative to simulations. Sensitivity analyses indicate that the most likely cause for the density reduction is nonuniformity growth seeded by laser imprint and not laser-energy coupling. Hot-electron preheat is at tolerable levels in the ongoing experiments, although it is expected to increase after the mitigation of CBET. Future work will include continued model validation, imprint measurements, and mitigation of CBET and hot-electron preheat.

  3. Direct drive: Simulations and results from the National Ignition Facility

    DOE PAGES

    Radha, P. B.; Hohenberger, M.; Edgell, D. H.; ...

    2016-04-19

    Here, the direct-drive implosion physics is being investigated at the National Ignition Facility. The primary goal of the experiments is twofold: to validate modeling related to implosion velocity and to estimate the magnitude of hot-electron preheat. Implosion experiments indicate that the energetics is well-modeled when cross-beam energy transfer (CBET) is included in the simulation and an overall multiplier to the CBET gain factor is employed; time-resolved scattered light and scattered-light spectra display the correct trends. Trajectories from backlit images are well modeled, although those from measured self-emission images indicate increased shell thickness and reduced shell density relative to simulations. Sensitivitymore » analyses indicate that the most likely cause for the density reduction is nonuniformity growth seeded by laser imprint and not laser-energy coupling. Hot-electron preheat is at tolerable levels in the ongoing experiments, although it is expected to increase after the mitigation of CBET. Future work will include continued model validation, imprint measurements, and mitigation of CBET and hot-electron preheat.« less

  4. Direct drive: Simulations and results from the National Ignition Facility

    SciTech Connect

    Radha, P. B.; Hohenberger, M.; Edgell, D. H.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Rosenberg, M. J.; Seka, W.; Shvydky, A.; Boehly, T. R.; Collins, T. J. B.; Campbell, E. M.; Craxton, R. S.; Delettrez, J. A.; Dixit, S. N.; Frenje, J. A.; Froula, D. H.; Goncharov, V. N.; Hu, S. X.; Knauer, J. P.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Moody, J.; Myatt, J. F.; Petrasso, R. D.; Regan, S. P.; Sangster, T. C.; Sio, H.; Skupsky, S.; Zylstra, A.

    2016-04-19

    Here, the direct-drive implosion physics is being investigated at the National Ignition Facility. The primary goal of the experiments is twofold: to validate modeling related to implosion velocity and to estimate the magnitude of hot-electron preheat. Implosion experiments indicate that the energetics is well-modeled when cross-beam energy transfer (CBET) is included in the simulation and an overall multiplier to the CBET gain factor is employed; time-resolved scattered light and scattered-light spectra display the correct trends. Trajectories from backlit images are well modeled, although those from measured self-emission images indicate increased shell thickness and reduced shell density relative to simulations. Sensitivity analyses indicate that the most likely cause for the density reduction is nonuniformity growth seeded by laser imprint and not laser-energy coupling. Hot-electron preheat is at tolerable levels in the ongoing experiments, although it is expected to increase after the mitigation of CBET. Future work will include continued model validation, imprint measurements, and mitigation of CBET and hot-electron preheat.

  5. EMERGENCY BRAKING IN ADULTS VERSUS NOVICE TEEN DRIVERS: RESPONSE TO SIMULATED SUDDEN DRIVING EVENTS

    PubMed Central

    Kandadai, Venk; McDonald, Catherine C.; Winston, Flaura K.

    2015-01-01

    Motor vehicle crashes remain the leading cause of death in teens in the United States. Newly licensed drivers are the group most at risk for crashes. Their driving skills are very new, still very often untested, so that their ability to properly react in an emergency situation remains a research question. Since it is impossible to expose human subjects to critical life threatening driving scenarios, researchers have been increasingly using driving simulators to assess driving skills. This paper summarizes the results of a driving scenario in a study comparing the driving performance of novice teen drivers (n=21) 16–17 year olds with 90 days of provisional licensure with that of experienced adult drivers (n=17) 25–50 year olds with at least 5 years of PA licensure, at least 100 miles driven per week and no self-reported collisions in the previous 3 years. As part of a 30 to 35 simulated drive that encompassed the most common scenarios that result in serious crashes, participants were exposed to a sudden car event. As the participant drove on a suburban road, a car surged from a driveway hidden by a fence on the right side of the road. To avoid the crash, participants must hard brake, exhibiting dynamic control over both attentional and motor resources. The results showed strong differences between the experienced adult and novice teen drivers in the brake pressure applied. When placed in the same situation, the novice teens decelerated on average 50% less than the experienced adults (p<0.01). PMID:26709330

  6. EMERGENCY BRAKING IN ADULTS VERSUS NOVICE TEEN DRIVERS: RESPONSE TO SIMULATED SUDDEN DRIVING EVENTS.

    PubMed

    Loeb, Helen S; Kandadai, Venk; McDonald, Catherine C; Winston, Flaura K

    Motor vehicle crashes remain the leading cause of death in teens in the United States. Newly licensed drivers are the group most at risk for crashes. Their driving skills are very new, still very often untested, so that their ability to properly react in an emergency situation remains a research question. Since it is impossible to expose human subjects to critical life threatening driving scenarios, researchers have been increasingly using driving simulators to assess driving skills. This paper summarizes the results of a driving scenario in a study comparing the driving performance of novice teen drivers (n=21) 16-17 year olds with 90 days of provisional licensure with that of experienced adult drivers (n=17) 25-50 year olds with at least 5 years of PA licensure, at least 100 miles driven per week and no self-reported collisions in the previous 3 years. As part of a 30 to 35 simulated drive that encompassed the most common scenarios that result in serious crashes, participants were exposed to a sudden car event. As the participant drove on a suburban road, a car surged from a driveway hidden by a fence on the right side of the road. To avoid the crash, participants must hard brake, exhibiting dynamic control over both attentional and motor resources. The results showed strong differences between the experienced adult and novice teen drivers in the brake pressure applied. When placed in the same situation, the novice teens decelerated on average 50% less than the experienced adults (p<0.01).

  7. Predicting Motor Vehicle Collisions in a Driving Simulator in Young Adults Using the Useful Field of View Assessment

    PubMed Central

    McManus, Benjamin; Cox, Molly K.; Vance, David E.; Stavrinos, Despina

    2015-01-01

    Objective Being involved in motor vehicle collisions is the leading cause of death in 1 to 34 year olds, and risk is particularly high in young adults. The Useful Field of View (UFOV) task, a cognitive measure of processing speed, divided attention, and selective attention, has been shown to be predictive of motor vehicle collisions in older adults, but its use as a predictor of driving performance in a young adult population has not been investigated. The present study examined whether UFOV was a predictive measure of motor vehicle collisions in a driving simulator in a young adult population. Method The 3-subtest version of UFOV (lower scores measured in milliseconds indicate better performance) was administered to 60 college students. Participants also completed an 11-mile simulated drive to provide driving performance metrics. Results Findings suggested that subtests 1 and 2 suffered from a ceiling effect. UFOV subtest 3 significantly predicted collisions in the simulated drive. Each 30 milliseconds slower on the subtest was associated with nearly a 10% increase in the risk of a simulated collision. Post-hoc analyses revealed a small partially mediating effect of subtest 3 on the relationship between driving experience and collisions. Conclusion The selective attention component of UFOV subtest 3 may be a predictive measure of crash involvement in a young adult population. Improvements in selective attention may be the underlying mechanism in how driving experience improves driving performance. PMID:25794266

  8. Detecting Driver Mental Fatigue Based on EEG Alpha Power Changes during Simulated Driving

    PubMed Central

    GHARAGOZLOU, Faramarz; NASL SARAJI, Gebraeil; MAZLOUMI, Adel; NAHVI, Ali; MOTIE NASRABADI, Ali; RAHIMI FOROUSHANI, Abbas; ARAB KHERADMAND, Ali; ASHOURI, Mohammadreza; SAMAVATI, Mehdi

    2015-01-01

    Background: Driver fatigue is one of the major implications in transportation safety and accounted for up to 40% of road accidents. This study aimed to analyze the EEG alpha power changes in partially sleep-deprived drivers while performing a simulated driving task. Methods: Twelve healthy male car drivers participated in an overnight study. Continuous EEG and EOG records were taken during driving on a virtual reality simulator on a monotonous road. Simultaneously, video recordings from the driver face and behavior were performed in lateral and front views and rated by two trained observers. Moreover, the subjective self-assessment of fatigue was implemented in every 10-min interval during the driving using Fatigue Visual Analog Scale (F-VAS). Power spectrum density and fast Fourier transform (FFT) were used to determine the absolute and relative alpha powers in the initial and final 10 minutes of driving. Results: The findings showed a significant increase in the absolute alpha power (P = 0.006) as well as F-VAS scores during the final section of driving (P = 0.001). Meanwhile, video ratings were consistent with subjective self-assessment of fatigue. Conclusion: The increase in alpha power in the final section of driving indicates the decrease in the level of alertness and attention and the onset of fatigue, which was consistent with F-VAS and video ratings. The study suggested that variations in alpha power could be a good indicator for driver mental fatigue, but for using as a countermeasure device needed further investigations. PMID:26811821

  9. Accuracy of self-evaluation in adults with ADHD: evidence from a driving study.

    PubMed

    Knouse, Laura E; Bagwell, Catherine L; Barkley, Russell A; Murphy, Kevin R

    2005-05-01

    Research on children with ADHD indicates an association with inaccuracy of self-appraisal. This study examines the accuracy of self-evaluations in clinic-referred adults diagnosed with ADHD. Self-assessments and performance measures of driving in naturalistic settings and on a virtual-reality driving simulator are used to assess accuracy of self-evaluations. The group diagnosed with ADHD (n= 44) has a higher rate of collisions, speeding tickets, and total driving citations in their driving history; report less use of safe driving behaviors in naturalistic settings; and use fewer safe driving behaviors in the simulator than the community comparison group (n= 44). Despite poorer performance, adults with ADHD provide similar driving self-assessments, thereby overestimating in naturalistic settings to a greater degree than the comparison group. These findings extend research in children with ADHD to an adult sample in an important domain of functioning and may relate to findings of executive deficits associated with ADHD.

  10. Use of a driving simulator to assess performance under adverse weather conditions in adults with albinism.

    PubMed

    Hofman, Gwen M; Summers, C Gail; Ward, Nicholas; Bhargava, Esha; Rakauskas, Michael E; Holleschau, Ann M

    2012-04-01

    Participants with albinism have reduced vision and nystagmus with reduced foveation times. This prospective study evaluated driving in 12 participants with albinism and 12 matched controls. Participants drove a vehicle simulator through a virtual rural course in sunny and foggy conditions. Under sunny conditions, participants with albinism showed a narrower preferred minimum safety boundary during car-following tasks than did controls, but there was no difference under foggy conditions. Their driving did not differ significantly from that of controls when approaching a stop sign or when choosing gap size between oncoming vehicles when crossing an intersection. However, when compared to control drivers, participants with albinism had a decreased minimum safety boundary for car-following that should be included in counseling regarding driving safety.

  11. Distractions N' Driving: video game simulation educates young drivers on the dangers of texting while driving.

    PubMed

    Saqer, Haneen; de Visser, Ewart; Strohl, Jonathan; Parasuraman, Raja

    2012-01-01

    The proliferation of portable communication and entertainment devices has introduced new dangers to the driving environment, particularly for young and inexperienced drivers. Graduate students from George Mason University illustrate a powerful, practical, and cost-effective program that has been successful in educating these drivers on the dangers of texting while driving, which can easily be adapted and implemented in other communities.

  12. Effects of two doses of alcohol on simulator driving performance in adults with attention-deficit/hyperactivity disorder.

    PubMed

    Barkley, Russell A; Murphy, Kevin R; O'Connell, Trisha; Anderson, Deborah; Connor, Daniel F

    2006-01-01

    Prior studies have documented greater impairments in driving performance and greater alcohol consumption among adults with attention-deficit/hyperactivity disorder (ADHD). This study examined whether alcohol consumption produces a differentially greater impairment in driving among adults with ADHD in comparison to a community control group. The present study compared 50 adults with ADHD (mean age 33 years) and 40 control adults (mean age 29 years) on the effects of 2 single, acute doses of alcohol (0.04 and 0.08 blood alcohol concentration) and a placebo on their driving performance. The authors used a virtual reality driving simulator, examiner and self-ratings of simulator performance, and a continuous performance test (CPT) to evaluate attention and inhibition. Approximately half of the adults in each group were randomized to either the low or high dose alcohol treatment arms. Alcohol consumption produced a greater impact on the CPT inattention measures of the ADHD than the control group. Similar results were obtained for the behavioral observations taken during the operation of the driving simulator. Driving simulator scores, however, showed mainly a deleterious effect of alcohol on all participants but no differentially greater effect on the ADHD group. The present results demonstrated that alcohol may have a greater detrimental effect on some aspects of driving performance in ADHD than control adults.

  13. The use of a driving simulator to determine how time pressures impact driver aggressiveness.

    PubMed

    Fitzpatrick, Cole D; Samuel, Siby; Knodler, Michael A

    2017-08-31

    Speeding greatly attributes to traffic safety with approximately a third of fatal crashes in the United States being speeding-related. Previous research has identified being late as a primary cause of speeding. In this driving simulator study, a virtual drive was constructed to evaluate how time pressures, or hurried driving, affected driver speed choice and driver behavior. In particular, acceleration profiles, gap acceptance, willingness to pass, and dilemma zone behavior were used, in addition to speed, as measures to evaluate whether being late increased risky and aggressive driving behaviors. Thirty-six drivers were recruited with an equal male/female split and a broad distribution of ages. Financial incentives and completion time goals calibrated from a control group were used to generate a Hurried and Very Hurried experimental group. As compared to the control group, Very Hurried drivers selected higher speeds, accelerated faster after red lights, accepted smaller gaps on left turns, were more likely to pass a slow vehicle, and were more likely to run a yellow light in a dilemma zone situation. These trends were statistically significant and were also evident with the Hurried group but a larger sample would be needed to show statistical significance. The findings from this study provide evidence that hurried drivers select higher speeds and exhibit riskier driving behaviors. These conclusive results have possible implications in areas such as transportation funding and commercial motor vehicle safety. Published by Elsevier Ltd.

  14. Effects of two doses of methylphenidate on simulator driving performance in adults with attention deficit hyperactivity disorder.

    PubMed

    Barkley, Russell A; Murphy, Kevin R; O'Connell, Trisha; Connor, Daniel F

    2005-01-01

    Numerous studies have documented an increased frequency of vehicular crashes, traffic citations, driving performance deficits, and driving-related cognitive impairments in teens and adults with attention deficit hyperactivity disorder. The present study evaluated the effects of two single, acute doses of methylphenidate (10 and 20 mg) and a placebo on the driving performance of 53 adults with ADHD (mean age=37 years, range=18-65) using a virtual reality driving simulator, examiner and self-ratings of simulator performance, and a continuous performance test (CPT) to evaluate attention and inhibition. A double-blind, drug-placebo, within-subjects crossover design was used in which all participants were tested at baseline and then experienced all three drug conditions. A significant beneficial effect for the high dose of medication was observed on impulsiveness on CPT, variability of steering in the standard driving course, and driving speed during the obstacle course. A beneficial effect of the low dose of medication also was evident on turn signal use during the standard driving course. An apparent practice effect was noted on some of the simulator measures between the baseline and subsequent testing sessions that may have interacted with and thereby obscured drug effects on those measures. The results, when placed in the context of prior studies of stimulants on driving performance, continue to recommend their clinical use as one means of reducing the driving risks in ADHD teens and adults. Given the significantly higher risk of adverse driving outcomes associated with ADHD, industry needs to better screen for ADHD among employees who drive as part of employment so as to improve safety and reduce costs. Use of stimulants to treat the adult ADHD driver may reduce safety risks.

  15. The impact of Stereotype Threat on the simulated driving performance of older drivers.

    PubMed

    Joanisse, Mélanie; Gagnon, Sylvain; Voloaca, Mihnea

    2013-01-01

    Older drivers are perceived as being dangerous and overly cautious by other drivers. We tested the hypothesis that this negative stereotype has a direct influence on the performance of older drivers. Based on the Stereotype Threat literature, we predicted that older driving performance would be altered after exposure to a Stereotype Threat. Sixty-one older drivers aged 65 and above completed a simulated driving assessment course. Prior to testing, half of the participants were told that the objective of the study was to investigate why older adults aged 65 and above were more implicated in on-road accidents (Stereotype Threat condition) and half were showed a neutral statement. Results confirmed that exposure to the threat significantly altered driving performance. Older adults in the Stereotype Threat condition made more driving mistakes than those in the control group. Interestingly, under a Stereotype Threat condition, older adults tended to commit more speeding infractions. We also observed that domain identification (whether driving is deemed important or not) moderated the impact of the threat. Taken together, these results support recent older drivers' performance models suggesting that the interaction between individual and social factors need to be considered when examining older drivers' performance.

  16. Time-of-day mediates the influences of extended wake and sleep restriction on simulated driving.

    PubMed

    Matthews, Raymond W; Ferguson, Sally A; Zhou, Xuan; Sargent, Charli; Darwent, David; Kennaway, David J; Roach, Gregory D

    2012-06-01

    Although a nonlinear time-of-day and prior wake interaction on performance has been well documented, two recent studies have aimed to incorporate the influences of sleep restriction into this paradigm. Through the use of sleep-restricted forced desynchrony protocols, both studies reported a time-of-day × sleep restriction interaction, as well as a time-of-day × prior wake × sleep dose three-way interaction. The current study aimed to investigate these interactions on simulated driving performance, a more complex task with ecological validity for the problem of fatigued driving. The driving performance of 41 male participants (mean ± SD: 22.8 ±2.2 yrs) was assessed on a 10-min simulated driving task with the standard deviation of lateral position (SDLAT) measured. Using a between-group design, participants were subjected to either a control condition of 9.33 h of sleep/18.66 h of wake, a moderate sleep-restriction (SR) condition of 7 h of sleep/21 h of wake, or a severe SR condition of 4.66 h of sleep/23.33 h of wake. In each condition, participants were tested at 2.5-h intervals after waking across 7 × 28-h d of forced desynchrony. Driving sessions occurred at nine doses of prior wake, within six divisions of the circadian cycle based on core body temperature (CBT). Mixed-models analyses of variance (ANOVAs) revealed significant main effects of time-of-day, prior wake, sleep debt, and sleep dose on SDLAT. Additionally, significant two-way interactions of time-of-day × prior wake and time-of-day × sleep debt, as well as significant three-way interactions of time-of-day × prior wake × sleep debt and time-of-day × sleep debt × sleep dose were observed. Although limitations such as the presence of practice effects and large standard errors are noted, the study concludes with three findings. The main effects demonstrate that extending wake, reducing sleep, and driving at poor times of day all significantly impair driving performance at an individual

  17. Driving simulator performance of veterans from the Iraq and Afghanistan wars.

    PubMed

    Amick, Melissa M; Kraft, Melissa; McGlinchey, Regina

    2013-01-01

    Driving simulator performance was examined in Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) Veterans to objectively evaluate driving abilities among this cohort who self-report poorer driving safety postdeployment. OIF/OEF Veterans (n = 25) and age- and education-matched civilian controls (n = 25) participated in a 30 min driving simulator assessment that measured the frequency of minor, moderate, and severe driving errors. Frequency of errors in specific content domains (speed regulation, positioning, and signaling) was also calculated. All participants answered questions about number of lifetime traffic "warnings," moving violation tickets, and accidents. Veterans completed the Posttraumatic Stress Disorder (PTSD) Checklist-Military Version. On the driving simulator assessment, Veterans committed more minor, moderate, severe, and speeding errors and reported poorer lifetime driving records than the civilian control group. Exploratory analyses revealed an association between increasing errors on the driving simulator with increasing symptoms of PTSD, although statistically this correlation did not reach significance. These findings suggest that Veterans perform more poorly on an objective evaluation of driving safety and that the presence of PTSD could be associated with worse performance on this standardized driving simulator assessment.

  18. Testing thermal gradient driving force for grain boundary migration using molecular dynamics simulations

    SciTech Connect

    Bai, Xian-Ming; Zhang, Yongfeng; Tonks, Michael R.

    2015-02-01

    Strong thermal gradients in low-thermal-conductivity ceramics may drive extended defects, such as grain boundaries and voids, to migrate in preferential directions. In this work, molecular dynamics simulations are conducted to study thermal gradient driven grain boundary migration and to verify a previously proposed thermal gradient driving force equation, using uranium dioxide as a model system. It is found that a thermal gradient drives grain boundaries to migrate up the gradient and the migration velocity increases under a constant gradient owing to the increase in mobility with temperature. Different grain boundaries migrate at very different rates due to their different intrinsic mobilities. The extracted mobilities from the thermal gradient driven simulations are compared with those calculated from two other well-established methods and good agreement between the three different methods is found, demonstrating that the theoretical equation of the thermal gradient driving force is valid, although a correction of one input parameter should be made. The discrepancy in the grain boundary mobilities between modeling and experiments is also discussed.

  19. Brain activity during driving with distraction: an immersive fMRI study.

    PubMed

    Schweizer, Tom A; Kan, Karen; Hung, Yuwen; Tam, Fred; Naglie, Gary; Graham, Simon J

    2013-01-01

    Non-invasive measurements of brain activity have an important role to play in understanding driving ability. The current study aimed to identify the neural underpinnings of human driving behavior by visualizing the areas of the brain involved in driving under different levels of demand, such as driving while distracted or making left turns at busy intersections. To capture brain activity during driving, we placed a driving simulator with a fully functional steering wheel and pedals in a 3.0 Tesla functional magnetic resonance imaging (fMRI) system. To identify the brain areas involved while performing different real-world driving maneuvers, participants completed tasks ranging from simple (right turns) to more complex (left turns at busy intersections). To assess the effects of driving while distracted, participants were asked to perform an auditory task while driving analogous to speaking on a hands-free device and driving. A widely distributed brain network was identified, especially when making left turns at busy intersections compared to more simple driving tasks. During distracted driving, brain activation shifted dramatically from the posterior, visual and spatial areas to the prefrontal cortex. Our findings suggest that the distracted brain sacrificed areas in the posterior brain important for visual attention and alertness to recruit enough brain resources to perform a secondary, cognitive task. The present findings offer important new insights into the scientific understanding of the neuro-cognitive mechanisms of driving behavior and lay down an important foundation for future clinical research.

  20. Brain activity during driving with distraction: an immersive fMRI study

    PubMed Central

    Schweizer, Tom A.; Kan, Karen; Hung, Yuwen; Tam, Fred; Naglie, Gary; Graham, Simon J.

    2013-01-01

    Introduction: Non-invasive measurements of brain activity have an important role to play in understanding driving ability. The current study aimed to identify the neural underpinnings of human driving behavior by visualizing the areas of the brain involved in driving under different levels of demand, such as driving while distracted or making left turns at busy intersections. Materials and Methods: To capture brain activity during driving, we placed a driving simulator with a fully functional steering wheel and pedals in a 3.0 Tesla functional magnetic resonance imaging (fMRI) system. To identify the brain areas involved while performing different real-world driving maneuvers, participants completed tasks ranging from simple (right turns) to more complex (left turns at busy intersections). To assess the effects of driving while distracted, participants were asked to perform an auditory task while driving analogous to speaking on a hands-free device and driving. Results: A widely distributed brain network was identified, especially when making left turns at busy intersections compared to more simple driving tasks. During distracted driving, brain activation shifted dramatically from the posterior, visual and spatial areas to the prefrontal cortex. Conclusions: Our findings suggest that the distracted brain sacrificed areas in the posterior brain important for visual attention and alertness to recruit enough brain resources to perform a secondary, cognitive task. The present findings offer important new insights into the scientific understanding of the neuro-cognitive mechanisms of driving behavior and lay down an important foundation for future clinical research. PMID:23450757

  1. Development and user validation of driving tasks for a power wheelchair simulator.

    PubMed

    Archambault, Philippe S; Blackburn, Émilie; Reid, Denise; Routhier, François; Miller, William C

    2017-07-01

    Mobility is important for participation in daily activities and a power wheelchair (PW) can improve quality of life of individuals with mobility impairments. A virtual reality simulator may be helpful in complementing PW skills training, which is generally seen as insufficient by both clinicians and PW users. To this end, specific, ecologically valid activities, such as entering an elevator and navigating through a shopping mall crowd, have been added to the McGill wheelchair (miWe) simulator through a user-centred approach. The objective of this study was to validate the choice of simulated activities in a group of newly trained PW users. We recruited 17 new PW users, who practiced with the miWe simulator at home for two weeks. They then related their experience through the Short Feedback Questionnaire, the perceived Ease of Use Questionnaire, and semi-structured interviews. Participants in general greatly appreciated their experience with the simulator. During the interviews, this group made similar comments about the activities as our previous group of expert PW users had done. They also insisted on the importance of realism in the miWe activities, for their use in training. A PW simulator may be helpful if it supports the practice of activities in specific contexts (such as a bathroom or supermarket), to complement the basic skills training received in the clinic (such as driving forward, backward, turning, and avoiding obstacles). Implications for Rehabilitation New power wheelchair users appreciate practicing on a virtual reality simulator and find the experience useful when the simulated diving activities are realistic and ecologically valid. User-centred development can lead to simulated power wheelchair activities that adequately capture everyday driving challenges experienced in various environmental contexts.

  2. Accuracy of Self-Evaluation in Adults with ADHD: Evidence from a Driving Study

    ERIC Educational Resources Information Center

    Knouse, Laura E.; Bagwell, Catherine L.; Barkley, Russell A.; Murphy, Kevin R.

    2005-01-01

    Research on children with ADHD indicates an association with inaccuracy of self-appraisal. This study examines the accuracy of self-evaluations in clinic-referred adults diagnosed with ADHD. Self-assessments and performance measures of driving in naturalistic settings and on a virtual-reality driving simulator are used to assess accuracy of…

  3. Accuracy of Self-Evaluation in Adults with ADHD: Evidence from a Driving Study

    ERIC Educational Resources Information Center

    Knouse, Laura E.; Bagwell, Catherine L.; Barkley, Russell A.; Murphy, Kevin R.

    2005-01-01

    Research on children with ADHD indicates an association with inaccuracy of self-appraisal. This study examines the accuracy of self-evaluations in clinic-referred adults diagnosed with ADHD. Self-assessments and performance measures of driving in naturalistic settings and on a virtual-reality driving simulator are used to assess accuracy of…

  4. Relationship Between Motor Vehicle Collisions and Results of Perimetry, Useful Field of View, and Driving Simulation in Drivers With Glaucoma

    PubMed Central

    Tatham, Andrew J.; Boer, Erwin R.; Gracitelli, Carolina P. B.; Rosen, Peter N.; Medeiros, Felipe A.

    2015-01-01

    Purpose: To examine the relationship between Motor Vehicle Collisions (MVCs) in drivers with glaucoma and standard automated perimetry (SAP), Useful Field of View (UFOV), and driving simulator assessment of divided attention. Methods: A cross-sectional study of 153 drivers from the Diagnostic Innovations in Glaucoma Study. All subjects had SAP and divided attention was assessed using UFOV and driving simulation using low-, medium-, and high-contrast peripheral stimuli presented during curve negotiation and car following tasks. Self-reported history of MVCs and average mileage driven were recorded. Results: Eighteen of 153 subjects (11.8%) reported a MVC. There was no difference in visual acuity but the MVC group was older, drove fewer miles, and had worse binocular SAP sensitivity, contrast sensitivity, and ability to divide attention (UFOV and driving simulation). Low contrast driving simulator tasks were the best discriminators of MVC (AUC 0.80 for curve negotiation versus 0.69 for binocular SAP and 0.59 for UFOV). Adjusting for confounding factors, longer reaction times to driving simulator divided attention tasks provided additional value compared with SAP and UFOV, with a 1 standard deviation (SD) increase in reaction time (approximately 0.75 s) associated with almost two-fold increased odds of MVC. Conclusions: Reaction times to low contrast divided attention tasks during driving simulation were significantly associated with history of MVC, performing better than conventional perimetric tests and UFOV. Translational Relevance: The association between conventional tests of visual function and MVCs in drivers with glaucoma is weak, however, tests of divided attention, particularly using driving simulation, may improve risk assessment. PMID:26046007

  5. Assessing fitness to drive-A validation study on patients with mild cognitive impairment.

    PubMed

    Fuermaier, Anselm B M; Piersma, Dafne; de Waard, Dick; Davidse, Ragnhild J; de Groot, Jolieke; Doumen, Michelle J A; Bredewoud, Ruud A; Claesen, René; Lemstra, Afina W; Scheltens, Philip; Vermeeren, Annemiek; Ponds, Rudolf; Verhey, Frans; Brouwer, Wiebo H; Tucha, Oliver

    2017-02-17

    There is no consensus yet on how to determine which patients with cognitive impairment are able to drive a car safely and which are not. Recently, a strategy was composed for the assessment of fitness to drive, consisting of clinical interviews, a neuropsychological assessment, and driving simulator rides, which was compared with the outcome of an expert evaluation of an on-road driving assessment. A selection of tests and parameters of the new approach revealed a predictive accuracy of 97.4% for the prediction of practical fitness to drive on an initial sample of patients with Alzheimer's dementia. The aim of the present study was to explore whether the selected variables would be equally predictive (i.e., valid) for a closely related group of patients; that is, patients with mild cognitive impairment (MCI). Eighteen patients with mild cognitive impairment completed the proposed approach to the measurement of fitness to drive, including clinical interviews, a neuropsychological assessment, and driving simulator rides. The criterion fitness to drive was again assessed by means of an on-road driving evaluation. The predictive validity of the fitness to drive assessment strategy was evaluated by receiver operating characteristic (ROC) analyses. Twelve patients with MCI (66.7%) passed and 6 patients (33.3%) failed the on-road driving assessment. The previously proposed approach to the measurement of fitness to drive achieved an overall predictive accuracy of 94.4% in these patients. The application of an optimal cutoff resulted in a diagnostic accuracy of 100% sensitivity toward unfit to drive and 83.3% specificity toward fit to drive. Further analyses revealed that the neuropsychological assessment and the driving simulator rides produced rather stable prediction rates, whereas clinical interviews were not significantly predictive for practical fitness to drive in the MCI patient sample. The selected measures of the previously proposed approach revealed adequate

  6. Driving context influences drivers' decision to engage in visual-manual phone tasks: Evidence from a naturalistic driving study.

    PubMed

    Tivesten, Emma; Dozza, Marco

    2015-06-01

    Visual-manual (VM) phone tasks (i.e., texting, dialing, reading) are associated with an increased crash/near-crash risk. This study investigated how the driving context influences drivers' decisions to engage in VM phone tasks in naturalistic driving. Video-recordings of 1,432 car trips were viewed to identify VM phone tasks and passenger presence. Video, vehicle signals, and map data were used to classify driving context (i.e., curvature, other vehicles) before and during the VM phone tasks (N=374). Vehicle signals (i.e., speed, yaw rate, forward radar) were available for all driving. VM phone tasks were more likely to be initiated while standing still, and less likely while driving at high speeds, or when a passenger was present. Lead vehicle presence did not influence how likely it was that a VM phone task was initiated, but the drivers adjusted their task timing to situations when the lead vehicle was increasing speed, resulting in increasing time headway. The drivers adjusted task timing until after making sharp turns and lane change maneuvers. In contrast to previous driving simulator studies, there was no evidence of drivers reducing speed as a consequence of VM phone task engagement. The results show that experienced drivers use information about current and upcoming driving context to decide when to engage in VM phone tasks. However, drivers may fail to sufficiently increase safety margins to allow time to respond to possible unpredictable events (e.g., lead vehicle braking). Advanced driver assistance systems should facilitate and possibly boost drivers' self-regulating behavior. For instance, they might recognize when appropriate adaptive behavior is missing and advise or alert accordingly. The results from this study could also inspire training programs for novice drivers, or locally classify roads in terms of the risk associated with secondary task engagement while driving. Copyright © 2015. Published by Elsevier Ltd.

  7. The pattern of the electromagnetic field emitted by mobile phones in motor vehicle driving simulators.

    PubMed

    Politański, Piotr; Bortkiewicz, Alicja; Zmyślony, Marek

    2013-06-01

    The paper reports the results of the determinations of UMTS EMF distributions in the driver’s cab of motor vehicle simulators. The results will serve as the basis for future research on the influence of EMF emitted by mobile phones on driver physiology. Two motor vehicle driving simulators were monitored, while an EMF source was placed at the driver's head or on the dashboard of the motor vehicle driving simulator. For every applied configuration, the maximal electric field strength was measured, as were the values at 16 points corresponding to chosen locations on a driver's or passenger's body. When the power was set for the maximum (49 mW), a value of 27 V/m was measured in the vicinity of the driver's head when the phone was close to the head. With the same power, when the phone was placed on the dashboard, the measured maximum was 15.2 V/m in the vicinity of the driver's foot. Similar results were obtained for the passenger. Significant perturbations in EMF distribution and an increase in electric field strength values in the mo-tor vehicle driving simulator were also observed in comparison to free space measurements, and the electric field strength was up to 3 times higher inside the simulator. This study can act as the basis of future studies concerning the influence of the EMF emitted by mobile phones on the physiology of the driver. Additionally, the authors postulate that it is advisable to keep mobile phones at a distance from the head, i.e. use, whenever possible, hands-free kits to reduce EMF exposure, both for drivers and passengers.

  8. Polar Direct Drive--Simulations and Results from OMEGA and the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Radha, P. B.

    2015-11-01

    Polar direct drive (PDD) is a valuable platform to study implosion dynamics at the National Ignition Facility (NIF). While hydrodynamic behavior is expected to scale between OMEGA and the NIF, coronal laser-plasma interactions that influence drive and shell preheat are expected to be different because of the larger coronal density scale lengths characteristic of the NIF. The goal of NIF experiments is to validate physics models (e.g., thermal transport and laser-plasma interactions relevant to energy coupling) at these longer scale lengths to gain confidence in hydrodynamic simulations of direct-drive implosions. Models in the hydrodynamic code DRACO, validated using OMEGA implosions, are used to design and interpret NIF experiments. The physics in these models, including cross-beam energy transfer and nonlocal transport, is discussed. Comparisons with observations including shell and ablation surface trajectory, temporally resolved scattered light and spectra, bang time, shell shape, time-resolved x-ray emission, and areal density are presented from OMEGA and NIF experiments. Excellent agreement is obtained on the backlit shell trajectories and scattered light, providing confidence in the modeling of the laser drive at the longer scale. Possible reasons for the discrepancy in the predicted trajectory of the ablation surface are discussed and planned experiments to address issues such as imprint and shock timing are presented. As will be shown, high-convergence implosions should be possible with custom phase plates relevant to PDD, improved single-beam smoothing, and laser pulse shaping. Such implosions are a necessary step toward a future direct-drive -ignition campaign. A path forward for direct drive on the NIF is presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  9. Effects Of Moderate Sleep Deprivation and Low-Dose Alcohol On Driving Simulator Performance and Perception In Young Men

    PubMed Central

    Vakulin, A.; Baulk, S.D.; Catcheside, P.G.; Anderson, R.; van den Heuvel, C.J.; Banks, S.; McEvoy, R.D.

    2007-01-01

    Study Objectives: To determine the combined effects of sleep restriction and low-dose alcohol on driving simulator performance, EEG, and subjective levels of sleepiness and performance in the mid-afternoon. Design: Repeated measures with 4 experimental conditions. Normal sleep without alcohol, sleep restriction alone (4 hours) and sleep restriction in combination with 2 different low blood alcohol concentrations (0.025 g/dL and 0.035 g/dL). Setting: Sleep Laboratory, Adelaide Institute for Sleep Health. Participants: Twenty-one healthy young men, aged 18–30 years, mean (±SD) = 22.5(±3.7) years, BMI = 25(±6.7) kg/m2; all had normal sleep patterns and were free of sleep disorders. Measurements: Participants completed a 70-minute simulated driving session, commencing at 14:00. Driving parameters included steering deviation, braking reaction time, and number of collisions. Alpha and theta EEG activity and subjective driving performance and sleepiness were also measured throughout the driving task. Results: All measures were significantly affected by time. Steering deviation increased significantly when sleep restriction was combined with the higher dose alcohol. This combination also resulted in a significant increase in alpha/theta EEG activity throughout the drive, as well as greater subjective sleepiness and negative driving performance ratings compared to control or sleep restriction alone. Discussion: These data indicate that combining low-dose alcohol with moderate sleep restriction results in significant decrements to subjective alertness and performance as well as to some driving performance and EEG parameters. This highlights the potential risks of driving after consumption of low and legal doses of alcohol when also sleep restricted. Citation: Vakulin A; Baulk SD; Catcheside PG; Anderson R; van den Heuvel CJ; Banks S; McEvoy RD. Effects of moderate sleep deprivation and low-dose alcohol on driving simulator performance and perception in young men. SLEEP

  10. Adjustable Speed Drive Study, Part 1.

    SciTech Connect

    Wallace, Alan K.; Oregon State University. Dept. of Electrical and Computer Engineering.

    1989-08-01

    Advances in speed control for motors in recent years, notably those in power electronics, have widened the range of application for several adjustable speed drive (ASD) types to include the smaller horsepower sizes. The dc motor drive, formerly in almost universal use for speed control, is being challenged by the high efficiency induction motor/pulse width modulation (PWM) drive; and for special small horsepower size applications, by the permanent magnet motor/PWM inverter drive or by the switched reluctance motor drive. The main characteristics of the several ASD types suitable for small horsepower size applications are discussed, as well as their unwanted side effects: poor power factor, harmonic distortion of the supply, acoustic noise, and electromagnetic interference. A procedure is recommended for determining which, if any, ASD to use. 31 figs., 6 tabs.

  11. Adjustable Speed Drive Study, Part 2.

    SciTech Connect

    Wallace, Alan K.; Oregon State University. Dept. of Electrical and Computer Engineering.

    1989-08-01

    Advances in speed control for motors in recent years, notably those in power electronics, have widened the range of application for several adjustable speed drive (ASD) types to include the smaller horsepower sizes. The DC motor drive, formerly in almost universal use for speed control, is being challenged by the high efficiency induction motor/pulse width modulation (PWM) drive; and for special small horsepower size applications, by the permanent magnet motor/PWM inverter drive or by the switched reluctance motor drive. The main characteristics of the several ASD types suitable for small horsepower size applications are discussed, as well as their unwanted side effects: poor power factor, harmonic distortion of the supply, acoustic noise, and electromagnetic interference. A procedure is recommended for determining which, if any, ASD to use.

  12. Age differences in the takeover of vehicle control and engagement in non-driving-related activities in simulated driving with conditional automation.

    PubMed

    Clark, Hallie; Feng, Jing

    2016-09-26

    High-level vehicle automation has been proposed as a valuable means to enhance the mobility of older drivers, as older drivers experience age-related declines in many cognitive functions that are vital for safe driving. Recent research attempted to examine age differences in how engagement in non-driving-related activities impact driving performance, by instructing drivers to engage in mandatory pre-designed activities. While the mandatory engagement method allows a precise control of the timing and mental workload of the non-driving-related activities, it is different from how a driver would naturally engage in these activities. This study allowed younger (age 18-35, mean age=19.9years) and older drivers (age 62-81, mean age=70.4years) to freely decide when and how to engage in voluntarily chosen non-driving-related activities during simulated driving with conditional automation. We coded video recordings of participants' engagement in non-driving-related activities. We examined the effect of age, level of activity-engagement and takeover notification interval on vehicle control performance during the takeover, by comparing between the high and low engagement groups in younger and older drivers, across two takeover notification interval conditions. We found that both younger and older drivers engaged in various non-driving-related activities during the automated driving portion, with distinct preferences on the type of activity for each age group (i.e., while younger drivers mostly used an electronic device, older drivers tended to converse). There were also significant differences between the two age groups and between the two notification intervals on various driving performance measures. Older drivers benefited more than younger drivers from the longer interval in terms of response time to notifications. Voluntary engagement in non-driving-related activities did not impair takeover performance in general, although there was a trend of older drivers who were

  13. Simple gaze-contingent cues guide eye movements in a realistic driving simulator

    NASA Astrophysics Data System (ADS)

    Pomarjanschi, Laura; Dorr, Michael; Bex, Peter J.; Barth, Erhardt

    2013-03-01

    Looking at the right place at the right time is a critical component of driving skill. Therefore, gaze guidance has the potential to become a valuable driving assistance system. In previous work, we have already shown that complex gaze-contingent stimuli can guide attention and reduce the number of accidents in a simple driving simulator. We here set out to investigate whether cues that are simple enough to be implemented in a real car can also capture gaze during a more realistic driving task in a high-fidelity driving simulator. We used a state-of-the-art, wide-field-of-view driving simulator with an integrated eye tracker. Gaze-contingent warnings were implemented using two arrays of light-emitting diodes horizontally fitted below and above the simulated windshield. Thirteen volunteering subjects drove along predetermined routes in a simulated environment popu­ lated with autonomous traffic. Warnings were triggered during the approach to half of the intersections, cueing either towards the right or to the left. The remaining intersections were not cued, and served as controls. The analysis of the recorded gaze data revealed that the gaze-contingent cues did indeed have a gaze guiding effect, triggering a significant shift in gaze position towards the highlighted direction. This gaze shift was not accompanied by changes in driving behaviour, suggesting that the cues do not interfere with the driving task itself.

  14. Classifying visuomotor workload in a driving simulator using subject specific spatial brain patterns.

    PubMed

    Dijksterhuis, Chris; de Waard, Dick; Brookhuis, Karel A; Mulder, Ben L J M; de Jong, Ritske

    2013-01-01

    A passive Brain Computer Interface (BCI) is a system that responds to the spontaneously produced brain activity of its user and could be used to develop interactive task support. A human-machine system that could benefit from brain-based task support is the driver-car interaction system. To investigate the feasibility of such a system to detect changes in visuomotor workload, 34 drivers were exposed to several levels of driving demand in a driving simulator. Driving demand was manipulated by varying driving speed and by asking the drivers to comply to individually set lane keeping performance targets. Differences in the individual driver's workload levels were classified by applying the Common Spatial Pattern (CSP) and Fisher's linear discriminant analysis to frequency filtered electroencephalogram (EEG) data during an off line classification study. Several frequency ranges, EEG cap configurations, and condition pairs were explored. It was found that classifications were most accurate when based on high frequencies, larger electrode sets, and the frontal electrodes. Depending on these factors, classification accuracies across participants reached about 95% on average. The association between high accuracies and high frequencies suggests that part of the underlying information did not originate directly from neuronal activity. Nonetheless, average classification accuracies up to 75-80% were obtained from the lower EEG ranges that are likely to reflect neuronal activity. For a system designer, this implies that a passive BCI system may use several frequency ranges for workload classifications.

  15. Classifying visuomotor workload in a driving simulator using subject specific spatial brain patterns

    PubMed Central

    Dijksterhuis, Chris; de Waard, Dick; Brookhuis, Karel A.; Mulder, Ben L. J. M.; de Jong, Ritske

    2013-01-01

    A passive Brain Computer Interface (BCI) is a system that responds to the spontaneously produced brain activity of its user and could be used to develop interactive task support. A human-machine system that could benefit from brain-based task support is the driver-car interaction system. To investigate the feasibility of such a system to detect changes in visuomotor workload, 34 drivers were exposed to several levels of driving demand in a driving simulator. Driving demand was manipulated by varying driving speed and by asking the drivers to comply to individually set lane keeping performance targets. Differences in the individual driver's workload levels were classified by applying the Common Spatial Pattern (CSP) and Fisher's linear discriminant analysis to frequency filtered electroencephalogram (EEG) data during an off line classification study. Several frequency ranges, EEG cap configurations, and condition pairs were explored. It was found that classifications were most accurate when based on high frequencies, larger electrode sets, and the frontal electrodes. Depending on these factors, classification accuracies across participants reached about 95% on average. The association between high accuracies and high frequencies suggests that part of the underlying information did not originate directly from neuronal activity. Nonetheless, average classification accuracies up to 75–80% were obtained from the lower EEG ranges that are likely to reflect neuronal activity. For a system designer, this implies that a passive BCI system may use several frequency ranges for workload classifications. PMID:23970851

  16. Functional connectivity analysis using fNIRS in healthy subjects during prolonged simulated driving.

    PubMed

    Xu, Liwei; Wang, Bitian; Xu, Gongcheng; Wang, Wei; Liu, Zhian; Li, Zengyong

    2017-02-15

    Noninvasive and accurate assessment of driving fatigue in relation to brain activity during long-term driving can contribute to traffic safety and accident prevention. This study evaluated functional connectivity (FC) in relevant brain regions. Synergistic mechanisms in different brain regions were detected by a novel simulator, which combined semi-immersive virtual reality technology and functional near-infrared spectroscopy. Each subject was instructed to complete driving tasks coupled with a mental calculation task. Wavelet coherence (WCO) and wavelet phase coherence (WPCO) were calculated and assessed in frequency intervals (I) 0.6-2 and (II) 0.145-0.6Hz as global connectivity measures; (III) 0.052-0.145, (IV) 0.021-0.052, (V) 0.0095-0.021 and (VI) 0.005-0.0095Hz as FC. WCO and WPCO revealed the strength and synchronization of cerebral connectivity, respectively. Significantly low WCO levels were found in intervals I and III in prefrontal cortex (PFC) and IV in motor cortex (MC) at the end of the driving task. Furthermore, significantly low WPCO were found in intervals I, and III in PFC and interval IV in MC. Experimental findings suggested that progressive mental fatigue adversely influences the cognitive function in the PFC and the cooperative mechanism between the PFC and MC.

  17. Effects of chronotype and time of day on the vigilance decrement during simulated driving.

    PubMed

    Correa, Angel; Molina, Enrique; Sanabria, Daniel

    2014-06-01

    The current study tested for the first time the effect of individual differences in circadian rhythmicity (chronotype) on both driving performance and its evolution along time on task. Morning-type and evening-type female participants were tested in morning (8 am) and evening (8 pm) sessions, in which we controlled for prior sleep duration and prior wake. Measures of body temperature, subjective activation and affect, reaction times (RT) in the Psychomotor Vigilance Task (PVT), behavioral performance (error position) and EEG alpha power during simulated driving were collected. The main result showed strong linear increments of mean and standard deviation of error position along time on task (vigilance decrement) when evening-type participants drove at their non-optimal time of day, that is, during the morning session. In contrast, driving performance in the morning-type group remained stable over time on task and was not affected by time of day. This finding can be due to differences in personality traits (e.g., conscientiousness, sensation seeking) and task appraisal associated to extreme chronotypes. The consideration of chronotype in vigilance and driving tasks can enhance safety and human performance by promoting work schedules and countermeasures to prevent failures in the accomplishment of tasks under non-optimal circadian conditions.

  18. Simulation and operation of the EBR-2 automatic control rod drive system

    NASA Astrophysics Data System (ADS)

    Lehto, W. K.; Larson, H. A.; Dean, E. M.; Christensen, L. J.

    An automatic control rod drive system (ACRDS) installed at EBR-II produces shaped power transients from 40% to full reactor power at a linear ramp rate of 4 MWt/s. A digital computer and modified control rod drive provides this capability. Simulation and analysis of ACRDS experiments establish the safety envelope for reactor transient operation. Tailored transients are required as part of USDOE operational reliability testing program for prototypic fast reactor fuel cladding breach behavior studies. After initial EBR-II driver fuel testing and system checkout, test subassemblies were subjected to both slow and fast transients. In addition, the ACRDS is used for steady state operation and will be qualified to control power ascent from initial critical to full power.

  19. The simulations of indirect-drive targets for ignition on megajoule lasers.

    NASA Astrophysics Data System (ADS)

    Lykov, Vladimir; Andreev, Eugene; Ardasheva, Ludmila; Avramenko, Michael; Chernyakov, Valerian; Chizhkov, Maxim; Karlykhanov, Nikalai; Kozmanov, Michael; Lebedev, Serge; Rykovanov, George; Seleznev, Vladimir; Sokolov, Lev; Timakova, Margaret; Shestakov, Alexander; Shushlebin, Aleksander

    2013-10-01

    The calculations were performed with use of radiation hydrodynamic codes developed in RFNC-VNIITF. The analysis of published calculations of indirect-drive targets to obtain ignition on NIF and LMJ lasers has shown that these targets have very low margins for ignition: according to 1D-ERA code calculations it could not be ignited under decreasing of thermonuclear reaction rate less than in 2 times.The purpose of new calculations is search of indirect-drive targets with the raised margins for ignition. The calculations of compression and thermonuclear burning of targets are carried out for conditions of X-ray flux asymmetry obtained in simulations of Rugby hohlraum that were performed with 2D-SINARA code. The requirements to accuracy of manufacturing and irradiation symmetry of targets were studied with use of 2D-TIGR-OMEGA-3T code. The necessity of performed researches is caused by the construction of magajoule laser in Russia.

  20. Suitability of Synthetic Driving Profiles from Traffic Micro-Simulation for Real-World Energy Analysis: Preprint

    SciTech Connect

    Hou, Yunfei; Wood, Eric; Burton, Evan; Gonder, Jeffrey

    2015-10-14

    A shift towards increased levels of driving automation is generally expected to result in improved safety and traffic congestion outcomes. However, little empirical data exists to estimate the impact that automated driving could have on energy consumption and greenhouse gas emissions. In the absence of empirical data on differences between drive cycles from present day vehicles (primarily operated by humans) and future vehicles (partially or fully operated by computers) one approach is to model both situations over identical traffic conditions. Such an exercise requires traffic micro-simulation to not only accurately model vehicle operation under high levels of automation, but also (and potentially more challenging) vehicle operation under present day human drivers. This work seeks to quantify the ability of a commercial traffic micro-simulation program to accurately model real-world drive cycles in vehicles operated primarily by humans in terms of driving speed, acceleration, and simulated fuel economy. Synthetic profiles from models of freeway and arterial facilities near Atlanta, Georgia, are compared to empirical data collected from real-world drivers on the same facilities. Empirical and synthetic drive cycles are then simulated in a powertrain efficiency model to enable comparison on the basis of fuel economy. Synthetic profiles from traffic micro-simulation were found to exhibit low levels of transient behavior relative to the empirical data. Even with these differences, the synthetic and empirical data in this study agree well in terms of driving speed and simulated fuel economy. The differences in transient behavior between simulated and empirical data suggest that larger stochastic contributions in traffic micro-simulation (relative to those present in the traffic micro-simulation tool used in this study) are required to fully capture the arbitrary elements of human driving. Interestingly, the lack of stochastic contributions from models of human drivers

  1. Design and Integration of a Driving Simulator With Eye-Tracking Capabilities in the Computer Assisted Rehabilitation Environment (CAREN)

    DTIC Science & Technology

    2014-07-09

    CAREN Driving Simulation 1 Naval Health Research Center Design and Integration of a Driving Simulator With Eye-Tracking Capabilities in...California 92106-3521 CAREN Driving Simulation 2 INTRODUCTION The Computer Assisted Rehabilitation Environment (CAREN; Motek Medical BV, Amsterdam...activate events, and record information. The ideal driving simulator for NHRC would include a variety of easily modified road courses, and it would

  2. Measuring listening effort: driving simulator vs. simple dual-task paradigm

    PubMed Central

    Wu, Yu-Hsiang; Aksan, Nazan; Rizzo, Matthew; Stangl, Elizabeth; Zhang, Xuyang; Bentler, Ruth

    2014-01-01

    Objectives The dual-task paradigm has been widely used to measure listening effort. The primary objectives of the study were to (1) investigate the effect of hearing aid amplification and a hearing aid directional technology on listening effort measured by a complicated, more real world dual-task paradigm, and (2) compare the results obtained with this paradigm to a simpler laboratory-style dual-task paradigm. Design The listening effort of adults with hearing impairment was measured using two dual-task paradigms, wherein participants performed a speech recognition task simultaneously with either a driving task in a simulator or a visual reaction-time task in a sound-treated booth. The speech materials and road noises for the speech recognition task were recorded in a van traveling on the highway in three hearing aid conditions: unaided, aided with omni directional processing (OMNI), and aided with directional processing (DIR). The change in the driving task or the visual reaction-time task performance across the conditions quantified the change in listening effort. Results Compared to the driving-only condition, driving performance declined significantly with the addition of the speech recognition task. Although the speech recognition score was higher in the OMNI and DIR conditions than in the unaided condition, driving performance was similar across these three conditions, suggesting that listening effort was not affected by amplification and directional processing. Results from the simple dual-task paradigm showed a similar trend: hearing aid technologies improved speech recognition performance, but did not affect performance in the visual reaction-time task (i.e., reduce listening effort). The correlation between listening effort measured using the driving paradigm and the visual reaction-time task paradigm was significant. The finding showing that our older (56 to 85 years old) participants’ better speech recognition performance did not result in reduced

  3. Measuring listening effort: driving simulator versus simple dual-task paradigm.

    PubMed

    Wu, Yu-Hsiang; Aksan, Nazan; Rizzo, Matthew; Stangl, Elizabeth; Zhang, Xuyang; Bentler, Ruth

    2014-01-01

    The dual-task paradigm has been widely used to measure listening effort. The primary objectives of the study were to (1) investigate the effect of hearing aid amplification and a hearing aid directional technology on listening effort measured by a complicated, more real world dual-task paradigm and (2) compare the results obtained with this paradigm to a simpler laboratory-style dual-task paradigm. The listening effort of adults with hearing impairment was measured using two dual-task paradigms, wherein participants performed a speech recognition task simultaneously with either a driving task in a simulator or a visual reaction-time task in a sound-treated booth. The speech materials and road noises for the speech recognition task were recorded in a van traveling on the highway in three hearing aid conditions: unaided, aided with omnidirectional processing (OMNI), and aided with directional processing (DIR). The change in the driving task or the visual reaction-time task performance across the conditions quantified the change in listening effort. Compared to the driving-only condition, driving performance declined significantly with the addition of the speech recognition task. Although the speech recognition score was higher in the OMNI and DIR conditions than in the unaided condition, driving performance was similar across these three conditions, suggesting that listening effort was not affected by amplification and directional processing. Results from the simple dual-task paradigm showed a similar trend: hearing aid technologies improved speech recognition performance, but did not affect performance in the visual reaction-time task (i.e., reduce listening effort). The correlation between listening effort measured using the driving paradigm and the visual reaction-time task paradigm was significant. The finding showing that our older (56 to 85 years old) participants' better speech recognition performance did not result in reduced listening effort was not

  4. The Analysis, Simulation and Control of Cycloconverter Drives for Ship Propulsion.

    DTIC Science & Technology

    1996-12-01

    horsepower applications and with suitable closed loop control can develop torque and speed responses suitable for ship propulsion . External performance...characteristics and control issues for the cycloconverter are discussed, followed by a time domain computer simulation of an integrated ship propulsion drive...designing naval engineer can make educated decisions on the application of a cycloconverter drive for ship propulsion .

  5. Driving monotonous routes in a train simulator: the effect of task demand on driving performance and subjective experience.

    PubMed

    Dunn, Naomi; Williamson, Ann

    2012-01-01

    Although monotony is widely recognised as being detrimental to performance, its occurrence and effects are not yet well understood. This is despite the fact that task-related characteristics, such as monotony and low task demand, have been shown to contribute to performance decrements over time. Participants completed one of two simulated train-driving scenarios. Both were highly monotonous and differed only in terms of the level of cognitive demand required (i.e. low demand or high demand). These results highlight the seriously detrimental effects of the combination of monotony and low task demands and clearly show that even a relatively minor increase in cognitive demand can mitigate adverse monotony-related effects on performance for extended periods of time. Monotony is an inherent characteristic of transport industries, including rail, aviation and road transport, which can have adverse impact on safety, reliability and efficiency. This study highlights possible strategies for mitigating these adverse effects. Practitioner Summary: This study provides evidence for the importance of cognitive demand in mitigating monotony-related effects on performance. The results have clear implications for the rapid onset of performance deterioration in low demand monotonous tasks and demonstrate that these detrimental performance effects can be overcome with simple solutions, such as making the task more cognitively engaging.

  6. Development of a Powered Wheelchair Driving Simulator for Research and Development Use

    NASA Astrophysics Data System (ADS)

    Ito, Takuma; Shino, Motoki; Inoue, Takenobu; Kamata, Minoru

    The purpose of a powered wheelchair driving simulator is to decrease the time and effort in the process of clinic, research and development. In this paper, the design concepts of our driving simulator for research and development use are explained. To design the simulator's software and hardware, two following experiments were conducted. 1: The driver's horizontal field of view was measured. While making a right turn at a corner of a corridor, the movement of the driver's gazing point was measured. From this result, the maximum and minimum values of gazing point movement were analyzed to design the simulator's angle of view. 2: Motion cues such as acceleration and vibration were measured. The characteristics of these motion cues were analyzed to design the motion system. From the experiment results, a driving simulator of a powered wheelchair was developed. To evaluate the driving simulator, the experiment for comparing with a real powered wheelchair driving was conducted. Evaluations improved by the components which were specially designed for the driving simulator.

  7. Detection of braking intention in diverse situations during simulated driving based on EEG feature combination

    NASA Astrophysics Data System (ADS)

    Kim, Il-Hwa; Kim, Jeong-Woo; Haufe, Stefan; Lee, Seong-Whan

    2015-02-01

    Objective. We developed a simulated driving environment for studying neural correlates of emergency braking in diversified driving situations. We further investigated to what extent these neural correlates can be used to detect a participant's braking intention prior to the behavioral response. Approach. We measured electroencephalographic (EEG) and electromyographic signals during simulated driving. Fifteen participants drove a virtual vehicle and were exposed to several kinds of traffic situations in a simulator system, while EEG signals were measured. After that, we extracted characteristic features to categorize whether the driver intended to brake or not. Main results. Our system shows excellent detection performance in a broad range of possible emergency situations. In particular, we were able to distinguish three different kinds of emergency situations (sudden stop of a preceding vehicle, sudden cutting-in of a vehicle from the side and unexpected appearance of a pedestrian) from non-emergency (soft) braking situations, as well as from situations in which no braking was required, but the sensory stimulation was similar to stimulations inducing an emergency situation (e.g., the sudden stop of a vehicle on a neighboring lane). Significance. We proposed a novel feature combination comprising movement-related potentials such as the readiness potential, event-related desynchronization features besides the event-related potentials (ERP) features used in a previous study. The performance of predicting braking intention based on our proposed feature combination was superior compared to using only ERP features. Our study suggests that emergency situations are characterized by specific neural patterns of sensory perception and processing, as well as motor preparation and execution, which can be utilized by neurotechnology based braking assistance systems.

  8. Using alcohol intoxication goggles (Fatal Vision® goggles) to detect alcohol related impairment in simulated driving.

    PubMed

    McCartney, Danielle; Desbrow, Ben; Irwin, Christopher

    2017-01-02

    Fatal vision goggles (FVGs) are image-distorting equipment used within driver education programs to simulate alcohol-related impairment. However, there is no empirical evidence comparing the behavioral effects associated with wearing FVGs to alcohol intoxication. The purpose of this study was to determine the validity of FVGs in producing alcohol-related impairment in simulated driving. Twenty-two healthy males (age: 23 ± 3 years, mean ± SD) participated in a placebo-controlled crossover design study involving 4 experimental trials. In each trial, participants completed a baseline level simulated driving task followed by an experimental driving task, involving one of 4 treatments: (1) a dose of alcohol designed to elicit 0.080% breath alcohol concentration (BrAC; AB), (2) an alcohol placebo beverage (PB), (3) FVG (estimated % blood alcohol concentration [BAC] 0.070-0.100+), and (4) placebo goggles (PGs). The driving tasks included 3 separate scenarios lasting ∼5 min each; these were a simple driving scenario, a complex driving scenario, and a hazard perception driving scenario. Selected lateral control parameters (standard deviation of lane position [SDLP]; total number of lane crossings [LCs]) and longitudinal control parameters (average speed; standard deviation of speed [SDSP]; distance headway; minimum distance headway) were monitored during the simple and complex driving scenarios. Latency to 2 different stimuli (choice reaction time [CRT]) was tested in the hazard perception driving scenario. Subjective ratings of mood and attitudes toward driving were also provided during each of the trials. Neither placebo treatment influenced simulated driving performance. Mean BrAC was 0.060 ± 0.010% at the time of driving on the AB trial. Lateral control: In the simple driving scenario, SDLP and LC were not affected under any of the experimental treatments. However, in the complex driving scenario, significantly greater SDLP was observed on both the FVG and AB

  9. The effects of simulated fog and motion on simulator sickness in a driving simulator and the duration of after-effects.

    PubMed

    Dziuda, Lukasz; Biernacki, Marcin P; Baran, Paulina M; Truszczyński, Olaf E

    2014-05-01

    In the study, we checked: 1) how the simulator test conditions affect the severity of simulator sickness symptoms; 2) how the severity of simulator sickness symptoms changes over time; and 3) whether the conditions of the simulator test affect the severity of these symptoms in different ways, depending on the time that has elapsed since the performance of the task in the simulator. We studied 12 men aged 24-33 years (M = 28.8, SD = 3.26) using a truck simulator. The SSQ questionnaire was used to assess the severity of the symptoms of simulator sickness. Each of the subjects performed three 30-minute tasks running along the same route in a driving simulator. Each of these tasks was carried out in a different simulator configuration: A) fixed base platform with poor visibility; B) fixed base platform with good visibility; and C) motion base platform with good visibility. The measurement of the severity of the simulator sickness symptoms took place in five consecutive intervals. The results of the analysis showed that the simulator test conditions affect in different ways the severity of the simulator sickness symptoms, depending on the time which has elapsed since performing the task on the simulator. The simulator sickness symptoms persisted at the highest level for the test conditions involving the motion base platform. Also, when performing the tasks on the motion base platform, the severity of the simulator sickness symptoms varied depending on the time that had elapsed since performing the task. Specifically, the addition of motion to the simulation increased the oculomotor and disorientation symptoms reported as well as the duration of the after-effects. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  10. Useful field of view in simulated driving: Reaction times and eye movements of drivers

    PubMed Central

    Seya, Yasuhiro; Nakayasu, Hidetoshi; Yagi, Tadasu

    2013-01-01

    To examine the spatial distribution of a useful field of view (UFOV) in driving, reaction times (RTs) and eye movements were measured in simulated driving. In the experiment, a normal or mirror-reversed letter “E” was presented on driving images with different eccentricities and directions from the current gaze position. The results showed significantly slower RTs in the upper and upper left directions than in the other directions. The RTs were significantly slower in the left directions than in the right directions. These results suggest that the UFOV in driving may be asymmetrical among the meridians in the visual field. PMID:24349688

  11. Predicting drowsy driving in real-time situations: Using an advanced driving simulator, accelerated failure time model, and virtual location-based services.

    PubMed

    Wang, Junhua; Sun, Shuaiyi; Fang, Shouen; Fu, Ting; Stipancic, Joshua

    2017-02-01

    This paper aims to both identify the factors affecting driver drowsiness and to develop a real-time drowsy driving probability model based on virtual Location-Based Services (LBS) data obtained using a driving simulator. A driving simulation experiment was designed and conducted using 32 participant drivers. Collected data included the continuous driving time before detection of drowsiness and virtual LBS data related to temperature, time of day, lane width, average travel speed, driving time in heavy traffic, and driving time on different roadway types. Demographic information, such as nap habit, age, gender, and driving experience was also collected through questionnaires distributed to the participants. An Accelerated Failure Time (AFT) model was developed to estimate the driving time before detection of drowsiness. The results of the AFT model showed driving time before drowsiness was longer during the day than at night, and was longer at lower temperatures. Additionally, drivers who identified as having a nap habit were more vulnerable to drowsiness. Generally, higher average travel speeds were correlated to a higher risk of drowsy driving, as were longer periods of low-speed driving in traffic jam conditions. Considering different road types, drivers felt drowsy more quickly on freeways compared to other facilities. The proposed model provides a better understanding of how driver drowsiness is influenced by different environmental and demographic factors. The model can be used to provide real-time data for the LBS-based drowsy driving warning system, improving past methods based only on a fixed driving.

  12. Control Design for a Motion Cueing on Driving Simulator

    NASA Astrophysics Data System (ADS)

    de-J. Lozoya-Santos, Jorge; Tudon-Martinez, Juan C.; Salinas, Julio

    2017-01-01

    A Linear Quadratic Regulator (LQR) has been designed to simulate the pitch and roll vehicle dynamics of a platform which is connected to the real time simulation environment of Dynacar. The motion cueing algorithm translates the movement of the simulated vehicle to the platform using three rotary actuators, by satisfying all actuation boundaries. Experimental results illustrate that the LQR motion cueing algorithm performs satisfactory the tracking control at low frequencies, close to the resonance frequencies of the pitch and roll motion.

  13. Analyzing driver-pedestrian interaction in a mixed-street environment using a driving simulator.

    PubMed

    Obeid, Hassan; Abkarian, Hoseb; Abou-Zeid, Maya; Kaysi, Isam

    2017-08-25

    This paper presents the design, analysis and results of a driving simulator experiment conducted to study the interaction between drivers and pedestrians in a mixed-street environment. Ninety-six students of the American University of Beirut (AUB) participated in the experiment that took place in the Transportation and Infrastructure Laboratory of AUB. The study looked at the driver-pedestrian interaction from the driver's perspective, by quantifying the effects of different scenario variables on the driving behavior of the participants. Kruskall-Wallis test shows that drivers' behavior in proximity of pedestrians tends to be statistically significantly less aggressive when their approach velocity is lower, curb-side parking is not allowed, a crosswalk exists, and the number of pedestrians crossing the street is higher. A discrete choice model for the yielding behavior of the drivers was also developed as a function of different predictor variables. Five out of the six predictors considered (except for gender) had a statistically significant effect on the yielding behavior, particularly the effects of curb-side parking, number of pedestrians crossing, and approach velocity. The model was then used to evaluate the effect of policy variables on the yielding probabilities of the drivers. The results of this study enrich current knowledge and understanding of drivers' behavior and their interaction with pedestrians, especially with studying the effects of scenario variables that were not addressed before; this would help planners propose and evaluate safety measures and traffic calming techniques to reduce the risks on pedestrians. The study also confirms the effectiveness of driving simulators in studying driver-pedestrian interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effects of mood induction via music on cardiovascular measures of negative emotion during simulated driving.

    PubMed

    Fairclough, Stephen H; van der Zwaag, Marjolein; Spiridon, Elena; Westerink, Joyce

    2014-04-22

    A study was conducted to investigate the potential of mood induction via music to influence cardiovascular correlates of negative emotions experience during driving behaviour. One hundred participants were randomly assigned to one of five groups, four of whom experienced different categories of music: High activation/positive valence (HA/PV), high activation/negative valence (HA/NV), low activation/positive valence (LA/PV) and low activation/negative valence (LA/NV). Following exposure to their respective categories of music, participants were required to complete a simulated driving journey with a fixed time schedule. Negative emotion was induced via exposure to stationary traffic during the simulated route. Cardiovascular reactivity was measured via blood pressure, heart rate and cardiovascular impedance. Subjective self-assessment of anger and mood was also recorded. Results indicated that low activation music, regardless of valence, reduced systolic reactivity during the simulated journey relative to HA/NV music and the control (no music) condition. Self-reported data indicated that participants were not consciously aware of any influence of music on their subjective mood. It is concluded that cardiovascular reactivity to negative mood may be mediated by the emotional properties of music.

  15. Simulation of three-phase induction motor drives using indirect field oriented control in PSIM environment

    NASA Astrophysics Data System (ADS)

    Aziri, Hasif; Patakor, Fizatul Aini; Sulaiman, Marizan; Salleh, Zulhisyam

    2017-09-01

    This paper presents the simulation of three-phase induction motor drives using Indirect Field Oriented Control (IFOC) in PSIM environment. The asynchronous machine is well known about natural limitations fact of highly nonlinearity and complexity of motor model. In order to resolve these problems, the IFOC is applied to control the instantaneous electrical quantities such as torque and flux component. As FOC is controlling the stator current that represented by a vector, the torque component is aligned with d coordinate while the flux component is aligned with q coordinate. There are five levels of the incremental system are gradually built up to verify and testing the software module in the system. Indeed, all of system build levels are verified and successfully tested in PSIM environment. Moreover, the corresponding system of five build levels are simulated in PSIM environment which is user-friendly for simulation studies in order to explore the performance of speed responses based on IFOC algorithm for three-phase induction motor drives.

  16. Modeling Driving Performance Using In-Vehicle Speech Data From a Naturalistic Driving Study.

    PubMed

    Kuo, Jonny; Charlton, Judith L; Koppel, Sjaan; Rudin-Brown, Christina M; Cross, Suzanne

    2016-09-01

    We aimed to (a) describe the development and application of an automated approach for processing in-vehicle speech data from a naturalistic driving study (NDS), (b) examine the influence of child passenger presence on driving performance, and (c) model this relationship using in-vehicle speech data. Parent drivers frequently engage in child-related secondary behaviors, but the impact on driving performance is unknown. Applying automated speech-processing techniques to NDS audio data would facilitate the analysis of in-vehicle driver-child interactions and their influence on driving performance. Speech activity detection and speaker diarization algorithms were applied to audio data from a Melbourne-based NDS involving 42 families. Multilevel models were developed to evaluate the effect of speech activity and the presence of child passengers on driving performance. Speech activity was significantly associated with velocity and steering angle variability. Child passenger presence alone was not associated with changes in driving performance. However, speech activity in the presence of two child passengers was associated with the most variability in driving performance. The effects of in-vehicle speech on driving performance in the presence of child passengers appear to be heterogeneous, and multiple factors may need to be considered in evaluating their impact. This goal can potentially be achieved within large-scale NDS through the automated processing of observational data, including speech. Speech-processing algorithms enable new perspectives on driving performance to be gained from existing NDS data, and variables that were once labor-intensive to process can be readily utilized in future research. © 2016, Human Factors and Ergonomics Society.

  17. A Microcomputer-Based Control And Simulation Of An Advanced Ipm Synchronous Machine Drive System For Electric Vehicle Propulsion

    NASA Astrophysics Data System (ADS)

    Bose, B. K.; Szczesny, P. M.

    1987-10-01

    Advanced digital control and computer-aided control system design techniques are playing key roles in the complex drive system design and control implementation. The paper describes a high performance microcomputer-based control and digital simulation of an inverter-fed interior permanent magnet (IPM) synchronous machine which uses Neodymium-Iron-Boron magnet. The fully operational four-quadrant drive system includes constant-torque region with zero speed operation and high speed field-weakening constant-power region. The control uses vector or field-oriented technique in constant-torque region with the direct axis aligned to the stator flux, whereas the constant-power region control is based on torque angle orientation of the impressed square-wave voltage. All the key feedback signals for the control are estimated with precision. The drive system is basically designed with an outer torque control loop for electric vehicle application, but speed and position control loops can be added for other industrial applications. The distributed microcomputer-based control system is based on Intel-8096 microcontroller and Texas Instruments TMS32010 type digital signal processor. The complete drive system has been simulated using the VAX-based simulation language SIMNON* to verify the feasibility of the control laws and to study the performances of the drive system. The simulation results are found to have excellent correlation with the laboratory breadboard tests.

  18. Positive correlation between drowsiness and prefrontal activation during a simulated speed-control driving task.

    PubMed

    Liu, Tao

    2014-11-12

    The present study aimed to examine the relationship between drowsiness and prefrontal activation during simulated driving tasks using a wireless portable near-infrared spectroscopy device. Participants drove from start to goal along default routes with either intentional control of their driving speed (speed-control group) or not (speed-free group). Drowsiness level was assessed using a five-item Likert-type questionnaire. The behavioral data indicated longer driving time in the speed-control group than in the speed-free group, whereas no difference in the number of errors was found between the two groups. Importantly, the speed-control group showed a significant positive correlation between the drowsiness score and left prefrontal activation, whereas the speed-free group did not. The results suggest that drowsy individuals may show increased prefrontal activation as compensatory efforts to maintain the desired level of performance in tasks that require deliberate control of behaviors. Furthermore, the present study shows that near-infrared spectroscopy may provide us with a possibility to examine the state of drowsiness during daily-life operations.

  19. Deficits in Attention and Visual Processing but not Global Cognition Predict Simulated Driving Errors in Drivers Diagnosed With Mild Alzheimer's Disease.

    PubMed

    Yamin, Stephanie; Stinchcombe, Arne; Gagnon, Sylvain

    2016-06-01

    This study sought to predict driving performance of drivers with Alzheimer's disease (AD) using measures of attention, visual processing, and global cognition. Simulated driving performance of individuals with mild AD (n = 20) was contrasted with performance of a group of healthy controls (n = 21). Performance on measures of global cognitive function and specific tests of attention and visual processing were examined in relation to simulated driving performance. Strong associations were observed between measures of attention, notably the Test of Everyday Attention (sustained attention; r = -.651, P = .002) and the Useful Field of View (r = .563, P = .010), and driving performance among drivers with mild AD. The Visual Object and Space Perception Test-object was significantly correlated with the occurrence of crashes (r = .652, P = .002). Tests of global cognition did not correlate with simulated driving outcomes. The results suggest that professionals exercise caution when extrapolating driving performance based on global cognitive indicators. © The Author(s) 2015.

  20. Simulation of Driving in Low-Visibility Conditions: Does Stereopsis Improve Speed Perception?

    PubMed

    Brooks, Kevin R; Rafat, Mohammed E

    2015-02-01

    Laboratory-based studies of perceived speed show that, under most circumstances, perceived speed is reduced as a function of contrast. However, a recent investigation of perceived vehicular speed while driving around a closed road circuit showed no such effect (Owens, Wood, & Carberry, 2010, Perception, 39: , 1199-1215). We sought to probe the source of this discrepancy, asking whether the presence or absence of stereoscopic motion information might account for the difference in results. In a two-alternative forced-choice psychophysical speed-discrimination task, observers compared the speed of high- and low-contrast driving clips filmed with a 3-D camera and presented either stereoscopically (3-D) or monoscopically (2-D). Although perceived speed was reduced at low contrast, the size of this misperception was equivalent for 2-D and 3-D presentations. However, the inclusion of stereoscopic cues to vehicular speed caused significant improvements in the precision of speed judgments. It is concluded that although stereopsis can provide access to valuable information on perceived speed, contrast-independent speed estimation as demonstrated by Owens et al. (2010) is more likely to reflect the use of the full visual field in a real driving situation (compared with limited field of view simulations), or the additional contributions of nonvisual cues rather than stereopsis.

  1. Potential benefits and costs of concurrent task engagement to maintain vigilance: a driving simulator investigation.

    PubMed

    Atchley, Paul; Chan, Mark

    2011-02-01

    The objective of this study was to investigate the nature of concurrent task interference during a vigilance task and to determine whether a concurrent task improves performance with decreased vigilance. Research has repeatedly shown that engaging in a cell phone conversation while driving increases the risk of getting into crashes. At the same time, it has also been found that task monotony could lead to an increase in crash risk. There is evidence that suggests that engaging in a concurrent task reduces the effects of monotony, leading to an improvement in vigilance task performance. A monotonous drive in a driving simulator was used to investigate the effects of a concurrent verbal task. Three task conditions were used: no verbal task, continuous verbal task, and late verbal task. When engaged in a secondary verbal task, drivers showed improved lane-keeping performance and steering control when vigilance was lowest. A strategically placed concurrent task can improve performance when vigilance is at its lowest. There is potential for the design of a countermeasure system that can be strategically activated by an automated system monitoring driver performance.

  2. Situation awareness and driving performance in a simulated navigation task.

    PubMed

    Ma, R; Kaber, D B

    2007-08-01

    The objective of this study was to identify task and vehicle factors that may affect driver situation awareness (SA) and its relationship to performance, particularly in strategic (navigation) tasks. An experiment was conducted to assess the effects of in-vehicle navigation aids and reliability on driver SA and performance in a simulated navigation task. A total of 20 participants drove a virtual car and navigated a large virtual suburb. They were required to follow traffic signs and navigation directions from either a human aid via a mobile phone or an automated aid presented on a laptop. The navigation aids operated under three different levels of information reliability (100%, 80% and 60%). A control condition was used in which each aid presented a telemarketing survey and participants navigated using a map. Results revealed perfect navigation information generally improved driver SA and performance compared to unreliable navigation information and the control condition (task-irrelevant information). In-vehicle automation appears to mediate the relationship of driver SA to performance in terms of operational and strategic (navigation) behaviours. The findings of this work support consideration of driver SA in the design of future vehicle automation for navigation tasks.

  3. VTI Driving Simulator: Mathematical Model of a Four-wheeled Vehicle for Simulation in Real Time. VTI Rapport 267A.

    ERIC Educational Resources Information Center

    Nordmark, Staffan

    1984-01-01

    This report contains a theoretical model for describing the motion of a passenger car. The simulation program based on this model is used in conjunction with an advanced driving simulator and run in real time. The mathematical model is complete in the sense that the dynamics of the engine, transmission and steering system is described in some…

  4. VTI Driving Simulator: Mathematical Model of a Four-wheeled Vehicle for Simulation in Real Time. VTI Rapport 267A.

    ERIC Educational Resources Information Center

    Nordmark, Staffan

    1984-01-01

    This report contains a theoretical model for describing the motion of a passenger car. The simulation program based on this model is used in conjunction with an advanced driving simulator and run in real time. The mathematical model is complete in the sense that the dynamics of the engine, transmission and steering system is described in some…

  5. Enhancing Entropy and Enthalpy Fluctuations to Drive Crystallization in Atomistic Simulations.

    PubMed

    Piaggi, Pablo M; Valsson, Omar; Parrinello, Michele

    2017-07-07

    Crystallization is a process of great practical relevance in which rare but crucial fluctuations lead to the formation of a solid phase starting from the liquid. As in all first order first transitions, there is an interplay between enthalpy and entropy. Based on this idea, in order to drive crystallization in molecular simulations, we introduce two collective variables, one enthalpic and the other entropic. Defined in this way, these collective variables do not prejudge the structure into which the system is going to crystallize. We show the usefulness of this approach by studying the cases of sodium and aluminum that crystallize in the bcc and fcc crystalline structures, respectively. Using these two generic collective variables, we perform variationally enhanced sampling and well tempered metadynamics simulations and find that the systems transform spontaneously and reversibly between the liquid and the solid phases.

  6. Enhancing Entropy and Enthalpy Fluctuations to Drive Crystallization in Atomistic Simulations

    NASA Astrophysics Data System (ADS)

    Piaggi, Pablo M.; Valsson, Omar; Parrinello, Michele

    2017-07-01

    Crystallization is a process of great practical relevance in which rare but crucial fluctuations lead to the formation of a solid phase starting from the liquid. As in all first order first transitions, there is an interplay between enthalpy and entropy. Based on this idea, in order to drive crystallization in molecular simulations, we introduce two collective variables, one enthalpic and the other entropic. Defined in this way, these collective variables do not prejudge the structure into which the system is going to crystallize. We show the usefulness of this approach by studying the cases of sodium and aluminum that crystallize in the bcc and fcc crystalline structures, respectively. Using these two generic collective variables, we perform variationally enhanced sampling and well tempered metadynamics simulations and find that the systems transform spontaneously and reversibly between the liquid and the solid phases.

  7. Driving functions in a video simulator in chronic non-malignant pain patients using and not using codeine.

    PubMed

    Nilsen, Halvard K; Landrø, Nils I; Kaasa, Stein; Jenssen, Gunnar D; Fayers, Peter; Borchgrevink, Petter C

    2011-04-01

    A considerable number of Europeans suffer from chronic pain and are using opioids, particularly of the weak type. It is a clinical impression that many of these are driving or wish to drive a car. The aims of this study were to investigate if codeine influences driving ability in a simulator, and to examine if chronic pain per se might impair such functions. Twenty patients with chronic pain on long-term codeine therapy were compared to 20 chronic pain patients not using codeine in a video driving simulator test. The chronic pain patients were then compared to 20 healthy controls. The primary outcome measures were reaction time and number of missed reactions. The patients using codeine 120-270 mg (mean 180 mg) daily showed the same driving skills as patients not using codeine, and the codeine level did not affect the results. This was the case both 1h after intake of a single dose of 60 mg codeine and five or more hours after the last codeine intake. The reaction times were significantly slower for the chronic pain patients, in both rural and urban driving conditions, compared to the healthy controls (difference 0.11s. and 0.12s., respectively). The chronic pain patients missed almost twice as many reactions to traffic signs. There were no difference between the groups in steering precision. The main finding in this simulator study was that codeine does not impair driving-related abilities over and above what is associated with chronic pain per se. Copyright © 2010 European Federation of International Association for the Study of Pain Chapters. Published by Elsevier Ltd. All rights reserved.

  8. A study on the relationship between personality and driving styles.

    PubMed

    Poó, Fernando Martín; Ledesma, Ruben Daniel

    2013-01-01

    Research on driving behavior and personality traits is a key factor in the development of driver-oriented safety interventions. However, research is fragmented and a multidimensional perspective is lacking. The primary aim of this study is to assess the multiple relationships between driving styles and personality traits using the alternative 5-factor model. A secondary goal is to determine whether these relationships vary by gender and age. Data were collected from a sample of 908 Argentine drivers. Driving styles were assessed using the Multidimensional Driving Style Inventory. Personality was assessed with the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ-50-CC; Aluja et al. 2006) questionnaire. Different patterns of personality are associated with different driving styles. These relationships appear to be robust with respect to gender and age; however, in some cases these variables did influence the observed relationships. The results provide researchers with a more comprehensive understanding of the relationships between personality traits and driving styles. Practical prevention measures are discussed.

  9. Active and Passive Fatigue in Simulated Driving: Discriminating Styles of Workload Regulation and Their Safety Impacts

    PubMed Central

    Saxby, Dyani J.; Matthews, Gerald; Warm, Joel S.; Hitchcock, Edward M.; Neubauer, Catherine

    2015-01-01

    Despite the known dangers of driver fatigue, it is a difficult construct to study empirically. Different forms of task-induced fatigue may differ in their effects on driver performance and safety. Desmond and Hancock (2001) defined active and passive fatigue states that reflect different styles of workload regulation. In 2 driving simulator studies we investigated the multidimensional subjective states and safety outcomes associated with active and passive fatigue. Wind gusts were used to induce active fatigue, and full vehicle automation to induce passive fatigue. Drive duration was independently manipulated to track the development of fatigue states over time. Participants were undergraduate students. Study 1 (N = 108) focused on subjective response and associated cognitive stress processes, while Study 2 (N = 168) tested fatigue effects on vehicle control and alertness. In both studies the 2 fatigue manipulations produced different patterns of subjective response reflecting different styles of workload regulation, appraisal, and coping. Active fatigue was associated with distress, overload, and heightened coping efforts, whereas passive fatigue corresponded to large-magnitude declines in task engagement, cognitive underload, and reduced challenge appraisal. Study 2 showed that only passive fatigue reduced alertness, operationalized as speed of braking and steering responses to an emergency event. Passive fatigue also increased crash probability, but did not affect a measure of vehicle control. Findings support theories that see fatigue as an outcome of strategies for managing workload. The distinction between active and passive fatigue is important for assessment of fatigue and for evaluating automated driving systems which may induce dangerous levels of passive fatigue. PMID:24041288

  10. Experimental Effects of Injunctive Norms on Simulated Risky Driving Among Teenage Males

    PubMed Central

    Simons-Morton, Bruce G.; Pradhan, Anuj K.; Bingham, C. Raymond; Falk, Emily B.; Li, Kaigang; Ouimet, Marie Claude; Almani, Farideh; Shope, Jean T.

    2014-01-01

    Objective Teenage passengers affect teenage driving performance, possibly by social influence. To examine the effect of social norms on driving behavior, male teenagers were randomly assigned to drive in a simulator with a peer-aged confederate to whom participants were primed to attribute either risk-accepting or risk-averse social norms. It was hypothesized that teenage drivers would engage in more risky driving behavior in the presence of peer passengers than no passengers, and with a risk-accepting compared with a risk-averse passenger. Method 66 male participants aged 16 to18 years holding a provisional driver license were randomized to drive with a risk-accepting or risk-averse passenger in a simulator. Failure to Stop at a red light and percent Time in Red (light) were measured as primary risk-relevant outcomes of interest at 18 intersections, while driving once alone and once with their assigned passenger. Results The effect of passenger presence on risky driving was moderated by passenger type for Failed to Stop in a generalized linear mixed model (OR = 1.84, 95% CI [1.19, 2.86], p < .001), and percent Time in Red in a mixed model (B = 7.71, 95% CI [1.54, 13.87], p < .05). Conclusions Exposure of teenage males to a risk-accepting confederate peer increased teenage males’ risky simulated driving behavior compared with exposure to a risk-averse confederate peer. These results indicate that variability in teenage risky driving could be partially explained by social norms. PMID:24467258

  11. X-Point Reconnection from Shear Driving in Kinetic Simulations

    NASA Astrophysics Data System (ADS)

    Black, C.; Antiochos, S. K.; DeVore, C. R.; Germaschewski, K.; Bessho, N.; Karpen, J. T.

    2014-12-01

    The explosive energy release in solar eruptive phenomena such as CMEs/eruptive flares and coronal jets is believed to be due to magnetic reconnection. Magnetic free energy builds up slowly in the corona due to footpoint stressing by the photospheric motions. Along with the free energy, current sheets build up at coronal nulls, which eventually triggers fast reconnection and explosive energy release. This basic scenario has been modeled extensively by MHD simulations and applied to both CMEs/eruptive flares and jets, but the reconnection itself is well-known to be due to kinetic processes. Consequently, it is imperative that shear-driven X-point reconnection be modeled in a fully kinetic system so as to test and guide the MHD results. In MHD simulations, the application of a magnetic-field shear at the system boundary is a trivial matter, but this is definitely not the case for a kinetic system, because the electric currents need to be fully consistent with all the mass motions. We present the first results of reconnection in a 2D X-Point geometry due to a velocity shear driver perpendicular to the plane of reconnection. We compare the results to high-resolution MHD simulations and discuss the implications for coronal activity.

  12. Molecular dynamics simulations of grain boundary migration during recrystallization employing tilt and twist dislocation boundaries to provide the driving pressure

    NASA Astrophysics Data System (ADS)

    Godiksen, R. B. N.; Schmidt, S.; Jensen, D. Juul

    2008-09-01

    Molecular dynamics simulations of grain boundary migration, where the driving pressure P is the excess stored energy due to dislocation structures, have been performed. This represents recrystallization in metals. Two types of dislocation structures have been simulated: (a) tilt dislocation boundaries, where edge dislocations are arranged as parallel arrays, (b) twist dislocation boundaries, where screw dislocations are arranged in interconnected dislocation networks. The velocity v and mobility M of the migrating grain boundaries have been calculated from the simulations. v and M are higher in twist-type simulations than in tilt-type simulations, although the activation energies are similar in the two cases. v ~ P is observed for tilt simulations where the driving pressure is changed by varying the density of dislocation boundaries and for twist simulations where the driving pressure is changed by varying the misorientation across dislocation boundaries. When the misorientations across edge dislocation boundaries are varied, however, the simulations show v ~ P2. It is suggested that this deviation from the usual v ~ P-relationship is due to local interactions between the grain boundary and nearby individual dislocations. Misorientation variations across grain boundaries have also been simulated, but the mobilities show little dependence on this. The present simulations result in mobilities and activation energies that are, respectively, significantly higher and somewhat lower than experimental values. A direct mimic of experimental observations is, however not the purpose of this study. Rather the present simulations are based on idealized dislocation structures and suggest that variations in the dislocation structures may play a dominant role in recrystallization dynamics and that local effects are very important phenomena, essential for the interpretation of recrystallization mechanisms.

  13. A demonstration of motion base design alternatives for the National Advanced Driving Simulator

    NASA Technical Reports Server (NTRS)

    Mccauley, Michael E.; Sharkey, Thomas J.; Sinacori, John B.; Laforce, Soren; Miller, James C.; Cook, Anthony

    1992-01-01

    A demonstration of the capability of NASA's Vertical Motion Simulator to simulate two alternative motion base designs for the National Advanced Driving simulator (NADS) is reported. The VMS is located at ARC. The motion base conditions used in this demonstration were as follows: (1) a large translational motion base; and (2) a motion base design with limited translational capability. The latter had translational capability representative of a typical synergistic motion platform. These alternatives were selected to test the prediction that large amplitude translational motion would result in a lower incidence or severity of simulator induced sickness (SIS) than would a limited translational motion base. A total of 10 drivers performed two tasks, slaloms and quick-stops, using each of the motion bases. Physiological, objective, and subjective measures were collected. No reliable differences in SIS between the motion base conditions was found in this demonstration. However, in light of the cost considerations and engineering challenges associated with implementing a large translation motion base, performance of a formal study is recommended.

  14. Speech Auditory Alerts Promote Memory for Alerted Events in a Video-Simulated Self-Driving Car Ride.

    PubMed

    Nees, Michael A; Helbein, Benji; Porter, Anna

    2016-05-01

    Auditory displays could be essential to helping drivers maintain situation awareness in autonomous vehicles, but to date, few or no studies have examined the effectiveness of different types of auditory displays for this application scenario. Recent advances in the development of autonomous vehicles (i.e., self-driving cars) have suggested that widespread automation of driving may be tenable in the near future. Drivers may be required to monitor the status of automation programs and vehicle conditions as they engage in secondary leisure or work tasks (entertainment, communication, etc.) in autonomous vehicles. An experiment compared memory for alerted events-a component of Level 1 situation awareness-using speech alerts, auditory icons, and a visual control condition during a video-simulated self-driving car ride with a visual secondary task. The alerts gave information about the vehicle's operating status and the driving scenario. Speech alerts resulted in better memory for alerted events. Both auditory display types resulted in less perceived effort devoted toward the study tasks but also greater perceived annoyance with the alerts. Speech auditory displays promoted Level 1 situation awareness during a simulation of a ride in a self-driving vehicle under routine conditions, but annoyance remains a concern with auditory displays. Speech auditory displays showed promise as a means of increasing Level 1 situation awareness of routine scenarios during an autonomous vehicle ride with an unrelated secondary task. © 2016, Human Factors and Ergonomics Society.

  15. Lower Hybrid Current Drive Experiments on Alcator C-Mod: Comparison with Theory and Simulation

    NASA Astrophysics Data System (ADS)

    Bonoli, Paul

    2007-11-01

    Recently, lower hybrid current drive (LHCD) experiments have been carried out on Alcator C-Mod using an RF system consisting of 12 klystrons at 4.6 GHz, feeding a 4 x 22 waveguide array. Up to 900 kW of LH power has been coupled in the range1.6 <= n//<= 4), where n// is the parallel refractive index. Driven LH currents have been inferred from magnetic measurements by extrapolating to zero loop voltage, yielding an efficiency of n20ILHR/PLH 0.3 [1]. We have simulated the LH current drive in these discharges using the combined ray tracing / 3D (r, v, v//) Fokker Planck code GENRAY -- CQL3D [2] and found similar current drive efficiencies. Measurements of nonthermal x-ray emission and electron cyclotron emission (ECE) confirm the presence of a significant fast electron population that varies with waveguide phasing and plasma density. Studies are currently underway to investigate the role of fast electron diffusion and full-wave effects such as diffractional broadening in determining the spatial and velocity space structure of the nonthermal electrons. The 3D (r, v, v//) electron distribution function from CQL3D has been used in synthetic diagnostic codes to simulate the measured hard x-ray and ECE emissions. Fast electron diffusion times have been inferred from x-ray data by employing a radial diffusion operator in CQL3D and determining the fast electron diffusivities that are required to reproduce the experimentally observed profiles of hard x-ray emission. Finally, we have been performing full-wave LH field simulations using the massively parallel TORIC --LH solver [3] in order to assess spatial and spectral broadening of the incident wave front that can result from diffraction and wave focusing effects. [1] R. Parker, Bull. Am. Phys. Soc. 51, 20 (2006). [2] R.W. Harvey and M. McCoy, ``The CQL3D Fokker Planck Code,'' Proc. IAEA Tech. Comm. Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992. [3] J. C. Wright et al., Nucl. Fusion 45

  16. Assessment of wheelchair driving performance in a virtual reality-based simulator

    PubMed Central

    Mahajan, Harshal P.; Dicianno, Brad E.; Cooper, Rory A.; Ding, Dan

    2013-01-01

    Objective To develop a virtual reality (VR)-based simulator that can assist clinicians in performing standardized wheelchair driving assessments. Design A completely within-subjects repeated measures design. Methods Participants drove their wheelchairs along a virtual driving circuit modeled after the Power Mobility Road Test (PMRT) and in a hallway with decreasing width. The virtual simulator was displayed on computer screen and VR screens and participants interacted with it using a set of instrumented rollers and a wheelchair joystick. Driving performances of participants were estimated and compared using quantitative metrics from the simulator. Qualitative ratings from two experienced clinicians were used to estimate intra- and inter-rater reliability. Results Ten regular wheelchair users (seven men, three women; mean age ± SD, 39.5 ± 15.39 years) participated. The virtual PMRT scores from the two clinicians show high inter-rater reliability (78–90%) and high intra-rater reliability (71–90%) for all test conditions. More research is required to explore user preferences and effectiveness of the two control methods (rollers and mathematical model) and the display screens. Conclusions The virtual driving simulator seems to be a promising tool for wheelchair driving assessment that clinicians can use to supplement their real-world evaluations. PMID:23820148

  17. Design and Simulation of an Electrothermal Actuator Based Rotational Drive

    NASA Astrophysics Data System (ADS)

    Beeson, Sterling; Dallas, Tim

    2008-10-01

    As a participant in the Micro and Nano Device Engineering (MANDE) Research Experience for Undergraduates program at Texas Tech University, I learned how MEMS devices operate and the limits of their operation. Using specialized AutoCAD-based design software and the ANSYS simulation program, I learned the MEMS fabrication process used at Sandia National Labs, the design limitations of this process, the abilities and drawbacks of micro devices, and finally, I redesigned a MEMS device called the Chevron Torsional Ratcheting Actuator (CTRA). Motion is achieved through electrothermal actuation. The chevron (bent-beam) actuators cause a ratcheting motion on top of a hub-less gear so that as voltage is applied the CTRA spins. The voltage applied needs to be pulsed and the frequency of the pulses determine the angular frequency of the device. The main objective was to design electromechanical structures capable of transforming the electrical signals into mechanical motion without overheating. The design was optimized using finite element analysis in ANSYS allowing multi-physics simulations of our model system.

  18. Study of scratch drive actuator force characteristics

    NASA Astrophysics Data System (ADS)

    Li, Lijie; Brown, J. Gordon; Uttamchandani, Deepak

    2002-11-01

    Microactuators are one of the key components in MEMS technology, and various designs have been realized through different fabrication processes. One type of microactuator commonly used is the scratch drive actuator (SDA) that is frequently fabricated by surface micromachining processes. An experimental investigation has been conducted on the force characteristics of SDAs fabricated using the JDSU Microsystems MUMPs process. One-, two-, three- and four-plate SDAs connected to box-springs have been designed and fabricated for these experiments using MUMPs run 44. The spring constant for the box-springs has been calculated by FEM using ANSYS software. The product of the spring constant and spring extension is used to measure the forces produced by these SDAs. It is estimated that the forces produced exceed 250 μN from a one-plate SDA and 850 μN from a four-plate SDA.

  19. Simulations of NOVA direct-drive Rayleigh-Taylor experiments

    SciTech Connect

    Weber, S.V.

    1990-11-03

    Directly driven Rayleigh-Taylor instability growth experiments being performed on NOVA have been simulated using the computer code, LASNEX. These experiments employ beams smoothed with random phase plates (RPP), and will later include smoothing by spectral dispersion (SSD). Samples are CH foils with or without imposed sinusoidal surface perturbations. Perturbation growth is diagnosed by means of x-ray backlighting. Calculated growth rates are fairly flat across the wavelength range of 20--80 {mu}m which can be accessed experimentally, and are moderately suppressed below classical growth rates. Perturbations of large enough initial amplitude that the contrast in the x-ray image is measurable from the start of the experiment quickly grow into the nonlinear regime. Smaller initial amplitudes result in a longer interval of linear growth, but the initial perturbation will not be detectable in the data. Structure which is predicted to develop from speckles in the RPP beam pattern, with and without SSD, is also presented.

  20. Naturalistic Teenage Driving Study: Findings and Lessons Learned

    PubMed Central

    Simons-Morton, Bruce G.; Klauer, Sheila G.; Ouimet, Marie Claude; Guo, Feng; Albert, Paul S.; Lee, Suzanne E.; Ehsani, Johnathon P.; Pradhan, Anuj K.; Dingus, Thomas A.

    2015-01-01

    Problem This paper summarizes the findings on novice teenage driving outcomes (e.g., crashes and risky driving behaviors) from the Naturalistic Teenage Driving Study. Method Survey and driving data from a data acquisition system (Global Positioning System, accelerometers, cameras) were collected from 42 newly-licensed teenage drivers and their parents during the first 18 months of teenage licensure; stress responsivity was also measured in teenagers. Result Overall teenage crash and near crash (CNC) rates declined over time, but were >4 times higher among teenagers than adults. Contributing factors to teenage CNC rates included secondary task engagement (e.g., distraction), kinematic risky driving, low stress responsivity, and risky social norms. Conclusion The data support the contention that the high novice teenage CNC risk is due both to inexperience and risky driving behavior, particularly kinematic risky driving and secondary task engagement. Practical Applications Graduated driver licensing policy and other prevention efforts should focus on kinematic risky driving, secondary task engagement, and risky social norms. PMID:26403899

  1. Blue-Enriched White Light Enhances Physiological Arousal But Not Behavioral Performance during Simulated Driving at Early Night.

    PubMed

    Rodríguez-Morilla, Beatriz; Madrid, Juan A; Molina, Enrique; Correa, Angel

    2017-01-01

    Vigilance usually deteriorates over prolonged driving at non-optimal times of day. Exposure to blue-enriched light has shown to enhance arousal, leading to behavioral benefits in some cognitive tasks. However, the cognitive effects of long-wavelength light have been less studied and its effects on driving performance remained to be addressed. We tested the effects of a blue-enriched white light (BWL) and a long-wavelength orange light (OL) vs. a control condition of dim light on subjective, physiological and behavioral measures at 21:45 h. Neurobehavioral tests included the Karolinska Sleepiness Scale and subjective mood scale, recording of distal-proximal temperature gradient (DPG, as index of physiological arousal), accuracy in simulated driving and reaction time in the auditory psychomotor vigilance task. The results showed that BWL decreased the DPG (reflecting enhanced arousal), while it did not improve reaction time or driving performance. Instead, blue light produced larger driving errors than OL, while performance in OL was stable along time on task. These data suggest that physiological arousal induced by light does not necessarily imply cognitive improvement. Indeed, excessive arousal might deteriorate accuracy in complex tasks requiring precision, such as driving.

  2. Blue-Enriched White Light Enhances Physiological Arousal But Not Behavioral Performance during Simulated Driving at Early Night

    PubMed Central

    Rodríguez-Morilla, Beatriz; Madrid, Juan A.; Molina, Enrique; Correa, Angel

    2017-01-01

    Vigilance usually deteriorates over prolonged driving at non-optimal times of day. Exposure to blue-enriched light has shown to enhance arousal, leading to behavioral benefits in some cognitive tasks. However, the cognitive effects of long-wavelength light have been less studied and its effects on driving performance remained to be addressed. We tested the effects of a blue-enriched white light (BWL) and a long-wavelength orange light (OL) vs. a control condition of dim light on subjective, physiological and behavioral measures at 21:45 h. Neurobehavioral tests included the Karolinska Sleepiness Scale and subjective mood scale, recording of distal-proximal temperature gradient (DPG, as index of physiological arousal), accuracy in simulated driving and reaction time in the auditory psychomotor vigilance task. The results showed that BWL decreased the DPG (reflecting enhanced arousal), while it did not improve reaction time or driving performance. Instead, blue light produced larger driving errors than OL, while performance in OL was stable along time on task. These data suggest that physiological arousal induced by light does not necessarily imply cognitive improvement. Indeed, excessive arousal might deteriorate accuracy in complex tasks requiring precision, such as driving. PMID:28690558

  3. Using self-reported data to assess the validity of driving simulation data.

    PubMed

    Reimer, Bryan; D'Ambrosio, Lisa A; Coughlin, Joseph E; Kafrissen, Michael E; Biederman, Joseph

    2006-05-01

    In this article, we use self-reported driving behaviors from a written questionnaire to assess the measurement validity of data derived from a driving simulation. The issue of validity concerns the extent to which measures from the experimental context map onto constructs of interest. Following a description of the experimental methods and setting, an argument for the face validity of the data is advanced. Convergent validity was assessed by regressing behaviors observed in thedriving simulatoron self-reported measures of driving behaviors. Significant relationships were found across six measures: accidents, speeding, velocity, passing, weaving between traffic, and behavior at stop signs. Concurrent validity was evaluated with an analysis of simulator accident involvement and attention deficit hyperactivity disorder status. Discriminant validity was assessed using a multitrait-multimethod matrix of simulator and questionnaire data. We concluded that although the relationship between self-reported behaviors and observed responses in the simulator falls short of perfect correspondence, the data collected from the driving simulator are valid measures of the behaviors of interest.

  4. Acute alcohol tolerance on subjective intoxication and simulated driving performance in binge drinkers.

    PubMed

    Marczinski, Cecile A; Fillmore, Mark T

    2009-06-01

    High rates of binge drinking and alcohol-related problems, including drinking and driving, occur among college students. Underlying reasons for the heightened impaired driving rates in this demographic group are not known. The authors hypothesized that acute tolerance to the interoceptive cues of intoxication may contribute to these maladaptive decisions to drive in binge drinkers. Groups of binge-drinking and non-binge-drinking college students (N = 28) attended sessions during which they received a moderate dose of alcohol (0.65 g/kg) or a placebo. The development of acute tolerance to subjective ratings of intoxication and simulated driving performance was assessed by comparing measures taken during the ascending phase and descending phases of the blood alcohol curve. Compared with placebo, alcohol increased ratings of intoxication and impaired multiple aspects of simulated driving performance in both binge and non-binge drinkers. During the descending phase of the blood alcohol curve, binge drinkers showed acute tolerance to alcohol's effect on subjective intoxication, and this effect was accompanied by an increased rating of willingness to drive. By contrast, non-binge drinkers showed no acute tolerance. Copyright (c) 2009 APA, all rights reserved.

  5. Evaluation of blue light exposure to beta brainwaves on simulated night driving

    NASA Astrophysics Data System (ADS)

    Purawijaya, Dandri Aly; Fitri, Lulu Lusianti; Suprijanto

    2015-09-01

    Numbers of night driving accident in Indonesia since 2010 are exponentially rising each year with total of loss more than 50 billion rupiah. One of the causes that contribute to night driving accident is drowsiness. Drowsiness is affected by circadian rhythm resulted from the difference of blue light quality and quantity between night and day. Blue light may effect on human physiology through non-visual pathway by suppressing melatonin hormone suppression that influence drowsiness. Meanwhile, the production of hormones and other activities in brain generate bioelectrical activity such as brainwaves and can be recorded using Electroencephalograph (EEG). Therefore, this research objective is to evaluate the effect of blue light exposure to beta brainwave emergence during night driving simulation to a driver. This research was conducted to 4 male subjects who are able to drive and have a legitimate car driving license. The driving simulator was done using SCANIA Truck Driving Simulator on freeform driving mode in dark environment. Subjects drove for total 32 minutes. The data collections were taken in 2 days with 16 minutes for each day. The 16 minutes were divided again into 8 minutes adaptation in dark and 8 minutes for driving either in blue light exposure or in total darkness. While driving the simulation, subjects' brainwaves were recorded using EEG EMOTIV 14 Channels, exposed by LED monochromatic blue light with 160 Lux from source and angle 45o and sat 1 m in front of the screen. Channels used on this research were for visual (O1; O2), cognition (F3; F4; P7; P8), and motor (FC5; FC6). EEG brainwave result was filtered with EEGLab to obtain beta waves at 13 - 30 Hz frequencies. Results showed that beta waves response to blue light varied for each subject. Blue light exposure either increased or decreased beta waves in 2 minutes pattern and maintaining beta waves on cognition and motor area in 3 out of 4 subjects. Meanwhile, blue light exposure did not maintain

  6. A brief peripheral motion contrast threshold test predicts older drivers' hazardous behaviors in simulated driving.

    PubMed

    Henderson, Steven; Woods-Fry, Heather; Collin, Charles A; Gagnon, Sylvain; Voloaca, Misha; Grant, John; Rosenthal, Ted; Allen, Wade

    2015-05-01

    Our research group has previously demonstrated that the peripheral motion contrast threshold (PMCT) test predicts older drivers' self-report accident risk, as well as simulated driving performance. However, the PMCT is too lengthy to be a part of a battery of tests to assess fitness to drive. Therefore, we have developed a new version of this test, which takes under two minutes to administer. We assessed the motion contrast thresholds of 24 younger drivers (19-32) and 25 older drivers (65-83) with both the PMCT-10min and the PMCT-2min test and investigated if thresholds were associated with measures of simulated driving performance. Younger participants had significantly lower motion contrast thresholds than older participants and there were no significant correlations between younger participants' thresholds and any measures of driving performance. The PMCT-10min and the PMCT-2min thresholds of older drivers' predicted simulated crash risk, as well as the minimum distance of approach to all hazards. This suggests that our tests of motion processing can help predict the risk of collision or near collision in older drivers. Thresholds were also correlated with the total lane deviation time, suggesting a deficiency in processing of peripheral flow and delayed detection of adjacent cars. The PMCT-2min is an improved version of a previously validated test, and it has the potential to help assess older drivers' fitness to drive. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Driving Coronal MHD Simulations with Flux Evolution Models

    NASA Astrophysics Data System (ADS)

    Linker, J.; Lionello, R.; Mikic, Z.; Riley, P.; Downs, C.; Arge, C. N.; Henney, C. J.

    2013-12-01

    The solar corona and solar wind strongly influences space weather at Earth. While coronal mass ejections (CMEs) are the most obvious source of this influence, the structure and dynamics of the ambient solar corona and solar wind also play an important role. Coronal structure leads to the partitioning of the solar wind into fast and slow streams, which are the source of recurrent geomagnetic activity. The geo-effectiveness of CMEs is in part determined by their interaction with the ambient wind, and the connection of the ambient interplanetary magnetic field to CME-related shocks and impulsive solar flares determines where solar energetic particles propagate. MHD simulations of the solar corona based on maps of the solar magnetic field have been demonstrated to describe many aspects of coronal structure. However, these models are typically integrated to steady state, using synoptic or daily-updated magnetic maps to derive the boundary conditions. The Sun's magnetic flux is always evolving, and these changes in the flux affect the structure and dynamics of the corona and heliosphere. In this presentation, we describe an approach to evolutionary models of the corona and so wind, using time-dependent boundary conditions. A key aspect of our approach is the use of the Air Force Data Assimilative Photospheric flux Transport (ADAPT) model to develop time-evolving boundary conditions for the magnetic field. ADAPT incorporates data assimilation techniques into the Worden and Harvey (2000) flux evolution model, making it an especially suitable candidate for providing boundary conditions to MHD models. We describe initial results and compare them with more traditional approaches. Research supported by AFOSR, NASA, and NSF.

  8. Modeling, Simulation Design and Control of Hybrid-Electric Vehicle Drives

    SciTech Connect

    Giorgio Rizzoni

    2005-09-30

    Ohio State University (OSU) is uniquely poised to establish such a center, with interdisciplinary emphasis on modeling, simulation, design and control of hybrid-electric drives for a number of reasons, some of which are: (1) The OSU Center for Automotive Research (CAR) already provides an infrastructure for interdisciplinary automotive research and graduate education; the facilities available at OSU-CAR in the area of vehicle and powertrain research are among the best in the country. CAR facilities include 31,000 sq. feet of space, multiple chassis and engine dynamometers, an anechoic chamber, and a high bay area. (2) OSU has in excess of 10 graduate level courses related to automotive systems. A graduate level sequence has already been initiated with GM. In addition, an Automotive Systems Engineering (ASE) program cosponsored by the mechanical and electrical engineering programs, had been formulated earlier at OSU, independent of the GATE program proposal. The main objective of the ASE is to provide multidisciplinary graduate education and training in the field of automotive systems to Masters level students. This graduate program can be easily adapted to fulfill the spirit of the GATE Center of Excellence. (3) A program in Mechatronic Systems Engineering has been in place at OSU since 1994; this program has a strong emphasis on automotive system integration issues, and has emphasized hybrid-electric vehicles as one of its application areas. (4) OSU researchers affiliated with CAR have been directly involved in the development and study of: HEV modeling and simulation; electric drives; transmission design and control; combustion engines; and energy storage systems. These activities have been conducted in collaboration with government and automotive industry sponsors; further, the same researchers have been actively involved in continuing education programs in these areas with the automotive industry. The proposed effort will include: (1) The development of a

  9. A method for predicting the risk of virtual crashes in a simulated driving task using behavioural and subjective drowsiness measures.

    PubMed

    Murata, Atsuo; Naitoh, Kensuke; Karwowski, Waldemar

    2016-08-29

    This study proposed a procedure for predicting the point in time with high risk of virtual crash using a control chart methodology for behavioural measures during a simulated driving task. Tracking error, human back pressure, sitting pressure and horizontal and vertical neck bending angles were measured during the simulated driving task. The time with a high risk of a virtual crash occurred in 9 out of 10 participants. The time interval between the successfully detected point in time with high risk of virtual crash and the point in time of virtual crash ranged from 80 to 324 s. The proposed procedure for predicting the point in time with a high risk of a crash is promising for warning drivers of the state of high risk of crash. Practitioner Summary: Many fatal crashes occur due to drowsy driving. We proposed a method to predict the point in time with high risk of virtual crash before such a virtual crash occurs. This is done using behavioural measures during a simulated driving task. The effectiveness of the method is also demonstrated.

  10. Simulation of multilane freeway traffic with detailed rules deduced from microscopic driving behavior

    PubMed

    Goldbach; Eidmann; Kittel

    2000-02-01

    A simulation to model traffic on a multilane freeway is introduced starting from microscopic driving rules. The model takes each individual car into account with its individual features and actual situations, so that a distribution of parameters as well as different behaviors can easily be analyzed. Therefore, a detailed study of certain situations, driving tactics, vehicle properties, and their influence on the global traffic flow can be performed. The model is discussed, as are first results such as the influence of driver behavior on the fundamental diagram and, in addition, the dynamics of microscopic, individual quantities like separation and difference in speed between successive cars. It turns out that a hysteresis in the reaction of the driver for speeding up and slowing down plays an important role, and effects macroscopic quantities like the shape of the fundamental diagram, e.g., the metastable behavior around the maximum flow and on the speed of observed jams running backward. Furthermore, microscopic time resolved characteristics are strongly influenced, e.g., oscillations in the distance and relative speed between successive cars.

  11. Referential coding of steering-wheel button presses in a simulated driving cockpit.

    PubMed

    Xiong, Aiping; Proctor, Robert W

    2015-12-01

    The present study investigated whether left and right pushbuttons on a steering wheel are coded relative to an "infotainment display" in a simulated driving cockpit. Participants performed a go/no-go Simon task in which they responded on trials for which a tone, presented from a left or right speaker, was 1 of 2 pitches (low or high) with a single button press (left in 1 trial block; right in another). Without the infotainment display in Experiment 1, both left and right responses showed Simon effects of similar size. In both Experiments 2 and 3, the infotainment display was located to the right or left, and the Simon effect was smaller for the response that was on the side of the infotainment display than for the response that was on the opposite side. The results indicate that in a driving cockpit environment, the pushbutton responses are coded as left and right with respect not only to the wheel-based frame but also to a salient object like the infotainment display. The general point for application is that the driver's spatial representation of responses, and consequently performance, can be influenced by multiple frames of reference. (c) 2015 APA, all rights reserved).

  12. A driving simulator evaluation of potential speed reductions using two innovative designs for signalised urban intersections.

    PubMed

    Stephens, Amanda N; Beanland, Vanessa; Candappa, Nimmi; Mitsopoulos-Rubens, Eve; Corben, Bruce; Lenné, Michael G

    2017-01-01

    Intersections are typically associated with a higher level of crash risk than other types of facilities on the road network. Standard cross-road intersections are particularly hazardous because by their very design, drivers may travel through at speeds that are incompatible with human biomechanical tolerance should a crash occur. Further, drivers are exposed to dangerous conflict angles, which are likely to result in serious injury. This paper examines the effectiveness of two new intersection designs aimed at restricting potentially dangerous conflict angles while reducing driver speeds through the intersection. These designs, named the "Cut-Through" and the "Squircle", incorporate key features of both signalised intersections and roundabouts. The intersections are controlled by signals similar to a signalised roundabout. Instead of a standard central island, right turning traffic (equivalent to left turns in jurisdictions that drive on the right) cut through the central island, thereby avoiding traffic interlocks and delays that can occur with the traditional signalised roundabout. Across two driving simulator studies, vehicle speed data were collected on approach to and through each of the proposed intersection designs. Performance was benchmarked against equivalent standard signalised cross-road intersections and standard non-signalised roundabouts. Notably, drivers reduced their speeds by approximately 30-40% when negotiating both the Cut-Through and the Squircle compared to the standard signalised intersections. The safety potentials of the two new intersection designs are discussed within the guidelines of the Safe Systems principles. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Reactivity-controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle system simulations

    DOE PAGES

    Curran, Scott J.; Gao, Zhiming; Wagner, Robert M.

    2014-12-22

    In-cylinder blending of gasoline and diesel to achieve reactivity-controlled compression ignition has been shown to reduce NOX and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion. The reactivity-controlled compression ignition concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load, allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. In this paper, a multi-mode reactivity-controlled compression ignition strategy is employed where the engine switches from reactivity-controlled compression ignition to conventional diesel combustion whenmore » speed and load demand are outside of the experimentally determined reactivity-controlled compression ignition range. The potential for reactivity-controlled compression ignition to reduce drive cycle fuel economy and emissions is not clearly understood and is explored here by simulating the fuel economy and emissions for a multi-mode reactivity-controlled compression ignition–enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode reactivity-controlled compression ignition, conventional diesel combustion, and a 2009 port-fuel injected gasoline engine. Drive cycle simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. Multi-mode reactivity-controlled compression ignition fuel economy simulation results are compared with the same vehicle powered by a representative 2009 port-fuel injected gasoline engine over multiple drive cycles. Finally, engine-out drive cycle emissions are compared with conventional diesel combustion, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.« less

  14. Reactivity-controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle system simulations

    SciTech Connect

    Curran, Scott J.; Gao, Zhiming; Wagner, Robert M.

    2014-12-22

    In-cylinder blending of gasoline and diesel to achieve reactivity-controlled compression ignition has been shown to reduce NOX and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion. The reactivity-controlled compression ignition concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load, allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. In this paper, a multi-mode reactivity-controlled compression ignition strategy is employed where the engine switches from reactivity-controlled compression ignition to conventional diesel combustion when speed and load demand are outside of the experimentally determined reactivity-controlled compression ignition range. The potential for reactivity-controlled compression ignition to reduce drive cycle fuel economy and emissions is not clearly understood and is explored here by simulating the fuel economy and emissions for a multi-mode reactivity-controlled compression ignition–enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode reactivity-controlled compression ignition, conventional diesel combustion, and a 2009 port-fuel injected gasoline engine. Drive cycle simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. Multi-mode reactivity-controlled compression ignition fuel economy simulation results are compared with the same vehicle powered by a representative 2009 port-fuel injected gasoline engine over multiple drive cycles. Finally, engine-out drive cycle emissions are compared with conventional diesel combustion, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.

  15. Texting while driving: A study of 1211 U.S. adults with the Distracted Driving Survey.

    PubMed

    Gliklich, Emily; Guo, Rong; Bergmark, Regan W

    2016-12-01

    Texting and other cell-phone related distracted driving is estimated to account for thousands of motor vehicle collisions each year but studies examining the specific cell phone reading and writing activities of drivers are limited. The objective of this study was to describe the frequency of cell-phone related distracted driving behaviors. A national, representative, anonymous panel of 1211 United States drivers was recruited in 2015 to complete the Distracted Driving Survey (DDS), an 11-item validated questionnaire examining cell phone reading and writing activities and at what speeds they occur. Higher DDS scores reflect more distraction. DDS scores were analyzed by demographic data and self-reported crash rate. Nearly 60% of respondents reported a cell phone reading or writing activity within the prior 30 days, with reading texts (48%), writing texts (33%) and viewing maps (43%) most frequently reported. Only 4.9% of respondents had enrolled in a program aimed at reducing cell phone related distracted driving. DDS scores were significantly correlated to crash rate (p < 0.0001), with every one point increase associated with an additional 7% risk of a crash (p < 0.0001). DDS scores were inversely correlated to age (p < 0.0001). The DDS demonstrated high internal consistency (Cronbach's alpha = 0.94). High rates of cell phone-related distraction are reported here in a national sample. Distraction is associated with crash rates and occurs across all age groups, but is highest in younger drivers. The DDS can be used to evaluate the impact of public health programs aimed at reducing cell-phone related distracted driving.

  16. Useful visual field reduction as a function of age and risk of accident in simulated car driving.

    PubMed

    Rogé, Joceline; Pébayle, Thierry; Campagne, Aurélie; Muzet, Alain

    2005-05-01

    To study the relationships between the reduction of the useful visual field, age, and driving performance. Forty-eight subjects, aged from 23 to 77 years performed a test to evaluate the size of their useful visual fields. The test involved the detection and localization of peripheral signals that could appear in an area of 70 degrees of visual angle. The subjects then performed a simulated car-driving task involving the management of a situation that could lead to an accident. The analysis of the data revealed that the ability to process peripheral signals and simulated driving performance (vehicle speed) deteriorate with age. Simulated driving performance and useful visual field measurement have been analyzed jointly. The results indicate that the reduction of the useful visual field, estimated using a target-localization task, is related to the individual's ability to manage the simulated driving situation (correlation coefficient with speed = -0.43 and with reaction time for avoidance of a mobile obstacle = +0.30) and the deterioration of the useful visual field estimated using a target detection task is related only to vehicle speed (correlation coefficient = -0.32). The adoption of a lower speed by the drivers with a reduced visual field (the elderly ones) is probably an adaptation strategy to process the peripheral information. All useful visual field measurements do not seem to be equivalent to estimate the ability to process information relative to the mobile obstacle. The risk of collision should be estimated only with a useful visual field test using a target localization task.

  17. Two-Dimensional Simulations of Plastic-Shell, Direct-Drive Implosions on OMEGA

    SciTech Connect

    Radha, P.B.; Goncharov, V.N.; Collins, T.J.B.; Delettrez, J.A.; Elbaz, Y.; Glebov, V.Yu.; Keck, R.L.; Keller, D.E.; Knauer, J.P.; Marozas, J.A.; Marshall, F.J.; McKenty, P.W.; Meyerhofer, D.D.; Regan, S.P.; Sangster, T.C.; Shvarts, D.; Skupsky, S.; Srebro, Y.; Town, R.P.J.; Stoeckl, C.

    2005-02-18

    Multidimensional hydrodynamic properties of high-adiabat direct-drive plastic-shell implosions on the OMEGA laser system are investigated using the multidimensional hydrodynamic code, DRACO. Multimode simulations including the effects of nonuniform illumination and target roughness indicate that shell stability during the acceleration phase plays a critical role in determining target performance.

  18. Increasing Following Headway with Prompts, Goal Setting, and Feedback in a Driving Simulator

    ERIC Educational Resources Information Center

    Arnold, Michelle L.; Van Houten, Ron

    2011-01-01

    We evaluated the effects of prompting, goal setting, and feedback on following headway of young drivers in a simulated driving environment and assessed whether changes produced in following headway were associated with reductions in hard braking when drivers were and were not using cell phones. Participants were 4 university students. During…

  19. Angular radiation temperature simulation for time-dependent capsule drive prediction in inertial confinement fusion

    SciTech Connect

    Jing, Longfei; Yang, Dong; Li, Hang; Zhang, Lu; Lin, Zhiwei; Li, Liling; Kuang, Longyu; Jiang, Shaoen Ding, Yongkun; Huang, Yunbao

    2015-02-15

    The x-ray drive on a capsule in an inertial confinement fusion setup is crucial for ignition. Unfortunately, a direct measurement has not been possible so far. We propose an angular radiation temperature simulation to predict the time-dependent drive on the capsule. A simple model, based on the view-factor method for the simulation of the radiation temperature, is presented and compared with the experimental data obtained using the OMEGA laser facility and the simulation results acquired with VISRAD code. We found a good agreement between the time-dependent measurements and the simulation results obtained using this model. The validated model was then used to analyze the experimental results from the Shenguang-III prototype laser facility. More specifically, the variations of the peak radiation temperatures at different view angles with the albedo of the hohlraum, the motion of the laser spots, the closure of the laser entrance holes, and the deviation of the laser power were investigated. Furthermore, the time-dependent radiation temperature at different orientations and the drive history on the capsule were calculated. The results indicate that the radiation temperature from “U20W112” (named according to the diagnostic hole ID on the target chamber) can be used to approximately predict the drive temperature on the capsule. In addition, the influence of the capsule on the peak radiation temperature is also presented.

  20. Increasing Following Headway with Prompts, Goal Setting, and Feedback in a Driving Simulator

    ERIC Educational Resources Information Center

    Arnold, Michelle L.; Van Houten, Ron

    2011-01-01

    We evaluated the effects of prompting, goal setting, and feedback on following headway of young drivers in a simulated driving environment and assessed whether changes produced in following headway were associated with reductions in hard braking when drivers were and were not using cell phones. Participants were 4 university students. During…

  1. Astronaut John Young drives in One-G Lunar Roving Vehicle during simulation

    NASA Image and Video Library

    1971-03-04

    Astronaut John W. Young, Apollo 16 prime crew commander (right), takes a drive in the One-G Lunar Roving Vehicle (LRV) trainer in the Lunar Topgraphic Simulation area at the Manned Spacecraft Center (MSC). He is accompanied by John Omstead, with General Electric, MSC.

  2. The application of integral performance criteria to the analysis of discrete maneuvers in a driving simulator

    NASA Technical Reports Server (NTRS)

    Repa, B. S.; Zucker, R. S.; Wierwille, W. W.

    1977-01-01

    The influence of vehicle transient response characteristics on driver-vehicle performance in discrete maneuvers as measured by integral performance criteria was investigated. A group of eight ordinary drivers was presented with a series of eight vehicle transfer function configurations in a driving simulator. Performance in two discrete maneuvers was analyzed by means of integral performance criteria. Results are presented.

  3. Sequential Dependencies in Driving

    ERIC Educational Resources Information Center

    Doshi, Anup; Tran, Cuong; Wilder, Matthew H.; Mozer, Michael C.; Trivedi, Mohan M.

    2012-01-01

    The effect of recent experience on current behavior has been studied extensively in simple laboratory tasks. We explore the nature of sequential effects in the more naturalistic setting of automobile driving. Driving is a safety-critical task in which delayed response times may have severe consequences. Using a realistic driving simulator, we find…

  4. Sequential Dependencies in Driving

    ERIC Educational Resources Information Center

    Doshi, Anup; Tran, Cuong; Wilder, Matthew H.; Mozer, Michael C.; Trivedi, Mohan M.

    2012-01-01

    The effect of recent experience on current behavior has been studied extensively in simple laboratory tasks. We explore the nature of sequential effects in the more naturalistic setting of automobile driving. Driving is a safety-critical task in which delayed response times may have severe consequences. Using a realistic driving simulator, we find…

  5. Kinetic simulation of direct-drive capsule implosions and its comparison with experiments and radiation hydrodynamic simulation

    NASA Astrophysics Data System (ADS)

    Kwan, Thomas; Le, Ari; Schmitt, Mark; Herrmann, Hans; Batha, Steve

    2015-11-01

    We have carried out simulations of direct-drive capsule implosion experiments conducted on Omega laser facility at the Laboratory of Laser energetics of the University of Rochester. The capsules had a glass shell (SiO2) with D, T, He-3 fills at various proportions. One-dimensional radiation hydrodynamic calculations and kinetic particle/hybrid simulations with LSP were carried out for the post-shot analysis to compare neutron yield, yield ratio, and shell convergence in assessing the effects of plasma kinetic effects. The LSP simulations were initiated with the output from the rad-hydro simulations at the end of the laser-drive. The electrons are treated as a fluid while all the ion species by the kinetic PIC technique. Our LSP simulations clearly showed species separation between the deuterons, tritons and He-3 during the implosion but significantly less after the compression. The neutron yield, gamma bang-time and -width from the LSP simulations compared favorably with experiments. Detail comparison among the kinetic simulations, rad-hydro simulations, and experimental results will be presented. Work performed under the auspices of the US Department of Energy by Los Alamos National Laboratory under Contract No. W-7405-ENG-36.

  6. Chronotype, sleep loss, and diurnal pattern of salivary cortisol in a simulated daylong driving.

    PubMed

    Oginska, Halszka; Fafrowicz, Magdalena; Golonka, Krystyna; Marek, Tadeusz; Mojsa-Kaja, Justyna; Tucholska, Kinga

    2010-07-01

    The study focused on chronotype-related differences in subjective load assessment, sleepiness, and salivary cortisol pattern in subjects performing daylong simulated driving. Individual differences in work stress appraisal and psychobiological cost of prolonged load seem to be of importance in view of expanding compressed working time schedules. Twenty-one healthy, male volunteers (mean +/- SD: 27.9 +/- 4.9 yrs) were required to stay in semiconstant routine conditions. They performed four sessions (each lasting approximately 2.5 h) of simulated driving, i.e., completed chosen tasks from computer driving games. Saliva samples were collected after each driving session, i.e., at 10:00-11:00, 14:00-15:00, 18:00-19:00, and 22:00-23:00 h as well as 10-30 min after waking (between 05:00 and 06:00 h) and at bedtime (after 00:00 h). Two subgroups of subjects were distinguished on the basis of the Chronotype Questionnaire: morning (M)- and evening (E)-oriented types. Subjective data on sleep need, sleeping time preferences, sleeping problems, and the details of the preceding night were investigated by questionnaire. Subjective measures of task load (NASA Task Load Index [NASA-TLX]), activation (Thayer's Activation-Deactivation Adjective Check List [AD ACL]), and sleepiness (Karolinska Sleepiness Scale [KSS]) were applied at times of saliva samples collection. M- and E-oriented types differed significantly as to their ideal sleep length (6 h 54 min +/- 44 versus 8 h 13 min +/- 50 min), preferred sleep timing (midpoint at 03:19 versus 04:26), and sleep index, i.e., 'real-to-ideal' sleep ratio, before the experimental day (0.88 versus 0.67). Sleep deficit proved to be integrated with eveningness. M and E types exhibited similar diurnal profiles of energy, tiredness, tension, and calmness assessed by AD ACL, but E types estimated higher their workload (NASA-TLX) and sleepiness (KSS). M types exhibited a trend of higher mean cortisol levels than E types (F = 4.192, p < .056) and

  7. Driving Simulation as a Performance-based Test of Visual Impairment in Glaucoma

    PubMed Central

    Medeiros, Felipe A.; Weinreb, Robert N.; Boer, Erwin; Rosen, Peter N.

    2013-01-01

    The fundamental goal of glaucoma management is to prevent patients from developing visual impairment sufficient to produce disability in their daily lives and impair their quality of life. Ultimately, patients are interested in how their vision will impact their ability to perform daily activities, such as driving. Although technological advancements such as automated perimetry and devices for optic nerve imaging have resulted in great improvement in our ability to quantify structural and functional damage in glaucoma, the impact on vision-related quality of life of some of the information acquired from these tests remain elusive. On the other hand, performance-based measures may be better correlated to traditional measures of vision health and, more importantly, they provide a more direct measure of disability. Driving simulators can be used as a performance-based test for evaluation of functional impairment in glaucoma. Their use can potentially help the evaluation of driving safety and performance of diseased subjects and provide insight into the different mechanisms involved in causing driving impairment in this disease. The ability to do this in an experimentally controlled and standardized setting enables testing of a much larger number of hypotheses compared to on-road evaluations. Besides evaluating driver fitness, simulators could also potentially be used as a sophisticated test to evaluate cognitive impairment in the context of an everyday task (driving) that has not been available through traditional neuropsychological assessment. PMID:21467952

  8. Effects of conversation on situation awareness and working memory in simulated driving.

    PubMed

    Heenan, Adam; Herdman, Chris M; Brown, Matthew S; Robert, Nicole

    2014-09-01

    In the present research, we investigated the hypothesis that working memory mediates conversation-induced impairment of situation awareness (SA) while driving. Although there is empirical evidence that conversation impairs driving performance, the cognitive mechanisms that mediate this relationship remain underspecified. Researchers have reported that a phonological working memory task decreased drivers' SA for vehicles located behind them whereas a visuospatial working memory task impaired SA for vehicles ahead. Conversation, therefore, might impair SA for vehicles behind the driver by preferentially taxing the phonological loop. A 20-questions task was used as a proxy for natural conversation. In Experiment I, driving performance was measured across three within-subjects conversation conditions (i.e., no conversation, driver asks questions, driver answers questions) with the use of a driving simulator. In Experiment 2, participants drove in the same simulator while either conversing (20-questions task) or not Participants estimated the positions of other vehicles after the screens were blanked at the end of each trial. Speed monitoring and responses to visual probes were impaired by the 20-questions conversation task (Experiment 1). As predicted, conversation impaired SA for the location of other vehicles more for vehicles located behind the driver than for those in front (Experiment 2). Conversation impairs drivers' SA of vehicles behind them by taxing working memory's phonological loop and impairs SA generally by taxing working memory's central executive. Provides a theoretical framework that links driver SA to working memory and a mechanism for understanding why conversation impairs driving performance.

  9. Simulating the dynamic behavior of chain drive systems by advanced CAE programs

    SciTech Connect

    Ross, J.; Meyer, J.

    1996-09-01

    Due to the increased requirements for chain drive systems of 4-stroke internal combustion engines CAE-tools are necessary to design the optimum dynamic system. In comparison to models used din the past the advantage of the new model CDD (Chain Drive Dynamics) is the capability of simulating the trajectory of each chain link around the drive system. Each chain link is represented by a mass with two degrees of freedom and is coupled to the next by a spring-damper element. The drive sprocket can be moved with a constant or non-constant speed. As in reality the other sprockets are driven by the running chain and can be excited by torques. Due to these unique model features it is possible to calculate all vibration types of the chain, polygon effects and radial or angular vibrations of the sprockets very accurately. The model includes the detailed simulation of a mechanical or a hydraulic tensioner as well. The method is ready to be coupled to other detailed calculation models (e.g. valve train systems, crankshaft, etc.). The high efficiency of the tool predicting the dynamic and acoustic behavior of a chain drive system will be demonstrated in comparison to measurements.

  10. Evaluating the Impact of Road Grade on Simulated Commercial Vehicle Fuel Economy Using Real-World Drive Cycles

    SciTech Connect

    Lopp, Sean; Wood, Eric; Duran, Adam

    2015-10-13

    Commercial vehicle fuel economy is known to vary significantly with both positive and negative road grade. Medium- and heavy-duty vehicles operating at highway speeds require incrementally larger amounts of energy to pull heavy payloads up inclines as road grade increases. Non-hybrid vehicles are then unable to recapture energy on descent and lose energy through friction braking. While the on-road effects of road grade are well understood, the majority of standard commercial vehicle drive cycles feature no climb or descent requirements. Additionally, existing literature offers a limited number of sources that attempt to estimate the on-road energy implications of road grade in the medium- and heavy-duty space. This study uses real-world commercial vehicle drive cycles from the National Renewable Energy Laboratory's Fleet DNA database to simulate the effects of road grade on fuel economy across a range of vocations, operating conditions, and locations. Drive-cycles are matched with vocation-specific vehicle models and simulated with and without grade. Fuel use due to grade is presented, and variation in fuel consumption due to drive cycle and vehicle characteristics is explored through graphical and statistical comparison. The results of this study suggest that road grade accounts for 1%-9% of fuel use in commercial vehicles on average and up to 40% on select routes.

  11. Interactions between age and moderate alcohol effects on simulated driving performance.

    PubMed

    Sklar, Alfredo L; Boissoneault, Jeff; Fillmore, Mark T; Nixon, Sara Jo

    2014-02-01

    There is a substantial body of literature documenting the deleterious effects of both alcohol consumption and age on driving performance. There is, however, limited work examining the interaction of age and acute alcohol consumption. The current study was conducted to determine if moderate alcohol doses differentially affect the driving performance of older and younger adults. Healthy older (55-70) and younger (25-35) adults were tested during a baseline session and again following consumption of one of three beverages [0.0 % (placebo), 0.04 % or 0.065 % target breath alcohol concentration]. Measures of driving precision and average speed were recorded. Older adults performed more poorly on precision driving measures and drove more slowly than younger adults at baseline. After controlling for baseline performance, interactions between alcohol and age were observed following beverage consumption on two measures of driving precision with older adults exhibiting greater impairment as a result of alcohol consumption. These data provide evidence that older adults may be more susceptible to the effects of alcohol on certain measures of driving performance. An investigation of mechanisms accounting for alcohol's effects on driving in older and younger adults is required. Further evaluation using more complex driving environments is needed to assess the real-world implication of this interaction.

  12. INTERACTIONS BETWEEN AGE AND MODERATE ALCOHOL EFFECTS ON SIMULATED DRIVING PERFORMANCE

    PubMed Central

    Sklar, Alfredo L.; Boissoneault, Jeff; Fillmore, Mark T.; Nixon, Sara Jo

    2013-01-01

    Rationale There is a substantial body of literature documenting the deleterious effects of both alcohol consumption and age on driving performance. There is, however, limited work examining the interaction of age and acute alcohol consumption. Objectives The current study was conducted to determine if moderate alcohol doses differentially affect the driving performance of older and younger adults. Methods Healthy older (55 – 70) and younger (25 – 35) adults were tested during a baseline session and again following consumption of one of three beverages (0.0% (placebo), 0.04% or 0.065% target breath alcohol concentration). Measures of driving precision and average speed were recorded. Results Older adults performed more poorly on precision driving measures and drove more slowly than younger adults at baseline. After controlling for baseline performance, interactions between alcohol and age were observed following beverage consumption on two measures of driving precision with older adults exhibiting greater impairment as a result of alcohol consumption. Conclusions These data provide evidence that older adults may be more susceptible to the effects of alcohol on certain measures of driving performance. An investigation of mechanisms accounting for alcohol’s effects on driving in older and younger adults is required. Further evaluation using more complex driving environments is needed to assess the real-world implication of this interaction. PMID:24030469

  13. Energy analysis of electric vehicles using batteries or fuel cells through well-to-wheel driving cycle simulations

    NASA Astrophysics Data System (ADS)

    Campanari, Stefano; Manzolini, Giampaolo; Garcia de la Iglesia, Fernando

    This work presents a study of the energy and environmental balances for electric vehicles using batteries or fuel cells, through the methodology of the well to wheel (WTW) analysis, applied to ECE-EUDC driving cycle simulations. Well to wheel balances are carried out considering different scenarios for the primary energy supply. The fuel cell electric vehicles (FCEV) are based on the polymer electrolyte membrane (PEM) technology, and it is discussed the possibility to feed the fuel cell with (i) hydrogen directly stored onboard and generated separately by water hydrolysis (using renewable energy sources) or by conversion processes using coal or natural gas as primary energy source (through gasification or reforming), (ii) hydrogen generated onboard with a fuel processor fed by natural gas, ethanol, methanol or gasoline. The battery electric vehicles (BEV) are based on Li-ion batteries charged with electricity generated by central power stations, either based on renewable energy, coal, natural gas or reflecting the average EU power generation feedstock. A further alternative is considered: the integration of a small battery to FCEV, exploiting a hybrid solution that allows recovering energy during decelerations and substantially improves the system energy efficiency. After a preliminary WTW analysis carried out under nominal operating conditions, the work discusses the simulation of the vehicles energy consumption when following standardized ECE-EUDC driving cycle. The analysis is carried out considering different hypothesis about the vehicle driving range, the maximum speed requirements and the possibility to sustain more aggressive driving cycles. The analysis shows interesting conclusions, with best results achieved by BEVs only for very limited driving range requirements, while the fuel cell solutions yield best performances for more extended driving ranges where the battery weight becomes too high. Results are finally compared to those of conventional internal

  14. Effectively explore metastable states of proteins by adaptive nonequilibrium driving simulations

    NASA Astrophysics Data System (ADS)

    Wan, Biao; Xu, Shun; Zhou, Xin

    2017-03-01

    Nonequilibrium drivings applied in molecular dynamics (MD) simulations can efficiently extend the visiting range of protein conformations, but might compel systems to go far away from equilibrium and thus mainly explore irrelevant conformations. Here we propose a general method, called adaptive nonequilibrium simulation (ANES), to automatically adjust the external driving on the fly, based on the feedback of the short-time average response of system. Thus, the ANES approximately keeps the local equilibrium but efficiently accelerates the global motion. We illustrate the capability of the ANES in highly efficiently exploring metastable conformations in the deca-alanine peptide and find that the 0.2 -μ s ANES approximately captures the important states and folding and unfolding pathways in the HP35 solution by comparing with the result of the recent 398 -μ s equilibrium MD simulation on Anton [S. Piana et al., Proc. Natl. Acad. Sci. USA 109, 17845 (2012), 10.1073/pnas.1201811109].

  15. Simulation verification techniques study

    NASA Technical Reports Server (NTRS)

    Schoonmaker, P. B.; Wenglinski, T. H.

    1975-01-01

    Results are summarized of the simulation verification techniques study which consisted of two tasks: to develop techniques for simulator hardware checkout and to develop techniques for simulation performance verification (validation). The hardware verification task involved definition of simulation hardware (hardware units and integrated simulator configurations), survey of current hardware self-test techniques, and definition of hardware and software techniques for checkout of simulator subsystems. The performance verification task included definition of simulation performance parameters (and critical performance parameters), definition of methods for establishing standards of performance (sources of reference data or validation), and definition of methods for validating performance. Both major tasks included definition of verification software and assessment of verification data base impact. An annotated bibliography of all documents generated during this study is provided.

  16. Driving with Central Visual Field Loss II: How Scotomas above or below the Preferred Retinal Locus (PRL) Affect Hazard Detection in a Driving Simulator

    PubMed Central

    Bowers, Alex R.; Goldstein, Robert; Peli, Eli

    2015-01-01

    We determined whether binocular central scotomas above or below the preferred retinal locus affect detection of hazards (pedestrians) approaching from the side. Seven participants with central field loss (CFL), and seven age-and sex-matched controls with normal vision (NV), each completed two sessions of 5 test drives (each approximately 10 minutes long) in a driving simulator. Participants pressed the horn when detecting pedestrians that appeared at one of four eccentricities (-14°, -4°, left, 4°, or 14°, right, relative to car heading). Pedestrians walked or ran towards the travel lane on a collision course with the participant’s vehicle, thus remaining in the same area of the visual field, assuming participant's steady forward gaze down the travel lane. Detection rates were nearly 100% for all participants. CFL participant reaction times were longer (median 2.27s, 95% CI 2.13 to 2.47) than NVs (median 1.17s, 95%CI 1.10 to 2.13; difference p<0.01), and CFL participants would have been unable to stop for 21% of pedestrians, compared with 3% for NV, p<0.001. Although the scotomas were not expected to obscure pedestrian hazards, gaze tracking revealed that scotomas did sometimes interfere with detection; late reactions usually occurred when pedestrians were entirely or partially obscured by the scotoma (time obscured correlated with reaction times, r = 0.57, p<0.001). We previously showed that scotomas lateral to the preferred retinal locus delay reaction times to a greater extent; however, taken together, the results of our studies suggest that any binocular CFL might negatively impact timely hazard detection while driving and should be a consideration when evaluating vision for driving. PMID:26332315

  17. Driving with Central Visual Field Loss II: How Scotomas above or below the Preferred Retinal Locus (PRL) Affect Hazard Detection in a Driving Simulator.

    PubMed

    Bronstad, P Matthew; Albu, Amanda; Bowers, Alex R; Goldstein, Robert; Peli, Eli

    2015-01-01

    We determined whether binocular central scotomas above or below the preferred retinal locus affect detection of hazards (pedestrians) approaching from the side. Seven participants with central field loss (CFL), and seven age-and sex-matched controls with normal vision (NV), each completed two sessions of 5 test drives (each approximately 10 minutes long) in a driving simulator. Participants pressed the horn when detecting pedestrians that appeared at one of four eccentricities (-14°, -4°, left, 4°, or 14°, right, relative to car heading). Pedestrians walked or ran towards the travel lane on a collision course with the participant's vehicle, thus remaining in the same area of the visual field, assuming participant's steady forward gaze down the travel lane. Detection rates were nearly 100% for all participants. CFL participant reaction times were longer (median 2.27s, 95% CI 2.13 to 2.47) than NVs (median 1.17s, 95%CI 1.10 to 2.13; difference p<0.01), and CFL participants would have been unable to stop for 21% of pedestrians, compared with 3% for NV, p<0.001. Although the scotomas were not expected to obscure pedestrian hazards, gaze tracking revealed that scotomas did sometimes interfere with detection; late reactions usually occurred when pedestrians were entirely or partially obscured by the scotoma (time obscured correlated with reaction times, r = 0.57, p<0.001). We previously showed that scotomas lateral to the preferred retinal locus delay reaction times to a greater extent; however, taken together, the results of our studies suggest that any binocular CFL might negatively impact timely hazard detection while driving and should be a consideration when evaluating vision for driving.

  18. Staying Connected on the Road: A Comparison of Different Types of Smart Phone Use in a Driving Simulator.

    PubMed

    McNabb, Jaimie; Gray, Rob

    2016-01-01

    Previous research on smart phone use while driving has primarily focused on phone calls and texting. Drivers are now increasingly using their phone for other activities during driving, in particular social media, which have different cognitive demands. The present study compared the effects of four different smart phone tasks on car-following performance in a driving simulator. Phone tasks were chosen that vary across two factors: interaction medium (text vs image) and task pacing (self-paced vs experimenter-paced) and were as follows: Text messaging with the experimenter (text/other-paced), reading Facebook posts (text/self-paced), exchanging photos with the experimenter via Snapchat (image, experimenter-paced), and viewing updates on Instagram (image, experimenter-paced). Drivers also performed a driving only baseline. Brake reaction times (BRTs) were significantly greater in the text-based conditions (Mean = 1.16 s) as compared to both the image-based conditions (Mean = 0.92 s) and the baseline (0.88 s). There was no significant difference between BRTs in the image-based and baseline conditions and there was no significant effect of task-pacing. Similar results were obtained for Time Headway variability. These results are consistent with the picture superiority effect found in memory research and suggest that image-based interfaces could provide safer ways to "stay connected" while driving than text-based interfaces.

  19. Staying Connected on the Road: A Comparison of Different Types of Smart Phone Use in a Driving Simulator

    PubMed Central

    McNabb, Jaimie; Gray, Rob

    2016-01-01

    Previous research on smart phone use while driving has primarily focused on phone calls and texting. Drivers are now increasingly using their phone for other activities during driving, in particular social media, which have different cognitive demands. The present study compared the effects of four different smart phone tasks on car-following performance in a driving simulator. Phone tasks were chosen that vary across two factors: interaction medium (text vs image) and task pacing (self-paced vs experimenter-paced) and were as follows: Text messaging with the experimenter (text/other-paced), reading Facebook posts (text/self-paced), exchanging photos with the experimenter via Snapchat (image, experimenter -paced), and viewing updates on Instagram (image, experimenter -paced). Drivers also performed a driving only baseline. Brake reaction times (BRTs) were significantly greater in the text-based conditions (Mean = 1.16 s) as compared to both the image-based conditions (Mean = 0.92 s) and the baseline (0.88 s). There was no significant difference between BRTs in the image-based and baseline conditions and there was no significant effect of task-pacing. Similar results were obtained for Time Headway variability. These results are consistent with the picture superiority effect found in memory research and suggest that image-based interfaces could provide safer ways to “stay connected” while driving than text-based interfaces. PMID:26886099

  20. Inertial drives for micro- and nanorobots: analytical study

    NASA Astrophysics Data System (ADS)

    Buechi, Roland; Zesch, Wolfgang; Codourey, Alain; Siegwart, Roland Y.

    1995-12-01

    The need for high precision robots dedicated to the assembly of microsystems has led to the design of new kinds of actuators able to reach very high positional accuracy over large distances. Among these, inertial sliders have received considerably interest in the last years. They have the advantage of being based on a simple principle that leads to a simple mechanical design. However, because they are based on the nonlinearity of friction, it is not easy to predict their stepsize repeatability. In order to understand the most important parameters affecting the precision of inertial drives, a theoretical study of a 1 degree of freedom inertial slider has been established. Analytical formulas describing the influence of different parameters, such as static and dynamic friction and mass distribution, have been developed. The effect of applied functions (sawtooth and parabolic), have also been studied. The theoretical cut off frequency has been found for each of the different waveforms, allowing us to predict the maximal and minimal working frequencies for the system. Thus, for each curve form, the repeatability of inertial sliders can be evaluated taking into account the uncertainties in the friction coefficients. The best suited waveforms for given constraints can therefore be selected. Simulations carried out from this have been successfully compared to experimental results.

  1. Dynamics simulation of MEMS device embedded-hard-disk-drive system

    NASA Astrophysics Data System (ADS)

    Yang, Jiaping; Chai, Jie; Lim, Boon Baun; Chen, Shixin

    2002-04-01

    Currently, hard disk drives (HHD) use rotating disks to store digital data and magnetic recording heads are flying on the disk to read/write data. The recording heads are mounted on a slider- suspension assembly, which makes heads move from one track to another on the disk. The heads movement is controlled by close-loop feedback servo system. It is well known that dynamic behaviors of head-slider-suspension-assembly (HSA) system are of great influence on the track per inch capacity of HDD1,2. As the problem is structurally complex, it is usually investigated using experimental methods or finite element simulation models 3. Furthermore, the dual-stage servo system, that is, a conventional VCM as the primary stage and a MEMS actuator as the secondary stage for MEMS device embedded HAS, has resulted in more difficulties in predicting HDD dynamic performance. This paper presents studies of the problem using macromodeling simulation approach. It applies efficient FEM based sub-structuring synthesis (SSS)4 and fast boundary element method (BEM) approaches incorporated with system dynamics technology to investigate dynamic characteristics of MEMS actuator embedded HAS system for HDD.

  2. Cardiovascular and electrocortical markers of anger and motivation during a simulated driving task.

    PubMed

    Fairclough, Stephen H; Spiridon, Elena

    2012-05-01

    The experience of anger may have consequences for the long-term health of the individual. The psychophysiological manifestation of anger can vary in response to the motivational context of anger provocation. The current study was designed to investigate how motivational context (challenge vs. threat) influenced the cardiovascular system and frontal EEG asymmetry. 29 male participants completed a simulated driving journey with a fixed time schedule. Anger was induced by exposing participants to traffic delays at an early (challenge) and later point (threat) on the simulated route. A number of dependent variables were recorded, including 32 channels of EEG, measures of cardiovascular impedance, blood pressure and fEMG activity from the corrugator supercilii. The results indicated that traffic delays significantly increased blood pressure, heart rate, TPR and corrugator activity whilst reducing the relative level of left frontal activation in the EEG. However, there was little evidence for a consistent distinction between the early (challenge) and late (threat) introduction of traffic delay. The consequences of these findings for capturing the cardiovascular and electrocortical responses to anger induction are discussed.

  3. Time course of changes in driving simulator performance with and without treatment in patients with sleep apnoea hypopnoea syndrome

    PubMed Central

    Turkington, P; Sircar, M; Saralaya, D; Elliott, M

    2004-01-01

    Methods: Eighteen patients with severe SAHS performed a driving simulator test at baseline (before treatment) and at days 1, 3, and 7 of a 2 week CPAP trial period. CPAP was then discontinued and the patients performed three further driving simulator tests after 1, 3, and 7 days. Eighteen patients with severe SAHS acted as controls and performed the driving simulator test on seven occasions in a pattern similar to that of the treated patients. Results: Significant improvements in tracking error (p = 0.004), reaction time (p = 0.036), and the number of off road events per hour (p = 0.032) were seen in the CPAP treated group compared with the controls at 7 days. Following discontinuation of CPAP for 7 days a significant difference in driving simulator performance persisted between the two groups, but the size of the difference had reduced. Conclusion: Driving simulator performance in patients with severe SAHS improves within the first few days of starting CPAP and these improvements appear to be sustained for up to 1 week after withdrawal. Further data about the usefulness of driving simulators in predicting safe driving are needed before these results can be used in advising patients on driving. However, the data appear to suggest that driving can be safely resumed after a few days of effective CPAP treatment. PMID:14694250

  4. Observer Rated Sleepiness and Real Road Driving: An Explorative Study

    PubMed Central

    Anund, Anna; Fors, Carina; Hallvig, David; Åkerstedt, Torbjörn; Kecklund, Göran

    2013-01-01

    The aim of the present study was to explore if observer rated sleepiness (ORS) is a feasible method for quantification of driver sleepiness in field studies. Two measures of ORS were used: (1) one for behavioural signs based on facial expression, body gestures and body movements labelled B-ORS, and (2) one based on driving performance e.g. if swerving and other indicators of impaired driving occurs, labelled D-ORS. A limited number of observers sitting in the back of an experimental vehicle on a motorway about 2 hours repeatedly 3 times per day (before lunch, after lunch, at night) observed 24 participant’s sleepiness level with help of the two observer scales. At the same time the participant reported subjective sleepiness (KSS), EOG was recorded (for calculation of blink duration) and several driving measure were taken and synchronized with the reporting. Based on mixed model Anova and correlation analysis the result showed that observer ratings of sleepiness based on drivers’ impaired performance and behavioural signs are sensitive to extend the general pattern of time awake, circadian phase and time of driving. The detailed analysis of the subjective sleepiness and ORS showed weak correspondence on an individual level. Only 16% of the changes in KSS were predicted by the observer. The correlation between the observer ratings based on performance (D-ORS) and behavioural signs (B-ORS) are high (r = .588), and the B-ORS shows a moderately strong association (r = .360) with blink duration. Both ORS measures show an association (r>0.45) with KSS, whereas the association with driving performance is weak. The results show that the ORS-method detects the expected general variations in sleepy driving in field studies, however, sudden changes in driver sleepiness on a detailed level as 5 minutes is usually not detected; this holds true both when taking into account driving behaviour or driver behavioural signs. PMID:23724094

  5. "Baby on board": Reducing risk taking in adult drivers in a simulated driving game.

    PubMed

    Mammarella, Nicola; Fairfield, Beth; Di Domenico, Alberto; Di Fiore, Teresa

    2013-01-01

    Two studies examined the effects of different socio-affective factors on risk driving behaviour. In Experiment 1, 87 adult drivers we asked to play a computer-based driving game after being exposed to a series of images that depicted infants, police or neutral information (control condition). In Experiment 2 we tested a further 60 adult drivers. We found a significant effect of our manipulation on driving behaviour, with performance being significantly less risky in the infant condition than in the police and control conditions. In addition, this advantage was not simply due to variations in emotions typically associated with infant pictures. The results of this study highlight the importance of studying the role of socio-affective context when investigating factors that influence driving behaviour. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. The effects of anti-speeding advertisements on the simulated driving behaviour of young drivers.

    PubMed

    Plant, Bernice R C; Irwin, Julia D; Chekaluk, Eugene

    2017-03-01

    Recent examinations of road safety communications, including anti-speeding advertisements, have considered the differential effects of positive and negative emotional appeals on driver behaviour. However, empirical evaluations of anti-speeding messages have largely relied on measures of viewers' reported intentions to comply with speed limits and the self-reported driving behaviour of viewers post-exposure, which might not be indicative of the direct effects that these messages have on real-world driving behaviour. The current research constitutes a first empirical evaluation of different real-world anti-speeding advertisements, as measured by their effects on young drivers' speeding behaviour, using a driving simulator. Licensed drivers (N=116) aged 17-25 years completed driving measures prior to, immediately following, and 7-10days after viewing one of four social marketing advertisements. Results indicated that young drivers' average driving speeds were modestly reduced immediately after they viewed an anti-speeding advertisement that depicted social consequences for speeding and employed a positive emotional appeal when compared to an emotion-matched control advertisement; however, this effect was not found for the anti-speeding advertisement depicting a crash. Interestingly, the results based on reported intentions to reduce speeding predicted the opposite pattern of results. However, there was no evidence that the immediate changes to speeding were maintained 7-10days later, and prompts during Phase 2 did not appear to have an effect. The implications of these findings for road safety advertisements targeting young drivers are discussed.

  7. The application of quasi-steady approximation in atomic kinetics in simulation of hohlraum radiation drive

    NASA Astrophysics Data System (ADS)

    Ren, Guoli; Pei, Wenbing; Lan, Ke; Gu, Peijun; Li, Xin; Institute of Applied Physics; Computional Mathematics Team

    2011-10-01

    In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum- number(n-level) average atom model(AAM). However, the experimental frequency-dependant radiative drive differs from our n-level simulated drive, which reminds us the need of a more detailed atomic kinetics description. The orbital-quantum-number(nl-level) AAM is a natural consideration but the in-line calculation consumes much more resources. We use a new method to built up a nl-level bound electron distribution using in-line n-level calculated plasma condition (such as temperature, density, average ionization degree). We name this method ``quasi-steady approximation.'' Using the re-built nl-level bound electron distribution (Pnl) , we acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more-detailed frequency-dependant structures.

  8. Attention following traumatic brain injury: Neuropsychological and driving simulator data, and association with sleep, sleepiness, and fatigue.

    PubMed

    Beaulieu-Bonneau, Simon; Fortier-Brochu, Émilie; Ivers, Hans; Morin, Charles M

    2017-03-01

    The objectives of this study were to compare individuals with traumatic brain injury (TBI) and healthy controls on neuropsychological tests of attention and driving simulation performance, and explore their relationships with participants' characteristics, sleep, sleepiness, and fatigue. Participants were 22 adults with moderate or severe TBI (time since injury ≥ one year) and 22 matched controls. They completed three neuropsychological tests of attention, a driving simulator task, night-time polysomnographic recordings, and subjective ratings of sleepiness and fatigue. Results showed that participants with TBI exhibited poorer performance compared to controls on measures tapping speed of information processing and sustained attention, but not on selective attention measures. On the driving simulator task, a greater variability of the vehicle lateral position was observed in the TBI group. Poorer performance on specific subsets of neuropsychological variables was associated with poorer sleep continuity in the TBI group, and with a greater increase in subjective sleepiness in both groups. No significant relationship was found between cognitive performance and fatigue. These findings add to the existing evidence that speed of information processing is still impaired several years after moderate to severe TBI. Sustained attention could also be compromised. Attention seems to be associated with sleep continuity and daytime sleepiness; this interaction needs to be explored further.

  9. Detection of emergency vehicles: driver responses to advance warning in a driving simulator.

    PubMed

    Lenné, Michael G; Triggs, Thomas J; Mulvihill, Christine M; Regan, Michael A; Corben, Bruce F

    2008-02-01

    This research evaluated the effects of an advance warning device (AWD) on the safety of driver interactions with emergency vehicles (EVs). The AWD was intended to provide drivers with advance warning of an approaching on-call EV via visual and auditory warnings when the EV was within a 300- to 400-m radius. Research suggests that drivers can experience difficulty accurately detecting the distance and direction of approaching on-call EV. In-vehicle technology has not previously been explored as a means of overcoming the limitations of existing EV lights and sirens and improving driver detection of EV. An experimental study using an advanced driving simulator examined the effects of the AWD on driving performance in a range of circumstances in which real-world EV crashes and near-misses commonly occur. Each event contained a combination of scenario type (adjacent lane, turning across, car following) and warning condition (control, standard, advance). Data from 22 participants were collected, including measures of speed, braking, and visual scanning. For adjacent-lane and turning-across events, the AWD was associated primarily with reductions in mean speed. The AWD resulted in an earlier lane change to clear a path for the EV in the car-following event. The reduction in speed observed was a positive finding, given the relationship between impact speed and injury severity. Response priming emerged as the mechanism underpinning these effects. Response priming may result in safety benefits in other settings when an advisory warning is presented before the threat can be perceived.

  10. Zopiclone as positive control in studies examining the residual effects of hypnotic drugs on driving ability.

    PubMed

    Verster, Joris C; Spence, D Warren; Shahid, Azmeh; Pandi-Perumal, Seithikurippu R; Roth, Thomas

    2011-09-01

    Zopiclone (7.5 mg) is frequently used as a positive control in studies that examine the residual effects of hypnotic drugs on driving ability and related skills. This review summarizes studies examining the effects of zopiclone, and discusses its usefulness as a comparator drug for investigations of residual effects of novel sleep medication. A literature review (Pubmed and Embase) was conducted searching for studies that tested zopiclone on driving. Cross references were checked for additional papers. Eight studies utilizing the standardized on-the-road driving test consistently showed that in the morning following bedtime administration zopiclone (7.5 mg) significantly impaired driving performance. A total of 191 healthy volunteers were tested after placebo and zopiclone (7.5 mg). Meta analyses showed no significant differences in driving performance after zopiclone (7.5 mg) between adult and elderly healthy volunteers. The combined effect size (ES) and 95% confidence interval (95%CI) for healthy volunteers was 0.782 (0.620, 0.944). Relative to placebo, an average increment of 3.0 cm in Standard Deviation of Lateral Position (SDLP) was observed when treated with zopiclone (7.5 mg). This deviation was higher than the increment in SDLP reported for drivers with a blood alcohol concentration of 0.05% (+2.4 cm). Results from driving simulators and psychometric tests are consistent with the on-road driving test results. In conclusion, zopiclone (7.5 mg) is a reliable positive control, that consistently shows significant and meaningful impairment on the on-the-road driving test.

  11. Tuning and objective performance evaluation of a driving simulator to investigate tyre behaviour in on-centre handling manoeuvres

    NASA Astrophysics Data System (ADS)

    Baldoni, F.; Galante, F.; Pernetti, M.; Russo, M.; Terzo, M.; Toscano, M.

    2011-09-01

    Driving simulation aims at reproducing, within a safe and controlled environment, sensorial stimuli as close to those perceived during the actual drive as possible, in order to induce driving behaviour similar to the real one. This paper illustrates an activity carried out on the driving simulator Virtual Environment for Road Safety, bound for system performance optimisation while dealing with subjective and objective tyres evaluation in the field of on-centre manoeuvres. Such activity can be divided into two main steps. The first one, described herewith, has been focusing on platform motion algorithms tuning and has led to driving simulator objective validation within the on-centre range. Device capability of reproducing dynamics, worked out by the vehicle model, has been thoroughly examined. Simulator sensitivity to a few tyre parameters influencing vehicle lateral dynamics has been analysed too. The second step - calling for the support of experienced drivers - will pursue subjective validation.

  12. Older Adults with Mild Cognitive Impairments Show Less Driving Errors after a Multiple Sessions Simulator Training Program but Do Not Exhibit Long Term Retention

    PubMed Central

    Teasdale, Normand; Simoneau, Martin; Hudon, Lisa; Germain Robitaille, Mathieu; Moszkowicz, Thierry; Laurendeau, Denis; Bherer, Louis; Duchesne, Simon; Hudon, Carol

    2016-01-01

    The driving performance of individuals with mild cognitive impairment (MCI) is suboptimal when compared to healthy older adults. It is expected that the driving will worsen with the progression of the cognitive decline and thus, whether or not these individuals should continue to drive is a matter of debate. The aim of the study was to provide support to the claim that individuals with MCI can benefit from a training program and improve their overall driving performance in a driving simulator. Fifteen older drivers with MCI participated in five training sessions in a simulator (over a 21-day period) and in a 6-month recall session. During training, they received automated auditory feedback on their performance when an error was noted about various maneuvers known to be suboptimal in MCI individuals (for instance, weaving, omitting to indicate a lane change, to verify a blind spot, or to engage in a visual search before crossing an intersection). The number of errors was compiled for eight different maneuvers for all sessions. For the initial five sessions, a gradual and significant decrease in the number of errors was observed, indicating learning and safer driving. The level of performance, however, was not maintained at the 6-month recall session. Nevertheless, the initial learning observed opens up possibilities to undertake more regular interventions to maintain driving skills and safe driving in MCI individuals. PMID:28082883

  13. Older Adults with Mild Cognitive Impairments Show Less Driving Errors after a Multiple Sessions Simulator Training Program but Do Not Exhibit Long Term Retention.

    PubMed

    Teasdale, Normand; Simoneau, Martin; Hudon, Lisa; Germain Robitaille, Mathieu; Moszkowicz, Thierry; Laurendeau, Denis; Bherer, Louis; Duchesne, Simon; Hudon, Carol

    2016-01-01

    The driving performance of individuals with mild cognitive impairment (MCI) is suboptimal when compared to healthy older adults. It is expected that the driving will worsen with the progression of the cognitive decline and thus, whether or not these individuals should continue to drive is a matter of debate. The aim of the study was to provide support to the claim that individuals with MCI can benefit from a training program and improve their overall driving performance in a driving simulator. Fifteen older drivers with MCI participated in five training sessions in a simulator (over a 21-day period) and in a 6-month recall session. During training, they received automated auditory feedback on their performance when an error was noted about various maneuvers known to be suboptimal in MCI individuals (for instance, weaving, omitting to indicate a lane change, to verify a blind spot, or to engage in a visual search before crossing an intersection). The number of errors was compiled for eight different maneuvers for all sessions. For the initial five sessions, a gradual and significant decrease in the number of errors was observed, indicating learning and safer driving. The level of performance, however, was not maintained at the 6-month recall session. Nevertheless, the initial learning observed opens up possibilities to undertake more regular interventions to maintain driving skills and safe driving in MCI individuals.

  14. The immediate effects of glare and electrochromic glare-reducing mirrors in simulated truck driving.

    PubMed

    Ranney, T A; Simmons, L A; Masalonis, A J

    2000-01-01

    In this experiment 12 experienced truck drivers drove a fixed-base driving simulator for three 8-h sessions under simulated nighttime driving conditions. Sessions included (a) no glare, (b) intermittent glare presented in the exterior rearview mirrors to simulate following vehicles, and (c) intermittent glare with electrochromic glare reduction. The driving task combined vehicle control on straight and curved road segments with detection of pedestrians appearing alongside the road and targets appearing in the rearview mirrors. The presence of glare slowed detection of pedestrians and, to a lesser extent, slowed the detection of targets appearing in mirrors. Glare was also associated with increased lane position variability, reduced speed on curves, and, most consistently, increased steering variability. We found only meager evidence that electrochromic glare reduction improved target detection performance and no evidence that glare reduction improved vehicle control, despite the fact that participants consistently voiced positive preferences for glare reduction. The results will aid decision making that requires incorporation of the benefits of electrochromic glare-reducing mirrors.

  15. Test Results from a Direct Drive Gas Reactor Simulator Coupled to a Brayton Power Conversion Unit

    NASA Technical Reports Server (NTRS)

    Hervol, David S.; Briggs, Maxwell H.; Owen, Albert K.; Bragg-Sitton, Shannon M.; Godfroy, Thomas J.

    2010-01-01

    Component level testing of power conversion units proposed for use in fission surface power systems has typically been done using relatively simple electric heaters for thermal input. These heaters do not adequately represent the geometry or response of proposed reactors. As testing of fission surface power systems transitions from the component level to the system level it becomes necessary to more accurately replicate these reactors using reactor simulators. The Direct Drive Gas-Brayton Power Conversion Unit test activity at the NASA Glenn Research Center integrates a reactor simulator with an existing Brayton test rig. The response of the reactor simulator to a change in Brayton shaft speed is shown as well as the response of the Brayton to an insertion of reactivity, corresponding to a drum reconfiguration. The lessons learned from these tests can be used to improve the design of future reactor simulators which can be used in system level fission surface power tests.

  16. Effect of audio in-vehicle red light-running warning message on driving behavior based on a driving simulator experiment.

    PubMed

    Yan, Xuedong; Liu, Yang; Xu, Yongcun

    2015-01-01

    Drivers' incorrect decisions of crossing signalized intersections at the onset of the yellow change may lead to red light running (RLR), and RLR crashes result in substantial numbers of severe injuries and property damage. In recent years, some Intelligent Transport System (ITS) concepts have focused on reducing RLR by alerting drivers that they are about to violate the signal. The objective of this study is to conduct an experimental investigation on the effectiveness of the red light violation warning system using a voice message. In this study, the prototype concept of the RLR audio warning system was modeled and tested in a high-fidelity driving simulator. According to the concept, when a vehicle is approaching an intersection at the onset of yellow and the time to the intersection is longer than the yellow interval, the in-vehicle warning system can activate the following audio message "The red light is impending. Please decelerate!" The intent of the warning design is to encourage drivers who cannot clear an intersection during the yellow change interval to stop at the intersection. The experimental results showed that the warning message could decrease red light running violations by 84.3 percent. Based on the logistic regression analyses, drivers without a warning were about 86 times more likely to make go decisions at the onset of yellow and about 15 times more likely to run red lights than those with a warning. Additionally, it was found that the audio warning message could significantly reduce RLR severity because the RLR drivers' red-entry times without a warning were longer than those with a warning. This driving simulator study showed a promising effect of the audio in-vehicle warning message on reducing RLR violations and crashes. It is worthwhile to further develop the proposed technology in field applications.

  17. Mirage events & driver haptic steering alerts in a motion-base driving simulator: A method for selecting an optimal HMI.

    PubMed

    Talamonti, Walter; Tijerina, Louis; Blommer, Mike; Swaminathan, Radhakrishnan; Curry, Reates; Ellis, R Darin

    2017-11-01

    This paper describes a new method, a 'mirage scenario,' to support formative evaluation of driver alerting or warning displays for manual and automated driving. This method provides driving contexts (e.g., various Times-To-Collision (TTCs) to a lead vehicle) briefly presented and then removed. In the present study, during each mirage event, a haptic steering display was evaluated. This haptic display indicated a steering response may be initiated to drive around an obstacle ahead. A motion-base simulator was used in a 32-participant study to present vehicle motion cues similar to the actual application. Surprise was neither present nor of concern, as it would be for a summative evaluation of a forward collision warning system. Furthermore, no collision avoidance maneuvers were performed, thereby reducing the risk of simulator sickness. This paper illustrates the mirage scenario procedures, the rating methods and definitions used with the mirage scenario, and analysis of the ratings obtained, together with a multi-attribute utility theory (MAUT) approach to evaluate and select among alternative designs for future summative evaluation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. What Drives Teacher Engagement: A Study of Different Age Cohorts

    ERIC Educational Resources Information Center

    Guglielmi, Dina; Bruni, Ilaria; Simbula, Silvia; Fraccaroli, Franco; Depolo, Marco

    2016-01-01

    Despite the growing body of research on work engagement, little is known about what drives work engagement among different age cohorts. This study aims to investigate whether engagement varies across age cohorts and examines the job resources that foster teacher engagement. A questionnaire was distributed to 537 teachers who were employed in…

  19. Experiments and simulation of thermal behaviors of the dual-drive servo feed system

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Mei, Xuesong; Feng, Bin; Zhao, Liang; Ma, Chi; Shi, Hu

    2015-01-01

    The machine tool equipped with the dual-drive servo feed system could realize high feed speed as well as sharp precision. Currently, there is no report about the thermal behaviors of the dual-drive machine, and the current research of the thermal characteristics of machines mainly focuses on steady simulation. To explore the influence of thermal characterizations on the precision of a jib boring machine assembled dual-drive feed system, the thermal equilibrium tests and the research on thermal-mechanical transient behaviors are carried out. A laser interferometer, infrared thermography and a temperature-displacement acquisition system are applied to measure the temperature distribution and thermal deformation at different feed speeds. Subsequently, the finite element method (FEM) is used to analyze the transient thermal behaviors of the boring machine. The complex boundary conditions, such as heat sources and convective heat transfer coefficient, are calculated. Finally, transient variances in temperatures and deformations are compared with the measured values, and the errors between the measurement and the simulation of the temperature and the thermal error are 2 °C and 2.5 μm, respectively. The researching results demonstrate that the FEM model can predict the thermal error and temperature distribution very well under specified operating condition. Moreover, the uneven temperature gradient is due to the asynchronous dual-drive structure that results in thermal deformation. Additionally, the positioning accuracy decreases as the measured point became further away from the motor, and the thermal error and equilibrium period both increase with feed speeds. The research proposes a systematical method to measure and simulate the boring machine transient thermal behaviors.

  20. Experimental evaluation of hybrid vehicle fuel economy and pollutant emissions over real-world simulation driving cycles

    NASA Astrophysics Data System (ADS)

    Fontaras, Georgios; Pistikopoulos, Panayotis; Samaras, Zissis

    2008-06-01

    The reduction of transport-generated CO2 emissions is currently a problem of global interest. Hybrid electric vehicles (HEVs) are considered as one promising technological solution for limiting transport-generated greenhouse gas emissions. Currently, the number of HEVs in the market remains limited, but this picture will change in the years to come as HEVs are expected to pave the way for cleaner technologies in transport. In this paper, results are presented regarding fuel economy and pollutant emissions measurements of two hybrid electric production vehicles. The measurements were conducted on a Prius II and a Honda Civic IMA using both the European legislated driving cycle (New European Driving Cycle, NEDC) and real-world simulation driving cycles (Artemis). In addition to the emissions measurements, other vehicle-operating parameters were studied in an effort to better quantify the maximum CO2 reduction potential. Data from real-world operation of a Prius II vehicle were also used in the evaluation. Results indicate that in most cases both vehicles present improved energy efficiency and pollutant emissions compared to conventional cars. The fuel economy benefit of the two HEVs peaked under urban driving conditions where reductions of 60% and 40% were observed, respectively. Over higher speeds the difference in fuel economy was lower, reaching that of conventional diesel at 95 km h-1. The effect of ambient temperature on fuel consumption was also quantified. It is concluded that urban operation benefits the most of hybrid technology, leading to important fuel savings and urban air quality improvement.

  1. Simulation of Electrostatic Actuation in Interdigitated Comb Drive MEMS Resonator for Energy Harvester Applications

    NASA Astrophysics Data System (ADS)

    Sathya, S.; Pavithra, M.; Muruganand, S.

    2016-09-01

    This paper presents an actuation mechanism based on the interdigitated comb drive MEMS resonator. The important role of that device is to establish MEMS resonators for the second order systems. Comb drive model is one of the basic model which uses the principle of electrostatic and force can be generated for the capacitive sensors. This work is done by overlapping movable and fixed comb fingers which produces an energy. The specific range of the polyimide material properties of young's modulus of 3.1GPa and density of 1300 Kg/m3. Results are shown in the structural domain performance of a lateral motion which corresponds to the applying voltage between the interdigitated comb fingers. It has laterally driven about 40pm with driving voltage. Also the resonance frequency 24Hz and 15Hz with high quality factors are depending on the spring length 260pm and 360pm and structure thickness of 2μm and 5 μm. Here Finite element method (FEM) is used to simulate the various physics scenario and it is designed as two dimensional structure multiphysics domain. The prototype of comb drive MEMS resonator has been suitable for energy harvesting system applications.

  2. Driving with hemianopia: IV. Head scanning and detection at intersections in a simulator.

    PubMed

    Bowers, Alex R; Ananyev, Egor; Mandel, Aaron J; Goldstein, Robert B; Peli, Eli

    2014-03-13

    Using a driving simulator, we examined the effects of homonymous hemianopia (HH) on head scanning behaviors at intersections and evaluated the role of inadequate head scanning in detection failures. Fourteen people with complete HH and without cognitive decline or visual neglect and 12 normally sighted (NV) current drivers participated. They drove in an urban environment following predetermined routes, which included multiple intersections. Head scanning behaviors were quantified at T-intersections (n = 32) with a stop or yield sign. Participants also performed a pedestrian detection task. The relationship between head scanning and detection was examined at 10 intersections. For HH drivers, the first scan was more likely to be toward the blind than the seeing hemifield. They also made a greater proportion of head scans overall to the blind side than did the NV drivers to the corresponding side (P = 0.003). However, head scan magnitudes of HH drivers were smaller than those of the NV group (P < 0.001). Drivers with HH had impaired detection of blind-side pedestrians due either to not scanning in the direction of the pedestrian or to an insufficient scan magnitude (left HH detected only 46% and right HH 8% at the extreme left and right of the intersection, respectively). Drivers with HH demonstrated compensatory head scan patterns, but not scan magnitudes. Inadequate scanning resulted in blind-side detection failures, which might place HH drivers at increased risk for collisions at intersections. Scanning training tailored to specific problem areas identified in this study might be beneficial.

  3. Age Differences in Visual-Auditory Self-Motion Perception during a Simulated Driving Task

    PubMed Central

    Ramkhalawansingh, Robert; Keshavarz, Behrang; Haycock, Bruce; Shahab, Saba; Campos, Jennifer L.

    2016-01-01

    Recent evidence suggests that visual-auditory cue integration may change as a function of age such that integration is heightened among older adults. Our goal was to determine whether these changes in multisensory integration are also observed in the context of self-motion perception under realistic task constraints. Thus, we developed a simulated driving paradigm in which we provided older and younger adults with visual motion cues (i.e., optic flow) and systematically manipulated the presence or absence of congruent auditory cues to self-motion (i.e., engine, tire, and wind sounds). Results demonstrated that the presence or absence of congruent auditory input had different effects on older and younger adults. Both age groups demonstrated a reduction in speed variability when auditory cues were present compared to when they were absent, but older adults demonstrated a proportionally greater reduction in speed variability under combined sensory conditions. These results are consistent with evidence indicating that multisensory integration is heightened in older adults. Importantly, this study is the first to provide evidence to suggest that age differences in multisensory integration may generalize from simple stimulus detection tasks to the integration of the more complex and dynamic visual and auditory cues that are experienced during self-motion. PMID:27199829

  4. Spine Posture and Discomfort During Prolonged Simulated Driving With Self-Selected Lumbar Support Prominence.

    PubMed

    De Carvalho, Diana E; Callaghan, Jack P

    2015-09-01

    We examined magnitude preference, subjective discomfort, and spine posture during prolonged simulated driving with a self-selected amount of lumbar support. The general use of lumbar supports has been associated with decreased reports of low-back pain during driving exposures; however, minimal data exist regarding occupant magnitude preference. Participants chose between five discrete levels of lumbar support (0-4 cm). Time-varying postural and discomfort responses were then monitored throughout 2 hr of simulated driving. There were no significant effects of gender or time on posture. Women preferred larger amounts of support than men (3.25 cm ± 0.71 and 2.56 cm ± 0.88, respectively, p = .048). All participants exhibited significant increases (p = .003) in pelvic discomfort throughout the 2-hr trial regardless of the level of support chosen. Discomfort related to various aspects of the lumbar support increased significantly over time. Retrospectively, no participants desired a setting beyond 4 cm, and the majority of respondents indicate had they been able to change their initial selection, they would choose a setting between 2 and 3 cm. The results suggest that occupants would prefer increasing the excursion capability of automobile lumbar supports beyond 2 cm. Excursion capability and adjustability of automobile lumbar supports are important features to better meet end-user preference and to reducing lumbar flexion in sitting. © 2015, Human Factors and Ergonomics Society.

  5. Driving simulation in the clinic: testing visual exploratory behavior in daily life activities in patients with visual field defects.

    PubMed

    Hamel, Johanna; Kraft, Antje; Ohl, Sven; De Beukelaer, Sophie; Audebert, Heinrich J; Brandt, Stephan A

    2012-09-18

    Patients suffering from homonymous hemianopia after infarction of the posterior cerebral artery (PCA) report different degrees of constraint in daily life, despite similar visual deficits. We assume this could be due to variable development of compensatory strategies such as altered visual scanning behavior. Scanning compensatory therapy (SCT) is studied as part of the visual training after infarction next to vision restoration therapy. SCT consists of learning to make larger eye movements into the blind field enlarging the visual field of search, which has been proven to be the most useful strategy(1), not only in natural search tasks but also in mastering daily life activities(2). Nevertheless, in clinical routine it is difficult to identify individual levels and training effects of compensatory behavior, since it requires measurement of eye movements in a head unrestrained condition. Studies demonstrated that unrestrained head movements alter the visual exploratory behavior compared to a head-restrained laboratory condition(3). Martin et al.(4) and Hayhoe et al.(5) showed that behavior demonstrated in a laboratory setting cannot be assigned easily to a natural condition. Hence, our goal was to develop a study set-up which uncovers different compensatory oculomotor strategies quickly in a realistic testing situation: Patients are tested in the clinical environment in a driving simulator. SILAB software (Wuerzburg Institute for Traffic Sciences GmbH (WIVW)) was used to program driving scenarios of varying complexity and recording the driver's performance. The software was combined with a head mounted infrared video pupil tracker, recording head- and eye-movements (EyeSeeCam, University of Munich Hospital, Clinical Neurosciences). The positioning of the patient in the driving simulator and the positioning, adjustment and calibration of the camera is demonstrated. Typical performances of a patient with and without compensatory strategy and a healthy control are

  6. Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects

    PubMed Central

    Hamel, Johanna; Kraft, Antje; Ohl, Sven; De Beukelaer, Sophie; Audebert, Heinrich J.; Brandt, Stephan A.

    2012-01-01

    Patients suffering from homonymous hemianopia after infarction of the posterior cerebral artery (PCA) report different degrees of constraint in daily life, despite similar visual deficits. We assume this could be due to variable development of compensatory strategies such as altered visual scanning behavior. Scanning compensatory therapy (SCT) is studied as part of the visual training after infarction next to vision restoration therapy. SCT consists of learning to make larger eye movements into the blind field enlarging the visual field of search, which has been proven to be the most useful strategy1, not only in natural search tasks but also in mastering daily life activities2. Nevertheless, in clinical routine it is difficult to identify individual levels and training effects of compensatory behavior, since it requires measurement of eye movements in a head unrestrained condition. Studies demonstrated that unrestrained head movements alter the visual exploratory behavior compared to a head-restrained laboratory condition3. Martin et al.4 and Hayhoe et al.5 showed that behavior demonstrated in a laboratory setting cannot be assigned easily to a natural condition. Hence, our goal was to develop a study set-up which uncovers different compensatory oculomotor strategies quickly in a realistic testing situation: Patients are tested in the clinical environment in a driving simulator. SILAB software (Wuerzburg Institute for Traffic Sciences GmbH (WIVW)) was used to program driving scenarios of varying complexity and recording the driver's performance. The software was combined with a head mounted infrared video pupil tracker, recording head- and eye-movements (EyeSeeCam, University of Munich Hospital, Clinical Neurosciences). The positioning of the patient in the driving simulator and the positioning, adjustment and calibration of the camera is demonstrated. Typical performances of a patient with and without compensatory strategy and a healthy control are illustrated in

  7. Simulation of steady-state diffusion: driving force ensured by dual control volumes or local equilibrium Monte Carlo.

    PubMed

    Ható, Zoltán; Boda, Dezső; Kristóf, Tamás

    2012-08-07

    We provide a systematic comparative analysis of various simulation methods for studying steady-state diffusive transport of molecular systems. The methods differ in two respects: (1) the actual method with which the dynamics of the system is handled can be a direct simulation technique [molecular dynamics (MD) and dynamic Monte Carlo (DMC)] or can be an indirect transport equation [the Nernst-Planck (NP) equation], while (2) the driving force of the steady-state transport can be maintained with control cells on the two sides of the transport region [dual control volume (DCV) technique] or it can be maintained in the whole simulation domain with the local equilibrium Monte Carlo (LEMC) technique, where the space is divided into small subvolumes, different chemical potentials are assigned to each, and grand canonical Monte Carlo simulations are performed for them separately. The various combinations of the transport-methods with the driving-force methods have advantages and disadvantages. The MD+DCV and DMC+DCV methods are widely used to study membrane transport. The LEMC method has been introduced with the NP+LEMC technique, which was proved to be a fast, but somewhat empirical method to study diffusion [D. Boda and D. Gillespie, J. Chem. Theor. Comput. 8, 824 (2012)]. In this paper, we introduce the DMC+LEMC method and show that the resulting DMC+LEMC technique has the advantage over the DMC+DCV method that it provides better sampling for the flux, while it has the advantage over the NP+LEMC method that it simulates dynamics directly instead of hiding it in an external adjustable parameter, the diffusion coefficient. The information gained from the DMC+LEMC simulation can be used to construct diffusion coefficient profiles for the NP+LEMC calculations, so a simultaneous application of the two methods is advantageous.

  8. Increasing following headway with prompts, goal setting, and feedback in a driving simulator.

    PubMed

    Arnold, Michelle L; Van Houten, Ron

    2011-01-01

    We evaluated the effects of prompting, goal setting, and feedback on following headway of young drivers in a simulated driving environment and assessed whether changes produced in following headway were associated with reductions in hard braking when drivers were and were not using cell phones. Participants were 4 university students. During baseline, drivers spent half of the time talking on cell phones while driving. At the start of the intervention, drivers were prompted to increase following headway while on the cell phones and were provided a specific target for following headway. Drivers were given feedback on increasing following headway when on cell phones at the end of each session. The intervention package was associated with an increase in following headway and a decrease in hard braking when participants were on and off the cell phones. Cell phone use did not affect any of the measures.

  9. INCREASING FOLLOWING HEADWAY WITH PROMPTS, GOAL SETTING, AND FEEDBACK IN A DRIVING SIMULATOR

    PubMed Central

    Arnold, Michelle L; Van Houten, Ron

    2011-01-01

    We evaluated the effects of prompting, goal setting, and feedback on following headway of young drivers in a simulated driving environment and assessed whether changes produced in following headway were associated with reductions in hard braking when drivers were and were not using cell phones. Participants were 4 university students. During baseline, drivers spent half of the time talking on cell phones while driving. At the start of the intervention, drivers were prompted to increase following headway while on the cell phones and were provided a specific target for following headway. Drivers were given feedback on increasing following headway when on cell phones at the end of each session. The intervention package was associated with an increase in following headway and a decrease in hard braking when participants were on and off the cell phones. Cell phone use did not affect any of the measures. PMID:21709782

  10. Quasi-spherical direct drive fusion simulations for the Z machine and future accelerators.

    SciTech Connect

    VanDevender, J. Pace; McDaniel, Dillon Heirman; Roderick, Norman Frederick; Nash, Thomas J.

    2007-11-01

    We explored the potential of Quasi-Spherical Direct Drive (QSDD) to reduce the cost and risk of a future fusion driver for Inertial Confinement Fusion (ICF) and to produce megajoule thermonuclear yield on the renovated Z Machine with a pulse shortening Magnetically Insulated Current Amplifier (MICA). Analytic relationships for constant implosion velocity and constant pusher stability have been derived and show that the required current scales as the implosion time. Therefore, a MICA is necessary to drive QSDD capsules with hot-spot ignition on Z. We have optimized the LASNEX parameters for QSDD with realistic walls and mitigated many of the risks. Although the mix-degraded 1D yield is computed to be {approx}30 MJ on Z, unmitigated wall expansion under the > 100 gigabar pressure just before burn prevents ignition in the 2D simulations. A squeezer system of adjacent implosions may mitigate the wall expansion and permit the plasma to burn.

  11. SBS in Long-Scale-Length Plasmas for Direct-Drive ICF: Comparing Experiments with Simulations

    NASA Astrophysics Data System (ADS)

    Seka, W.; Myatt, J.; Maximov, A. V.; Short, R. W.; Craxton, R. S.; Regan, S. P.; Meyerhofer, D. D.; Stoeckl, C.; Yaakobi, B.

    2002-11-01

    Single- and multiple-beam SBS experiments will be compared to detailed simulations for plasmas representing direct-drive NIF conditions. The SBS spectra exhibit red- and blue-shifted features. The blue-shifted component is clearly identified with SBS in a flat velocity gradient that rapidly moves to higher expansion velocities. This feature can be reduced or suppressed by beam-smoothing techniques in both the experiments and simulations. The red-shifted spectrum originates near the critical density; it arises from EM seeding and is not reduced by beam smoothing. The agreement between experimental data and simulations now allows for more-confident extrapolation to other plasma conditions. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  12. Traffic calming along rural highways crossing small urban communities: driving simulator experiment.

    PubMed

    Galante, Francesco; Mauriello, Filomena; Montella, Alfonso; Pernetti, Mariano; Aria, Massimo; D'Ambrosio, Antonio

    2010-11-01

    The paper investigated drivers' speed behaviour in a section of a rural highway crossing a small urban community in the existing scenario without any traffic calming device and in two different design scenarios with traffic calming in the urban community. Two gateways and four integrative traffic calming devices along the route within the urban area were tested. The gateways were aimed at slowing down the vehicles entering in the built-up area, while the traffic calming devices were aimed at complementing the gateway effect inside the built-up area. Two design options were tested: first option (alt1) is a combination of low cost measures, whereas the second option (alt2) is more expensive as includes a chicane and requires land acquisition. Drivers' behaviour was investigated by means of a driving simulator experiment. The VERA dynamic-driving simulator operating at the TEST Road Safety Laboratory located in Naples (Italy) was used. Simulation results were validated by the comparison of speed behaviour in the real world and in the driving simulator, in the scenario without traffic calming. Analysis of the driving simulator experiment results was performed using two different approaches: (a) explorative description of data by cluster analysis; (b) inferential procedures about population using statistical tests. Cluster analysis was carried out in order to test if the drivers' speed behaviour in the different design alternatives was substantially different. Statistical tests were performed in order to verify if speeds in specific sections were significantly different. Cluster analysis looked at speed profiles, whereas statistical tests looked at speed data in specific points. The obtained results showed a different behaviour of drivers approaching the urban community in the existing scenario and in the design scenarios. In the south direction, mean speed reduction ranging between 16 and 17 km/h, with 5% level of significance, was observed. In the north direction

  13. Observational study of the extent of driving while suspended for alcohol impaired driving.

    PubMed

    McCartt, A T; Geary, L L; Berning, A

    2003-06-01

    To determine the proportion of first time driving while alcohol impaired (DWI) offenders who drive while their driver's license is suspended. Systematic, unobtrusive observations were conducted by surveillance professionals from Pinkerton Investigative Services, Inc, of first time offenders in the City of Milwaukee, Wisconsin, and Bergen County, New Jersey. Observations included two four hour periods during suspension (one weekday morning, one Friday/Saturday evening) and two four hour periods after license reinstatement (matched by day of week and time of day). Focus groups of first time offenders were conducted in each site. New Jersey laws pertaining to license suspension for DWI and driving while suspended are stronger than Wisconsin laws. 93 recently convicted first time DWI offenders (57 in Milwaukee and 36 in Bergen County). Proportion of subjects observed driving during suspension and after license reinstatement, with reference to all subjects and subjects observed traveling by any means. Of subjects observed traveling while suspended, 88% of Milwaukee subjects compared with 36% of Bergen County subjects drove. Five percent of Milwaukee subjects and 78% of Bergen County subjects reinstated their driver's license. Bergen County subjects were significantly more likely to drive after reinstatement (54%) than during suspension (25%). Prevalence of driving while suspended among first time offenders is high and can vary substantially between jurisdictions. However, the license suspension can have a positive impact on the driving patterns of offenders during suspension, relative to after license reinstatement. Lower prevalence of driving while suspended in New Jersey may partly be attributable to that state's tougher laws.

  14. The effect of billboard design specifications on driving: A pilot study.

    PubMed

    Marciano, Hadas; Setter, Pe'erly

    2017-07-01

    Decades of research on the effects of advertising billboards on road accident rates, driver performance, and driver visual scanning behavior, has produced no conclusive findings. We suggest that road safety researchers should shift their focus and attempt to identify the billboard characteristics that are most distracting to drivers. This line of research may produce concrete guidelines for permissible billboards that would be likely to reduce the influence of the billboards on road safety. The current study is a first step towards this end. A pool of 161 photos of real advertising billboards was used as stimuli within a triple task paradigm designed to simulate certain components of driving. Each trial consisted of one ongoing tracking task accompanied by two additional concurrent tasks: (1) billboard observation task; and (2) circle color change identification task. Five clusters of billboards, identified by conducting a cluster analysis of their graphic content, were used as a within variable in one-way ANOVAs conducted on performance level data collected from the multiple tasks. Cluster 5, labeled Loaded Billboards, yielded significantly deteriorated performance on the tracking task. Cluster 4, labeled Graphical Billboards, yielded deteriorated performance primarily on the color change identification task. Cluster 3, labeled Minimal Billboards, had no effect on any of these tasks. We strongly recommend that these clusters be systematically explored in experiments involving additional real driving settings, such as driving simulators and field studies. This will enable validation of the current results and help incorporate them into real driving situations. Copyright © 2017. Published by Elsevier Ltd.

  15. [Instantaneous emission simulation for light-duty diesel vehicle with different driving cycles by CMEM model].

    PubMed

    Dai, Pu; Chen, Chang-Hong; Huang, Cheng; Li, Li; Jia, Ji-Hong; Dong, Yan-Qiang

    2009-05-15

    CMEM model for calculating time based instantaneous emission from light duty diesel vehicle and its input parameters were introduced. On-board test data were used to validate the simulation results. The relative error of THC, CO, and NOx are 14.2%, 3.7% and 32.7%, respectively, while the correlation coefficients reach 0.73, 0.72 and 0.87. The instantaneous emissions of the light duty diesel vehicle simulated by CMEM model are strongly coherent with the transient driving cycle in Shanghai. The simulation of instantaneous emissions and fuel economy under the ECE-15 cycle, FTP cycle, Japan 10-15 cycle and the cycle of shanghai arterial road show that the instantaneous emissions decline with the increase of the vehicle speed, especially from 0-10 km x h(-1) to 10-20 km x h(-1). The acceleration process dominated the whole emissions, which contributes over 30% of the total emission, and sometimes it even reaches over 70%. The contributions of shanghai arterial road for idle condition are 40% and 30%, emission factors of CO are 1.3, 1.5 and 1.4 times of ECE-15 cycle, FTP cycle, Japan 10-15 cycle respectively; THC are respectively 1.5, 2.1 and 1.9 times of above cycles; and emission factors of NOx are respectively 1.2, 1.3 and 1.3 times of ECE-15 cycle, FTP cycle and Japan 10-15 cycle. The fuel economy of the light-duty diesel car on shanghai arterial road is the worst, which is 9.56 km x L(-1). The driving cycles used on abroad can not reflect the actual driving conditions in China.

  16. Simulation and assessment of ion kinetic effects in a direct-drive capsule implosion experiment

    NASA Astrophysics Data System (ADS)

    Le, A.; Kwan, T. J. T.; Schmitt, M. J.; Herrmann, H. W.; Batha, S. H.

    2016-10-01

    The first simulations employing a kinetic treatment of both fuel and shell ions to model inertial confinement fusion experiments are presented, including results showing the importance of kinetic physics processes in altering fusion burn. A pair of direct drive capsule implosions performed at the OMEGA facility with two different gas fills of deuterium, tritium, and helium-3 are analyzed. During implosion shock convergence, highly non-Maxwellian ion velocity distributions and separations in the density and temperature amongst the ion species are observed. Diffusion of fuel into the capsule shell is identified as a principal process that degrades fusion burn performance.

  17. Simulation and assessment of ion kinetic effects in a direct-drive capsule implosion experiment

    SciTech Connect

    Le, Ari Yitzchak; Kwan, Thomas J. T.; Schmitt, Mark J.; Herrmann, Hans W.; Batha, Steven H.

    2016-10-24

    The first simulations employing a kinetic treatment of both fuel and shell ions to model inertial confinement fusion experiments are presented, including results showing the importance of kinetic physics processes in altering fusion burn. A pair of direct drive capsule implosions performed at the OMEGA facility with two different gas fills of deuterium, tritium, and helium-3 are analyzed. During implosion shock convergence, highly non-Maxwellian ion velocity distributions and separations in the density and temperature amongst the ion species are observed. Finally, diffusion of fuel into the capsule shell is identified as a principal process that degrades fusion burn performance.

  18. Empirical Study of Drive-by-Download Spyware

    DTIC Science & Technology

    2006-03-01

    Empirical Study of Drive-by-Download Spyware Mark Barwinski, Cynthia Irvine and Tim Levin Naval Postgraduate School, Monterey, USA markbarwinski...hotmail.com; irvine@nps.edu; levin@nps.edu; Abstract: The ability of spyware to circumvent common security practices, surreptitiously exporting...computing environments. While it is the common perception that spyware infection is the result of high risk Internet surfing behavior, our research

  19. Light-Duty Drive Cycle Simulations of Diesel Engine-Out Exhaust Properties for an RCCI-Enabled Vehicle

    SciTech Connect

    Gao, Zhiming; Curran, Scott; Daw, C Stuart; Wagner, Robert M

    2013-01-01

    In-cylinder blending of gasoline and diesel fuels to achieve low-temperature reactivity controlled compression ignition (RCCI) can reduce NOx and PM emissions while maintaining or improving brake thermal efficiency compared to conventional diesel combustion (CDC). Moreover, the dual-fueling RCCI is able to achieve these benefits by tailoring combustion reactivity over a wider range of engine operation than is possible with a single fuel. However, the currently demonstrated range of stable RCCI combustion just covers a portion of the engine speed-load range required in several light-duty drive cycles. This means that engines must switch from RCCI to CDC when speed and load fall outside of the stable RCCI range. In this study we investigated the impact of RCCI as it has recently been demonstrated on practical engine-out exhaust temperature and emissions by simulating a multi-mode RCCI-enabled vehicle operating over two urban and two highway driving cycles. To implement our simulations, we employed experimental engine maps for a multi-mode RCCI/CDC engine combined with a standard mid-size, automatic transmission, passenger vehicle in the Autonomie vehicle simulation platform. Our results include both detailed transient and cycle-averaged engine exhaust temperature and emissions for each case, and we note the potential implications of the modified exhaust properties on catalytic emissions control and utilization of waste heat recovery on future RCCI-enabled vehicles.

  20. The application of quasi-steady approximation in atomic kinetics in simulation of hohlraum radiation drive

    NASA Astrophysics Data System (ADS)

    Ren, Guoli; Pei, Wenbing; Lan, Ke; Li, Xin; Hohlraum Physics Team

    2014-10-01

    In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum-number (n-level) average atom model (AAM) in NLTE plasma description. The more sophisticated atomic kinetics description is better choice, but the in-line calculation consumes much more resource. By distinguishing the much more fast bound-bound atomic processes from the relative slow bound-free atomic processes, we found a method to built up a bound electron distribution (n-level or nl-level) using in-line n-level calculated plasma condition (such as temperature, density, average ionization degree). We name this method ``quasi-steady approximation.'' Using this method and the plasma condition calculated under n-level, we re-build the nl-level bound electron distribution (Pnl), and acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more-detailed frequency-dependant structures. Also we use this method in the benchmark gold sphere experiment, the constructed nl-level radiation drive resembles the experimental results and DCA results, while the n-level raditation does not.

  1. Development of a night-driving simulator concept for night vision image-intensification device training

    NASA Astrophysics Data System (ADS)

    Ruffner, John W.; Piccione, Dino; Woodward, Kim G.

    1997-06-01

    The use of night vision devices (NVDs) by US Army foot soldiers, aviator,s and drivers of combat and tactical wheeled vehicles has enhanced operations at night by allowing increased mobility and potentially safer operations. With this increased capability in the night environment has come an increased exposure to the hazards of that environment and the risks that the command structure must manage and balance with mission requirements. Numerous vehicular accidents have occurred during night filed exercises involving drivers wearing image intensification (I2) systems. These accidents can frequently be attributed to perceptual problems experienced by the drivers. Performance with NVDs generally increases with practice and experience. However, there is little formal training provided in night driving skills and few opportunities to practice these skills under realistic conditions. This paper reports the approach and preliminary result of an effort to define and demonstrate a low-cost night driving simulator concept for training night driving skills with I2 devices and to identify and evaluate the techniques and resources that are available for implementing this approach.

  2. Crash barriers and driver behavior: a simulator study.

    PubMed

    Antonson, Hans; Ahlström, Christer; Wiklund, Mats; Blomqvist, Göran; Mårdh, Selina

    2013-01-01

    The study examines how drivers experience a conventional W-beam guardrail (metal crash barrier) along both sides of narrow versus wider roads (single carriageway with 2 lanes) in terms of stress, feelings, and driving patterns and whether subjective experience concurs with the actual driving patterns captured by the quantitative data. The study used different methods to capture data, including the VTI Driving Simulator III (speed and lateral vehicle position) in conjunction with electrocardiogram (ECG) data on heart rate variability (HRV) and questionnaires (oral during driving and written after driving). Eighteen participants--8 men and 10 women--were recruited for the simulator study and the simulator road section was 10 km long. Driving speeds increased slightly on the wider road and on the road with a crash barrier, and the lateral driving position was nearer to the road center on the narrower road and on the road with a crash barrier. The HRV data did not indicate that participants experienced greater stress due to road width or due to the presence of a crash barrier. Participant experience captured in the oral questionnaires suggested that road width did not affect driver stress or driving patterns; however, the written questionnaire results supported the simulator data, indicating that a wider road led to increased speed. None of the participants felt that crash barriers made them feel calmer. We believe that there is a possibility that the increased speed on roads with crash barriers may be explained by drivers' sense of increased security. This study demonstrates that an experimental design including experience-based data captured using both a simulator and questionnaires is productive. It also demonstrates that driving simulators can be used to study road features such as crash barriers. It seems more than likely that features such as street lamps, signs, and landscape objects could be tested in this way.

  3. Effect of sleep deprivation and driving duration on the useful visual field in younger and older subjects during simulator driving.

    PubMed

    Rogé, Joceline; Pébayle, Thierry; El Hannachi, Saida; Muzet, Alain

    2003-06-01

    Nine older subjects (40-51 years) and 10 younger subjects (18-30 years) took part in two one-hour driving sessions. They performed a very monotonous task during which they had to follow a vehicle either after a complete night of sleep or after one night of sleep deprivation. While driving their useful visual field was assessed by introducing signals that would appear on the whole road scene. The analysis of the data indicates that the ability to process peripheral signals deteriorates with age, driving duration and sleep deprivation. However, the effects of these three variables on the peripheral visual ability are not similar in a dual task. The driver's useful visual field changes with age and prolongation of the monotonous driving activity according to a tunnel vision phenomenon. On the other hand, a sleep debt deteriorates the useful visual field according to a general interference phenomenon. These results are discussed in terms of decrease in the level of arousal and increase of fatigue.

  4. Driving simulator validation of driver behavior with limited safe vantage points for data collection in work zones.

    PubMed

    Bham, Ghulam H; Leu, Ming C; Vallati, Manoj; Mathur, Durga R

    2014-06-01

    This study is aimed at validating a driving simulator (DS) for the study of driver behavior in work zones. A validation study requires field data collection. For studies conducted in highway work zones, the availability of safe vantage points for data collection at critical locations can be a significant challenge. A validation framework is therefore proposed in this paper, demonstrated using a fixed-based DS that addresses the issue by using a global positioning system (GPS). The validation of the DS was conducted using objective and subjective evaluations. The objective validation was divided into qualitative and quantitative evaluations. The DS was validated by comparing the results of simulation with the field data, which were collected using a GPS along the highway and video recordings at specific locations in a work zone. The constructed work zone scenario in the DS was subjectively evaluated with 46 participants. The objective evaluation established the absolute and relative validity of the DS. The mean speeds from the DS data showed excellent agreement with the field data. The subjective evaluation indicated realistic driving experience by the participants. The use of GPS showed that continuous data collected along the highway can overcome the challenges of unavailability of safe vantage points especially at critical locations. Further, a validated DS can be used for examining driver behavior in complex situations by replicating realistic scenarios. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Study on Drive System of Hybrid Tree Harvester

    PubMed Central

    Xiaozhen, Zhang; Chengjun, Zhou

    2017-01-01

    Hybrid tree harvester with a 60 kW diesel engine combined with a battery pile could be a “green” forest harvesting and transportation system. With the new design, the diesel engine maintains a constant engine speed, keeping fuel consumption low while charging the batteries that drive the forwarder. As an additional energy saving method, the electric motors work as generators to charge the battery pile when the vehicle moves downhill. The vehicle is equipped with six large wheels providing high clearance over uneven terrain while reducing ground pressure. Each wheel is driven via a hub gear by its own alternating current motor, and each of the three wheel pairs can be steered independently. The combination of the diesel engine and six electric motors provides plenty of power for heavy lifting and pulling. The main component parameters of the drive system are calculated and optimized with a set of dynamics and simulated with AVL Cruise software. The results provide practical insights for the fuel tree harvester and are helpful to reduce the structure and size of the tree harvester. Advantage Environment provides information about existing and future products designed to reduce environmental impacts. PMID:28634596

  6. Study on Drive System of Hybrid Tree Harvester.

    PubMed

    Rong-Feng, Shen; Xiaozhen, Zhang; Chengjun, Zhou

    2017-01-01

    Hybrid tree harvester with a 60 kW diesel engine combined with a battery pile could be a "green" forest harvesting and transportation system. With the new design, the diesel engine maintains a constant engine speed, keeping fuel consumption low while charging the batteries that drive the forwarder. As an additional energy saving method, the electric motors work as generators to charge the battery pile when the vehicle moves downhill. The vehicle is equipped with six large wheels providing high clearance over uneven terrain while reducing ground pressure. Each wheel is driven via a hub gear by its own alternating current motor, and each of the three wheel pairs can be steered independently. The combination of the diesel engine and six electric motors provides plenty of power for heavy lifting and pulling. The main component parameters of the drive system are calculated and optimized with a set of dynamics and simulated with AVL Cruise software. The results provide practical insights for the fuel tree harvester and are helpful to reduce the structure and size of the tree harvester. Advantage Environment provides information about existing and future products designed to reduce environmental impacts.

  7. Reservoir simulation of a high viscous crude and strong water drive reservoir in Sarawak, Malaysia

    SciTech Connect

    Ramli, A.

    1995-10-01

    The Bokor field is located offshore Sarawak, Malaysia and is one of the largest fields in the Baram Delta Province. The A3/6 group of reservoirs is the largest among the Bokor reservoir groups. The reservoir comprises a series of multiple, stacked, well-developed, fluviomarine sandstones connected to a large aquifer. Production from this reservoir started in 1983 and since then some 15 MMstb of oil have been produced. To better understand the production performance, displacement mechanism and further development opportunities in this high viscous crude (10 cP) and strong water drive reservoir, a 3D sector reservoir simulation has been carried out. The model comprises 8640 active grid blocks, with 14 strings completed on four reservoir units with separate fluid contacts. The layering system and grid dimensions were found to be critical in the history matching process, which was supported by a X-sectional study carried out prior to embarking on the 3D model. Based on the history match, remaining oil was identified on the eastern flank, at the top of each sand unit (due to water under-running) and in the downdip area due to the existing crestal oriented development. The history matched model was subsequently used to aid further development planning and to formulate a cost-effective reservoir management strategy. Various development scenarios were tested in this 3D model, which include infill drilling, horizontal wells and pressure maintenance by water injection. This paper describes the various steps taken to obtain a good history match over the 10 years of production history and discusses the findings of the prediction runs.

  8. Simulations of electron transport and ignition for direct-drive fast-ignition targets

    SciTech Connect

    Solodov, A. A.; Anderson, K. S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J. A.; Skupsky, S.; Theobald, W.; Stoeckl, C.

    2008-11-15

    The performance of high-gain, fast-ignition fusion targets is investigated using one-dimensional hydrodynamic simulations of implosion and two-dimensional (2D) hybrid fluid-particle simulations of hot-electron transport, ignition, and burn. The 2D/3D hybrid-particle-in-cell code LSP[D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] and the 2D fluid code DRACO[P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] are integrated to simulate the hot-electron transport and heating for direct-drive fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. The self-generated resistive magnetic field is found to collimate the hot-electron beam, increase the coupling efficiency of hot electrons with the target, and reduce the minimum energy required for ignition. Resistive filamentation of the hot-electron beam is also observed. The minimum energy required for ignition is found for hot electrons with realistic angular spread and Maxwellian energy-distribution function.

  9. Simulations of electron transport and ignition for direct-drive fast-ignition targets

    SciTech Connect

    Solodov, A. A.; Anderson, K. S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J. A.; Skupsky, S.; Theobald, W.; Stoeckl, C.

    2008-01-01

    The performance of high-gain, fast-ignition fusion targets is investigated using one-dimensional hydrodynamic simulations of implosion and two-dimensional (2D) hybrid fluid-particle simulations of hot-electron transport, ignition, and burn. The 2D/3D hybrid-particle-in-cell code LSP [D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] and the 2D fluid code DRACO [P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] are integrated to simulate the hot-electron transport and heating for direct-drive fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. The self-generated resistive magnetic field is found to collimate the hot-electron beam, increase the coupling efficiency of hot electrons with the target, and reduce the minimum energy required for ignition. Resistive filamentation of the hot-electron beam is also observed. The minimum energy required for ignition is found for hot electrons with realistic angular spread and Maxwellian energy-distribution function.

  10. Simulated Fuel Economy and Emissions Performance during City and Interstate Driving for a Heavy-Duty Hybrid Truck

    SciTech Connect

    Daw, C. Stuart; Gao, Zhiming; Smith, David E.; Laclair, Tim J.; Pihl, Josh A.; Edwards, K. Dean

    2013-04-08

    We compare simulated fuel economy and emissions for both conventional and hybrid class 8 heavy-duty diesel trucks operating over multiple urban and highway driving cycles. Both light and heavy freight loads were considered, and all simulations included full aftertreatment for NOx and particulate emissions controls. The aftertreatment components included a diesel oxidation catalyst (DOC), urea-selective catalytic NOx reduction (SCR), and a catalyzed diesel particulate filter (DPF). Our simulated hybrid powertrain was configured with a pre-transmission parallel drive, with a single electric motor between the clutch and gearbox. A conventional HD truck with equivalent diesel engine and aftertreatment was also simulated for comparison. Our results indicate that hybridization can significantly increase HD fuel economy and improve emissions control in city driving. However, there is less potential hybridization benefit for HD highway driving. A major factor behind the reduced hybridization benefit for highway driving is that there are fewer opportunities to utilize regenerative breaking. Our aftertreatment simulations indicate that opportunities for passive DPF regeneration are much greater for both hybrid and conventional trucks during highway driving due to higher sustained exhaust temperatures. When passive DPF regeneration is extensively utilized, the fuel penalty for particulate control is virtually eliminated, except for the 0.4%-0.9% fuel penalty associated with the slightly higher exhaust backpressure.

  11. Driving with hemianopia: III. Detection of stationary and approaching pedestrians in a simulator.

    PubMed

    Alberti, Concetta F; Peli, Eli; Bowers, Alex R

    2014-01-20

    To compare blind-side detection performance of drivers with homonymous hemianopia (HH) for stationary and approaching pedestrians, initially appearing at small (4°) or large (14°) eccentricities in a driving simulator. While the stationary pedestrians did not represent an imminent threat, as their eccentricity increased rapidly as the vehicle advanced, the approaching pedestrians maintained a collision course with approximately constant eccentricity, walking or running, toward the travel lane as if to cross. Twelve participants with complete HH and without spatial neglect pressed the horn whenever they detected a pedestrian while driving along predetermined routes in two driving simulator sessions. Miss rates and reaction times were analyzed for 52 stationary and 52 approaching pedestrians. Miss rates were higher and reaction times longer on the blind than the seeing side (P < 0.01). On the blind side, miss rates were lower for approaching than stationary pedestrians (16% vs. 29%, P = 0.01), especially at larger eccentricities (20% vs. 54%, P = 0.005), but reaction times for approaching pedestrians were longer (1.72 vs. 1.41 seconds; P = 0.03). Overall, the proportion of potential blind-side collisions (missed and late responses) was not different for the two paradigms (41% vs. 35%, P = 0.48), and significantly higher than for the seeing side (3%, P = 0.002). In a realistic pedestrian detection task, drivers with HH exhibited significant blind-side detection deficits. Even when approaching pedestrians were detected, responses were often too late to avoid a potential collision.

  12. Driving With Hemianopia: III. Detection of Stationary and Approaching Pedestrians in a Simulator

    PubMed Central

    Alberti, Concetta F.; Peli, Eli; Bowers, Alex R.

    2014-01-01

    Purpose. To compare blind-side detection performance of drivers with homonymous hemianopia (HH) for stationary and approaching pedestrians, initially appearing at small (4°) or large (14°) eccentricities in a driving simulator. While the stationary pedestrians did not represent an imminent threat, as their eccentricity increased rapidly as the vehicle advanced, the approaching pedestrians maintained a collision course with approximately constant eccentricity, walking or running, toward the travel lane as if to cross. Methods. Twelve participants with complete HH and without spatial neglect pressed the horn whenever they detected a pedestrian while driving along predetermined routes in two driving simulator sessions. Miss rates and reaction times were analyzed for 52 stationary and 52 approaching pedestrians. Results. Miss rates were higher and reaction times longer on the blind than the seeing side (P < 0.01). On the blind side, miss rates were lower for approaching than stationary pedestrians (16% vs. 29%, P = 0.01), especially at larger eccentricities (20% vs. 54%, P = 0.005), but reaction times for approaching pedestrians were longer (1.72 vs. 1.41 seconds; P = 0.03). Overall, the proportion of potential blind-side collisions (missed and late responses) was not different for the two paradigms (41% vs. 35%, P = 0.48), and significantly higher than for the seeing side (3%, P = 0.002). Conclusions. In a realistic pedestrian detection task, drivers with HH exhibited significant blind-side detection deficits. Even when approaching pedestrians were detected, responses were often too late to avoid a potential collision. PMID:24346175

  13. The role of motion platform on postural instability and head vibration exposure at driving simulators.

    PubMed

    Aykent, B; Merienne, F; Paillot, D; Kemeny, A

    2014-02-01

    This paper explains the effect of a motion platform for driving simulators on postural instability and head vibration exposure. The sensed head level-vehicle (visual cues) level longitudinal and lateral accelerations (ax,sensed=ax_head and ay,sensed=ay_head, ayv=ay_veh and ayv=ay_veh) were saved by using a motion tracking sensor and a simulation software respectively. Then, associated vibration dose values (VDVs) were computed at head level during the driving sessions. Furthermore, the postural instabilities of the participants were measured as longitudinal and lateral subject body centre of pressure (XCP and YCP, respectively) displacements just after each driving session via a balance platform. The results revealed that the optic-head inertial level longitudinal accelerations indicated a negative non-significant correlation (r=-.203, p=.154>.05) for the static case, whereas the optic-head inertial longitudinal accelerations depicted a so small negative non-significant correlation (r=-.066, p=.643>.05) that can be negligible for the dynamic condition. The XCP for the dynamic case indicated a significant higher value than the static situation (t(47), p<.0001). The VDVx for the dynamic case yielded a significant higher value than the static situation (U(47), p<.0001). The optic-head inertial lateral accelerations resulted a negative significant correlation (r=-.376, p=.007<.05) for the static platform, whereas the optic-head inertial lateral accelerations showed a positive significant correlation (r=.418, p=.002<.05) at dynamic platform condition. The VDVy for the static case indicated a significant higher value rather than the dynamic situation (U(47), p<.0001). The YCP for the static case yielded significantly higher than the dynamic situation (t(47), p=.001<0.05).

  14. Assessing Video Games to Improve Driving Skills: A Literature Review and Observational Study

    PubMed Central

    Sue, Damian; Vichitvanichphong, Suchada

    2014-01-01

    Background For individuals, especially older adults, playing video games is a promising tool for improving their driving skills. The ease of use, wide availability, and interactivity of gaming consoles make them an attractive simulation tool. Objective The objective of this study was to look at the feasibility and effects of installing video game consoles in the homes of individuals looking to improve their driving skills. Methods A systematic literature review was conducted to assess the effect of playing video games on improving driving skills. An observatory study was performed to evaluate the feasibility of using an Xbox 360 Kinect console for improving driving skills. Results Twenty–nine articles, which discuss the implementation of video games in improving driving skills were found in literature. On our study, it was found the Xbox 360 with Kinect is capable of improving physical and mental activities. Xbox Video games were introduced to engage players in physical, visual and cognitive activities including endurance, postural sway, reaction time, eyesight, eye movement, attention and concentration, difficulties with orientation, and semantic fluency. However, manual dexterity, visuo-spatial perception and binocular vision could not be addressed by these games. It was observed that Xbox Kinect (by incorporating Kinect sensor facilities) combines physical, visual and cognitive engagement of players. These results were consistent with those from the literature review. Conclusions From the research that has been carried out, we can conclude that video game consoles are a viable solution for improving user’s physical and mental state. In future we propose to carry a thorough evaluation of the effects of video games on driving skills in elderly people. PMID:25654355

  15. Assessing video games to improve driving skills: a literature review and observational study.

    PubMed

    Sue, Damian; Ray, Pradeep; Talaei-Khoei, Amir; Jonnagaddala, Jitendra; Vichitvanichphong, Suchada

    2014-08-07

    For individuals, especially older adults, playing video games is a promising tool for improving their driving skills. The ease of use, wide availability, and interactivity of gaming consoles make them an attractive simulation tool. The objective of this study was to look at the feasibility and effects of installing video game consoles in the homes of individuals looking to improve their driving skills. A systematic literature review was conducted to assess the effect of playing video games on improving driving skills. An observatory study was performed to evaluate the feasibility of using an Xbox 360 Kinect console for improving driving skills. Twenty-nine articles, which discuss the implementation of video games in improving driving skills were found in literature. On our study, it was found the Xbox 360 with Kinect is capable of improving physical and mental activities. Xbox Video games were introduced to engage players in physical, visual and cognitive activities including endurance, postural sway, reaction time, eyesight, eye movement, attention and concentration, difficulties with orientation, and semantic fluency. However, manual dexterity, visuo-spatial perception and binocular vision could not be addressed by these games. It was observed that Xbox Kinect (by incorporating Kinect sensor facilities) combines physical, visual and cognitive engagement of players. These results were consistent with those from the literature review. From the research that has been carried out, we can conclude that video game consoles are a viable solution for improving user's physical and mental state. In future we propose to carry a thorough evaluation of the effects of video games on driving skills in elderly people.

  16. [Medicolegal aspects of driving ability and discussion of study methods].

    PubMed

    Berghaus, G

    2008-06-01

    Medicolegal aspects of driving ability primarily concern patients themselves, because they are responsible when driving in traffic while under drug treatment. Pain patients taking analgesic medication prescribed by a doctor do not commit an offence, insofar as they are able to drive. A doctor's main duty consists of informing the patient about the way a given disease or drug intake affects driving ability. Patients have the duty to inform themselves about the drug they are taking and to assess their driving ability each time before they drive a car.

  17. Integrated simulations of implosion, electron transport, and heating for direct-drive fast-ignition targets

    SciTech Connect

    Solodov, A. A.; Anderson, K. S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J. A.; Skupsky, S.; Theobald, W.; Stoeckl, C.

    2009-05-15

    A thorough understanding of future integrated fast-ignition experiments combining compression and heating of high-density thermonuclear fuel requires hybrid (fluid+particle) simulations of the implosion and ignition process. Different spatial and temporal scales need to be resolved to model the entire fast-ignition experiment. The two-dimensional (2D) axisymmetric hydrocode DRACO[P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] and the 2D/three-dimensional hybrid particle-in-cell code LSP[D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] have been integrated to simulate the implosion and heating of direct-drive, fast-ignition fusion targets. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. The results from integrated simulations of cone-in-shell CD targets designed for fast-ignition experiments on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997); C. Stoeckl et al., Fusion Sci. Technol. 49, 367 (2006)] are presented. Target heating and neutron yields are computed. The results from LSP simulations of electron transport in solid-density plastic targets are also presented. They confirm an increase in the electron divergence angle with the laser intensity in the current experiments. The self-generated resistive magnetic field is found to collimate the hot-electron beam and increase the coupling efficiency of hot electrons with the target. Resistive filamentation of the hot-electron beam is also observed.

  18. Integrated Simulations of Implosion, Electron Transport, and Heating for Direct-Drive Fast-Ignition Targets

    SciTech Connect

    Solodov, A.A.; Anderson, K.S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J.A.; Skupsky, S.; Theobald, W.; Stoeckl, C.

    2009-04-28

    A thorough understanding of future integrated fast-ignition experiments combining compression and heating of high-density thermonuclear fuel requires hybrid (fluid+particle) simulations of the implosion and ignition process. Different spatial and temporal scales need to be resolved to model the entire fast-ignition experiment. The two-dimensional (2D) axisymmetric hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] and the 2D/three-dimensional hybrid particle-in-cell code LSP [D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] have been integrated to simulate the implosion and heating of direct-drive, fast-ignition fusion targets. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. The results from integrated simulations of cone-in-shell CD targets designed for fast-ignition experiments on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997); C. Stoeckl et al., Fusion Sci. Technol. 49, 367 (2006)] are presented. Target heating and neutron yields are computed. The results from LSP simulations of electron transport in solid-density plastic targets are also presented. They confirm an increase in the electron divergence angle with the laser intensity in the current experiments. The self-generated resistive magnetic field is found to collimate the hot-electron beam and increase the coupling efficiency of hot electrons with the target. Resistive filamentation of the hot-electron beam is also observed.

  19. Compensatory eye and head movements of patients with homonymous hemianopia in the naturalistic setting of a driving simulation.

    PubMed

    Bahnemann, Markus; Hamel, Johanna; De Beukelaer, Sophie; Ohl, Sven; Kehrer, Stefanie; Audebert, Heinrich; Kraft, Antje; Brandt, Stephan A

    2015-02-01

    Homonymous hemianopia (HH) is a frequent deficit resulting from lesions to post-chiasmal brain structures with a significant negative impact on activities of daily living. To address the question how patients with HH may compensate their visual field defect in a naturalistic environment, we performed a driving simulation experiment and quantitatively analyzed both eye and head movements using a head-mounted pupil camera. 14 patients with HH and 14 matched healthy control subjects participated in the study. Based on the detection performance of dynamically moving obstacles, which appeared unexpectedly along the sides of the road track, we divided the patient group into a high- and a low-performance group. Then, we compared parameters of eye and head movements between the two patient groups and the matched healthy control group to identify those which mediate successful detection of potentially hazardous objects. Differences in detection rates could not be explained by demographic variables or the extent of the visual field defect. Instead, high performance of patients with HH in the naturalistic setting of our driving simulation depended on an adapted visual exploratory behavior characterized by a relative increase in the amplitude and a corresponding increase in the peak velocity of saccades, widening horizontally the distribution of eye movements, and by a shift of the overall distribution of saccades into the blind hemifield. The result of the group comparison analyses was confirmed by a subsequent stepwise regression analysis which identified the horizontal spread of eye movements as single factor predicting the detection of hazardous objects.

  20. Novice Drivers' Risky Driving Behavior, Risk Perception, and Crash Risk: Findings From the DRIVE Study

    PubMed Central

    Senserrick, Teresa; Boufous, Soufiane; Stevenson, Mark; Chen, Huei-Yang; Woodward, Mark; Norton, Robyn

    2009-01-01

    Objectives. We explored the risky driving behaviors and risk perceptions of a cohort of young novice drivers and sought to determine their associations with crash risk. Methods. Provisional drivers aged 17 to 24 (n = 20 822) completed a detailed questionnaire that included measures of risk perception and behaviors; 2 years following recruitment, survey data were linked to licensing and police-reported crash data. Poisson regression models that adjusted for multiple confounders were created to explore crash risk. Results. High scores on questionnaire items for risky driving were associated with a 50% increased crash risk (adjusted relative risk = 1.51; 95% confidence interval = 1.25, 1.81). High scores for risk perception (poorer perceptions of safety) were also associated with increased crash risk in univariate and multivariate models; however, significance was not sustained after adjustment for risky driving. Conclusions. The overrepresentation of youths in crashes involving casualties is a significant public health issue. Risky driving behavior is strongly linked to crash risk among young drivers and overrides the importance of risk perceptions. Systemwide intervention, including licensing reform, is warranted. PMID:19608953

  1. Evaluating and Enhancing Driving Ability among Teens with Autism Spectrum Disorder

    DTIC Science & Technology

    2015-06-01

    Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Objective: This study evaluated whether Virtual Reality Driving Simulation Training (VRDST) could improve...Asperger, driving, virtual reality , driving simulation, driving safety 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Unclassified 18. NUMBER...driver’s license, and (2) use Virtual Reality Driving Simulation (VRDS) training to aid individuals with ASD to safely operate a motor vehicle. This

  2. Marihuana and driving.

    PubMed

    Moskowitz, H

    1985-08-01

    A review was performed of the marihuana and driving literature, both epidemiological and experimental. It was noted that epidemiological studies face considerable difficulties in obtaining estimates of risks involved for drivers utilizing marihuana due to the rapid decline in blood levels of tetrahydrocannabinol. On the other hand, experimental studies examining the relationship between administered marihuana dose and performance have identified many driving-related areas as exhibiting impairment. Areas impaired include coordination, tracking, perception, vigilance and performance in both driving simulators and on the road. Other behavioral areas of lesser importance for driving also exhibited evidence of impairment by marihuana. Areas for further research are suggested.

  3. Pilot study for quantifying driving characteristics during power wheelchair soccer.

    PubMed

    Kumar, Amit; Karmarkar, Amol M; Collins, Diane M; Souza, Ana; Oyster, Michelle L; Cooper, Rosemarie; Cooper, Rory A

    2012-01-01

    This study determined the driving characteristics of wheelchair users during power wheelchair soccer games. Data for this study were collected at the 28th and 29th National Veterans Wheelchair Games. Nineteen veterans who were 18 years or older and power wheelchair soccer players completed a brief demographic survey and provided information about their power wheelchairs. A customized data-logging device was placed on each participant's wheelchair before power soccer game participation. The data logger was removed at the end of the final game for each participant. The average distance traveled during the games was 899.5 +/- 592.5 m, and the average maximum continuous distance traveled was 256.0 +/- 209.4 m. The average wheelchair speed was 0.8 +/- 0.2 m/s, and the average duration of driving time was 17.6 +/- 8.3 min. Average proportion of time spent at a speed >1 m/s was 30.7% +/- 33.8%, between 0.5 and 1 m/s was 16.2% +/- 34.4%, and <0.5 m/s was 21.4% +/- 24.3%. The information from this descriptive study provides insight for future research in the field of adapted sports for people with high levels of impairments who use power wheelchairs for their mobility.

  4. Comprehensive 3D-elastohydrodynamic simulation of hermetic compressor crank drive

    NASA Astrophysics Data System (ADS)

    Posch, S.; Hopfgartner, J.; Berger, E.; Zuber, B.; Almbauer, R.; Schöllauf, P.

    2017-08-01

    Mechanical, electrical and thermodynamic losses form the major loss mechanisms of hermetic compressors for refrigeration application. The present work deals with the investigation of the mechanical losses of a hermetic compressor crank drive. Focus is on 3d-elastohydrodynamic (EHD) modelling of the journal bearings, piston-liner contact and piston secondary motion in combination with multi-body and structural dynamics of the crank drive elements. A detailed description of the model development within the commercial software AVL EXCITE Power Unit is given in the work. The model is used to create a comprehensive analysis of the mechanical losses of a hermetic compressor. Further on, a parametric study concerning oil viscosity and compressor speed is carried out which shows the possibilities of the usage of the model in the development process of hermetic compressors for refrigeration application. Additionally, the usage of the results in an overall thermal network for the determination of the thermal compressor behaviour is discussed.

  5. Behavioural reactivation and subjective assessment of the state of vigilance--application to simulated car driving.

    PubMed

    Bonnefond, Anne; Rogé, Joceline; Muzet, Alain

    2006-01-01

    The frequency of some behaviour (such as self-centred gestures) increases during a task that leads to the occurrence of low-vigilance episodes. These gestures can be useful in stimulating oneself. A study carried out in 20 adults has enabled us to state that motor activity (recorded with an actimeter) increases with the duration of a monotonous driving task and sleep deprivation. The analysis of the scores recorded using the Karolinska Sleepiness Scale has shown that drivers can assess the deterioration of their state of vigilance according to the actual sleep preceding the driving test. Finally, the joint analysis of the subjective and objective data revealed a co-variation of these two types of indices. We discuss the stimulatory function of the motor activity in a task leading to the occurrence of low-vigilance episodes by investigating, among other things, the use, conscious or not, of this type of activity.

  6. Integrated Plasma Simulation of Lower Hybrid Current Drive Modification of Sawtooth in Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Bonoli, P. T.; Hubbard, A. E.; Schmidt, A. E.; Wright, J. C.; Kessel, C. E.; Batchelor, D. B.; Berry, L. A.; Harvey, R. W.

    2010-11-01

    Experiments were performed in Alcator C-Mod, where the onset time for sawteeth was delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through injection of off-axis LH current drive power [1]. In this poster we discuss simulations of these experiments using the Integrated Plasma Simulator (IPS) [2], through which driven current density profiles and hard x-ray spectra are computed using a ray tracing code (GENRAY) and Fokker Planck code (CQL3D) [3], that are executed repeatedly in time. The background plasma is evolved in these simulations using the TSC transport code with the Porcelli sawtooth model [4]. [4pt] [1] C. E. Kessel et al, Bull. of the Am. Phys. Soc. 53, Poster PP6.00074 (2008). [0pt] [2] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008). [0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Mtg. on Sim. and Mod. of Therm. Plasmas, Montreal, Canada (1992). [0pt] [4] S. C. Jardin et al, Journal Comp. Phys. 66, 481 (1986).

  7. Three-dimensional magnetohydrodynamic simulations of the Helicity Injected Torus with Steady Inductive drive

    SciTech Connect

    Izzo, V.A.; Jarboe, T.R.

    2005-05-15

    The Helicity Injected Torus with Steady Inductive drive (HIT-SI) [P. E. Sieck, W. T. Hamp, V. A. Izzo, T. R. Jarboe, B. A. Nelson, R. G. O'Neill, A. J. Redd, and R. J. Smith, IEEE Conference Record-Abstracts. 31st IEEE International Conference On Plasma Science (IEEE Catalog No. 04CH37537), 2004, p. 160] is a spheromak driven by steady inductive helicity injection (SIHI) and consists of the toroidally symmetric spheromak confinement region and two nonsymmetric helicity injectors. The three-dimensional (3D) magnetohydrodynamic code NIMROD [A. H. Glasser, C. R. Sovinec, R. A. Nebel, T. A. Gianakon, S. J. Plimpton, M. S. Chu, and D. D. Schnack, Plasma Phys. Controlled Fusion, 41, A747 (1999)] is used to simulate HIT-SI operation, but the code's toroidally symmetric boundary requires a creative treatment of the injectors. Sustained HIT-SI operation is simulated with nonaxisymmetric boundary conditions. In driven simulations at low Lundquist number S no n=0 fields are generated as a result of relaxation of the predominantly n=1 injector fields until the injectors are quickly shut off. At S=500, an n=0 component arises due to relaxation during sustainment. As S is increased further, the ratio of n=0 (equilibrium) fields to n=1 (injector) fields increases. The effects of a thin insulating boundary layer on the plasma decay time are also discussed.

  8. Test Results From a Direct Drive Gas Reactor Simulator Coupled to a Brayton Power Conversion Unit

    NASA Technical Reports Server (NTRS)

    Hervol, David S.; Briggs, Maxwell H.; Owen, Albert K.; Bragg-Sitton, Shannon M.

    2009-01-01

    The Brayton Power Conversion Unit (BPCU) located at NASA Glenn Research Center (GRC) in Cleveland, OH is a closed cycle system incorporating a turboaltemator, recuperator, and gas cooler connected by gas ducts to an external gas heater. For this series of tests, the BPCU was modified by replacing the gas heater with the Direct Drive Gas heater or DOG. The DOG uses electric resistance heaters to simulate a fast spectrum nuclear reactor similar to those proposed for space power applications. The combined system thermal transient behavior was the focus of these tests. The BPCU was operated at various steady state points. At each point it was subjected to transient changes involving shaft rotational speed or DOG electrical input. This paper outlines the changes made to the test unit and describes the testing that took place along with the test results.

  9. Driving performance on the descending limb of blood alcohol concentration (BAC) in undergraduate students: a pilot study.

    PubMed

    Tremblay, Mathieu; Gallant, François; Lavallière, Martin; Chiasson, Martine; Silvey, Dustin; Behm, David; Albert, Wayne J; Johnson, Michel J

    2015-01-01

    Young drivers are overrepresented in collisions resulting in fatalities. It is not uncommon for young drivers to socially binge drink and decide to drive a vehicle a few hours after consumption. To better understand the risks that may be associated with this behaviour, the present study has examined the effects of a social drinking bout followed by a simulated drive in undergraduate students on the descending limb of their BAC (blood alcohol concentration) curve. Two groups of eight undergraduate students (n = 16) took part in this study. Participants in the alcohol group were assessed before drinking, then at moderate and low BAC as well as 24 hours post-acute consumption. This group consumed an average of 5.3 ± 1.4 (mean ± SD) drinks in an hour in a social context and were then submitted to a driving and a predicted crash risk assessment. The control group was assessed at the same time points without alcohol intake or social context.; at 8 a.m., noon, 3 p.m. and 8 a.m. the next morning. These multiple time points were used to measure any potential learning effects from the assessment tools (i.e. driving simulator and useful field of view test (UFOV)). Diminished driving performance at moderate BAC was observed with no increases in predicted crash risk. Moderate correlations between driving variables were observed. No association exists between driving variables and UFOV variables. The control group improved measures of selective attention after the third assessment. No learning effect was observed from multiple sessions with the driving simulator. Our results show that a moderate BAC, although legal, increases the risky behaviour. Effects of alcohol expectancy could have been displayed by the experimental group. UFOV measures and predicted crash risk categories were not sensitive enough to predict crash risk for young drivers, even when intoxicated.

  10. Driving Performance on the Descending Limb of Blood Alcohol Concentration (BAC) in Undergraduate Students: A Pilot Study

    PubMed Central

    Silvey, Dustin; Behm, David; Albert, Wayne J.

    2015-01-01

    Young drivers are overrepresented in collisions resulting in fatalities. It is not uncommon for young drivers to socially binge drink and decide to drive a vehicle a few hours after consumption. To better understand the risks that may be associated with this behaviour, the present study has examined the effects of a social drinking bout followed by a simulated drive in undergraduate students on the descending limb of their BAC (blood alcohol concentration) curve. Two groups of eight undergraduate students (n = 16) took part in this study. Participants in the alcohol group were assessed before drinking, then at moderate and low BAC as well as 24 hours post-acute consumption. This group consumed an average of 5.3 ± 1.4 (mean ± SD) drinks in an hour in a social context and were then submitted to a driving and a predicted crash risk assessment. The control group was assessed at the same time points without alcohol intake or social context.; at 8 a.m., noon, 3 p.m. and 8 a.m. the next morning. These multiple time points were used to measure any potential learning effects from the assessment tools (i.e. driving simulator and useful field of view test (UFOV)). Diminished driving performance at moderate BAC was observed with no increases in predicted crash risk. Moderate correlations between driving variables were observed. No association exists between driving variables and UFOV variables. The control group improved measures of selective attention after the third asessement. No learning effect was observed from multiple sessions with the driving simulator. Our results show that a moderate BAC, although legal, increases the risky behaviour. Effects of alcohol expectancy could have been displayed by the experimental group. UFOV measures and predicted crash risk categories were not sentitive enough to predict crash risk for young drivers, even when intoxicated. PMID:25723618

  11. Observation of early shell-dopant mix in OMEGA direct-drive implosions and comparisons with radiation-hydrodynamic simulations

    SciTech Connect

    Baumgaertel, J. A.; Bradley, P. A.; Hsu, S. C.; Cobble, J. A.; Hakel, P.; Tregillis, I. L.; Krasheninnikova, N. S.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Obrey, K. D.; Batha, S.; Johns, H.; Joshi, T.; Mayes, D.; Mancini, R. C.; Nagayama, T.

    2014-05-15

    Temporally, spatially, and spectrally resolved x-ray image data from direct-drive implosions on OMEGA were interpreted with the aid of radiation-hydrodynamic simulations. Neither clean calculations nor those using a turbulent mix model can explain fully the observed migration of shell-dopant material (titanium) into the core. Shell-dopant migration was observed via time-dependent, spatially integrated spectra, and spatially and spectrally resolved x-ray images of capsule implosions and resultant dopant emissions. The titanium emission was centrally peaked in narrowband x-ray images. In post-processed clean simulations, the peak titanium emission forms in a ring in self-emission images as the capsule implodes. Post-processed simulations with mix reproduce trends in time-dependent, spatially integrated spectra, as well having centrally peaked Ti emission in synthetic multiple monochromatic imager. However, mix simulations still do not transport Ti to the core as is observed in the experiment. This suggests that phenomena in addition to the turbulent mix must be responsible for the transport of Ti. Simple diffusion estimates are unable to explain the early Ti mix into the core. Mechanisms suggested for further study are capsule surface roughness, illumination non-uniformity, and shock entrainment.

  12. System studies of rf current drive for MST

    SciTech Connect

    Anderson, J. K.; Burke, D. R.; Forest, C. B.; Goetz, J. A.; Hendries, E. R.; Seltzman, A. H.; Thomas, M. A.; Diem, S.; Harvey, R. W.; Kaufman, M. C.

    2011-12-23

    Two rf schemes are being studied on the MST reversed field pinch for their potential in current profile control experiments. MHD modeling has shown that a substantial externally-driven off axis parallel current can improve stability of the dominant core tearing modes. A radially localized axisymmetric population of fast electrons has been observed by SXR emission during LH injection (100kW at 800MHz), and is consistent with CQL3D modeling which predicts a small driven current. Computational work suggests that doubling the input power will statistically improve the LH-induced SXR signal to background ratio, and that about 2MW of injected power (an order of magnitude increase) will drive enough current for stabilization of tearing modes. Additionally, a 1 MW 5.5 GHz electron Bernstein wave (EBW) experiment is under construction, which utilizes a very simple and compact antenna compatible with the demands of the RFP. EBW allows access to electron cyclotron heating and current drive in the overdense plasma. Coupling of the external electromagnetic wave to the EBW has been demonstrated, and initial tests at {approx}100kW power have produced a small, localized xray flux consistent with rf heating and high diffusivity of fast electrons. Computational work is currently underway to answer the very important questions of how much power is required, and what level of electron diffusivity is tolerable, to generate a consequential amount of EBW current.

  13. Pershing 2 simulation studies

    NASA Astrophysics Data System (ADS)

    Knight, J. D.; Lynch, R. L.; Pyles, D. A.; Seitz, R. N.; Thornton, T. V.

    1982-07-01

    Pershing 2 flight simulations were performed using the U70 missile simulation program to determine (1) in the event of an accidental nozzle deflection, how fast the missile would leave its (safe) flight corridor; (2) how well the U70 aerodynamic simulation matches the actual flight data; and (3) the trajectory profiles for nine Tactical Ballistic Missile flight trajectories. Also an advanced simulation program developed by TRW, Inc. was partially converted to run on an inhouse computer.

  14. Studies of Plastic-Ablator Compressibility for Direct-Drive Inertial Confinement Fusion on Omega

    SciTech Connect

    Hu, S. X.; Smalyuk, V. A.; Goncharov, V. N.; Knauer, J. P.; Radha, P. B.; Igumenshchev, I. V.; Marozas, J. A.; Stoeckl, C.; Yaakobi, B.; Shvarts, D.; Sangster, T. C.; McKenty, P. W.; Meyerhofer, D. D.; Skupsky, S.; McCrory, R. L.

    2008-05-09

    The compression of planar plastic targets was studied with x-ray radiography in the range of laser intensities of I{approx}0.5 to 1.5x10{sup 15} W/cm{sup 2} using square (low-compression) and shaped (high-compression) pulses. Two-dimensional simulations with the radiative hydrocode DRACO show good agreement with measurements at laser intensities up to I{approx}10{sup 15} W/cm{sup 2}. These results provide the first experimental evidence for low-entropy, adiabatic compression of plastic shells in the laser intensity regime relevant to direct-drive inertial confinement fusion. A density reduction near the end of the drive at a high intensity of I{approx}1.5x10{sup 15} W/cm{sup 2} has been correlated with the hard x-ray signal caused by hot electrons from two-plasmon-decay instability.

  15. Studies of Plastic-Ablator Compresibility for Direct-Drive Inertial Confinement Fusion on OMEGA

    SciTech Connect

    Hu, S.X.; Smalyuk, V.A.; Goncharov, V.N.; Knauer, J.P.; Radha, P.B.; Igumenshchev, I.V.; Marozas, J.A.; Stoeckl, C.; Yaakobi, B.; Shvarts, D.; Sangster, T.C.; McKenty, P.W.; Meyerhofer, D.D.; Skupsky, S.; McCrory, R.L.

    2008-05-07

    The compression of planar plastic targets was studied with x-ray radiography in the range of laser intensities of I ~ 0.5 to 1.5 x 10^15 W/cm^2 using square (low-compression) and shaped (high-compression) pulses. Two-dimensional simulations with the radiative hydrocode DRACO show good agreement with measurements at laser intensities up to I ~ 10^15 W/cm^2. These resulsts provide the first experimental evidence for low-entropy, adiabatic compression of plastic shells in the laser intensity regime relevant to direct-drive inertial confinement fusion. A density reduction near the end of the drive at a high intensity of I ~ 1.5 x 10^15 W/cm^2 has been correlated with the hard x-ray signal caused by hot electrons from two-plasmon-decay instability.

  16. Studies of plastic-ablator compressibility for direct-drive inertial confinement fusion on OMEGA.

    PubMed

    Hu, S X; Smalyuk, V A; Goncharov, V N; Knauer, J P; Radha, P B; Igumenshchev, I V; Marozas, J A; Stoeckl, C; Yaakobi, B; Shvarts, D; Sangster, T C; McKenty, P W; Meyerhofer, D D; Skupsky, S; McCrory, R L

    2008-05-09

    The compression of planar plastic targets was studied with x-ray radiography in the range of laser intensities of I approximately 0.5 to 1.5x10(15) W/cm2 using square (low-compression) and shaped (high-compression) pulses. Two-dimensional simulations with the radiative hydrocode DRACO show good agreement with measurements at laser intensities up to I approximately 10(15) W/cm2. These results provide the first experimental evidence for low-entropy, adiabatic compression of plastic shells in the laser intensity regime relevant to direct-drive inertial confinement fusion. A density reduction near the end of the drive at a high intensity of I approximately 1.5x10(15) W/cm2 has been correlated with the hard x-ray signal caused by hot electrons from two-plasmon-decay instability.

  17. Steering the conversation: A linguistic exploration of natural language interactions with a digital assistant during simulated driving.

    PubMed

    Large, David R; Clark, Leigh; Quandt, Annie; Burnett, Gary; Skrypchuk, Lee

    2017-09-01

    Given the proliferation of 'intelligent' and 'socially-aware' digital assistants embodying everyday mobile technology - and the undeniable logic that utilising voice-activated controls and interfaces in cars reduces the visual and manual distraction of interacting with in-vehicle devices - it appears inevitable that next generation vehicles will be embodied by digital assistants and utilise spoken language as a method of interaction. From a design perspective, defining the language and interaction style that a digital driving assistant should adopt is contingent on the role that they play within the social fabric and context in which they are situated. We therefore conducted a qualitative, Wizard-of-Oz study to explore how drivers might interact linguistically with a natural language digital driving assistant. Twenty-five participants drove for 10 min in a medium-fidelity driving simulator while interacting with a state-of-the-art, high-functioning, conversational digital driving assistant. All exchanges were transcribed and analysed using recognised linguistic techniques, such as discourse and conversation analysis, normally reserved for interpersonal investigation. Language usage patterns demonstrate that interactions with the digital assistant were fundamentally social in nature, with participants affording the assistant equal social status and high-level cognitive processing capability. For example, participants were polite, actively controlled turn-taking during the conversation, and used back-channelling, fillers and hesitation, as they might in human communication. Furthermore, participants expected the digital assistant to understand and process complex requests mitigated with hedging words and expressions, and peppered with vague language and deictic references requiring shared contextual information and mutual understanding. Findings are presented in six themes which emerged during the analysis - formulating responses; turn-taking; back

  18. Predictors of driving outcomes including both crash involvement and driving cessation in a prospective study of Japanese older drivers.

    PubMed

    Kosuge, Ritsu; Okamura, Kazuko; Kihira, Makoto; Nakano, Yukako; Fujita, Goro

    2017-09-01

    The first aim of this study was to investigate predictors of future traffic crash involvement, taking into account bias in the handling of data for former drivers. The second aim was to compare characteristics of former drivers and crash-involved drivers in order to gain an understanding of appropriate driving cessation among older drivers. In all, 154 drivers aged 70 years or older participated in the baseline interview and the follow-up survey conducted two years later. In the baseline interview, participants were asked to respond to a questionnaire, take the Useful Field of View test(®) (UFOV), and complete the Mini-Mental State Examination. In the follow-up survey, participants were asked by mail or telephone whether they had stopped driving. Participants reporting that they still drove were invited to participate in a subsequent interview. Based on the information obtained in the follow-up survey, participants were classified as follows: driving cessation group (n=26); crash-involved group (n=18); and crash-free group (n=110). A multinomial logistic regression was then used to analyse the data. Contrary to the results of previous studies, we found older age to be associated with crash involvement but not with driving cessation. The cessation group had more decreased cognitive processing speed than the crash-involved and crash-free groups. Crash history was also predictive of crash involvement. Participants who were subject to license renewal between baseline and follow-up had a greater tendency to continue driving. Results suggested that age and crash history could potentially identify high-risk older drivers. The predictive power of cognitive processing speed is reduced under certain conditions. License-renewal procedures may induce Japanese older adults to continue driving. Future studies should use a large national sample to confirm the results of the present study. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Driving Simulator Performance in Novice Drivers with Autism Spectrum Disorder: The Role of Executive Functions and Basic Motor Skills

    ERIC Educational Resources Information Center

    Cox, Stephany M.; Cox, Daniel J.; Kofler, Michael J.; Moncrief, Matthew A.; Johnson, Ronald J.; Lambert, Ann E.; Cain, Sarah A.; Reeve, Ronald E.

    2016-01-01

    Previous studies have shown that individuals with autism spectrum disorder (ASD) demonstrate poorer driving performance than their peers and are less likely to obtain a driver's license. This study aims to examine the relationship between driving performance and executive functioning for novice drivers, with and without ASD, using a driving…

  20. Two Dimensional Simulations of Plastic-Shell, Direct-Drive Implosions on OMEGA

    SciTech Connect

    Radha, P B; Goncharov, V N; Collins, T B; Delettrez, J A; Elbaz, Y; Glebov, V Y; Keck, R L; Keller, D E; Knauer, J P; Marozas, J A; Marshall, F J; McKenty, P W; Meyerhofer, D D; Regan, S P; Sangster, T C; Shvarts, D; Skupsky, S; Srebro, Y; Town, R J; Stoeckl, C

    2004-09-27

    Multidimensional hydrodynamic properties of high-adiabat direct-drive plastic-shell implosions on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] are investigated using the multidimensional hydrodynamic code, DRACO. Multimode simulations including the effects of nonuniform illumination and target roughness indicate that shell stability during the acceleration phase plays a critical role in determining target performance. For thick shells that remain integral during the acceleration phase, target yields are significantly reduced by the combination of the long-wavelength ({ell} < 10) modes due to surface roughness and beam imbalance and the intermediate modes (20 {le} {ell} {le} 50) due to single-beam nonuniformities. The neutron-production rate for these thick shells truncates relative to one-dimensional (1-D) predictions. The yield degradation in the thin shells is mainly due to shell breakup at short wavelengths ({lambda} {approx} {Delta}, where {Delta} is the in-flight shell thickness). The neutron-rate curves for the thinner shells have significantly lower amplitudes and a fall-off that is less steep than 1-D rates. DRACO simulation results are consistent with experimental observations.

  1. Two-dimensional simulations of plastic-shell, direct-drive implosions on OMEGA

    SciTech Connect

    Radha, P.B.; Goncharov, V.N.; Collins, T.J.B.; Delettrez, J.A.; Elbaz, Y.; Glebov, V.Yu.; Keck, R.L.; Keller, D.E.; Knauer, J.P.; Marozas, J.A.; Marshall, F.J.; McKenty, P.W.; Meyerhofer, D.D.; Regan, S.P.; Sangster, T.C.; Shvarts, D.; Skupsky, S.; Srebro, Y.; Town, R.P.J.; Stoeckl, C.

    2005-03-01

    Multidimensional hydrodynamic properties of high-adiabat direct-drive plastic-shell implosions on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] are investigated using the multidimensional hydrodynamic code, DRACO [D. Keller et al., Bull. Am. Phys. Soc. 44, 37 (1999)]. Multimode simulations including the effects of nonuniform illumination and target roughness indicate that shell stability during the acceleration phase plays a critical role in determining target performance. For thick shells that remain integral during the acceleration phase, target yields are significantly reduced by the combination of the long-wavelength (l<10) modes due to surface roughness and beam imbalance and the intermediate modes (20{<=}l{<=}50) due to single-beam nonuniformities. The neutron-production rate for these thick shells truncates relative to one-dimensional (1D) predictions. The yield degradation in the thin shells is mainly due to shell breakup at short wavelengths ({lambda}{approx}{delta}, where {delta} is the in-flight shell thickness). The neutron-rate curves for the thinner shells have significantly lower amplitudes and a fall-off that is less steep than 1D rates. DRACO simulation results are consistent with experimental observations.

  2. Handling performance control for hybrid 8-wheel-drive vehicle and simulation verification

    NASA Astrophysics Data System (ADS)

    Ni, Jun; Hu, Jibin

    2016-08-01

    In order to improve handling performance of a hybrid 8-Wheel-Drive vehicle, the handling performance control strategy was proposed. For armoured vehicle, besides handling stability in high speed, the minimum steer radius in low speed is also a key tactical and technical index. Based on that, the proposed handling performance control strategy includes 'Handling Stability' and 'Radius Minimization' control modes. In 'Handling Stability' control mode, 'Neutralsteer Radio' is defined to adjust the steering characteristics to satisfy different demand in different speed range. In 'Radius Minimization' control mode, the independent motors are controlled to provide an additional yaw moment to decrease the minimum steer radius. In order to verify the strategy, a simulation platform was built including engine and continuously variable transmission systems, generator and battery systems, independent motors and controllers systems, vehicle dynamic and tyre mechanical systems. The simulation results show that the handling performance of the vehicle can be enhanced significantly, and the minimum steer radius can be decreased by 20% which is significant improvement compared to the common level of main battle armoured vehicle around the world.

  3. Car following decisions under three visibility conditions and two speeds tested with a driving simulator.

    PubMed

    Broughton, Kathy L M; Switzer, Fred; Scott, Don

    2007-01-01

    The National Highway Traffic Safety Administration web site reports that rear-end collisions in the United States exceed 1.5 million per year, or approximately 23% of all vehicle crashes. Car following behavior and the decision-making habits of drivers seem fundamental to understanding how to avoid these rear-end crashes. The present research aimed to reveal factors that govern car following under conditions of reduced visibility. It employed a KQ-Vection high-fidelity driving simulator to measure the behavior of automobile drivers following a lead vehicle at 13.4 m/s (30 MPH) or 22.4 m/s (50 MPH) under three visibility conditions--clear or one of two densities of simulated fog. At the higher speed, fog conditions separated participants into a group that stayed within visible range of the lead car, even though the headway time violated the NHTSA recommendations for the speed involved, and another group that lagged beyond the visible range. Data were compared to the model of Van Winsum for car following (The human element in car following models. Transportation Research Part F 2, 1999). Contrast and image size measurements allowed comparison to a standard contrast sensitivity function and allowed estimation of the JND term in the Van Winsum model.

  4. Extended magnetohydrodynamic simulations of field reversed configuration formation and sustainment with rotating magnetic field current drive

    SciTech Connect

    Milroy, R. D.; Kim, C. C.; Sovinec, C. R.

    2010-06-15

    Three-dimensional simulations of field reversed configuration (FRC) formation and sustainment with rotating magnetic field (RMF) current drive have been performed with the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)]. The Hall term is a zeroth order effect with strong coupling between Fourier components, and recent enhancements to the NIMROD preconditioner allow much larger time steps than was previously possible. Boundary conditions to capture the effects of a finite length RMF antenna have been added, and simulations of FRC formation from a uniform background plasma have been performed with parameters relevant to the translation, confinement, and sustainment-upgrade experiment at the University of Washington [H. Y. Guo, A. L. Hoffman, and R. D. Milroy, Phys. Plasmas 14, 112502 (2007)]. The effects of both even-parity and odd-parity antennas have been investigated, and there is no evidence of a disruptive instability for either antenna type. It has been found that RMF effects extend considerably beyond the ends of the antenna, and that a large n=0 B{sub t}heta can develop in the open-field line region, producing a back torque opposing the RMF.

  5. Extended magnetohydrodynamic simulations of field reversed configuration formation and sustainment with rotating magnetic field current drive

    NASA Astrophysics Data System (ADS)

    Milroy, R. D.; Kim, C. C.; Sovinec, C. R.

    2010-06-01

    Three-dimensional simulations of field reversed configuration (FRC) formation and sustainment with rotating magnetic field (RMF) current drive have been performed with the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)]. The Hall term is a zeroth order effect with strong coupling between Fourier components, and recent enhancements to the NIMROD preconditioner allow much larger time steps than was previously possible. Boundary conditions to capture the effects of a finite length RMF antenna have been added, and simulations of FRC formation from a uniform background plasma have been performed with parameters relevant to the translation, confinement, and sustainment-upgrade experiment at the University of Washington [H. Y. Guo, A. L. Hoffman, and R. D. Milroy, Phys. Plasmas 14, 112502 (2007)]. The effects of both even-parity and odd-parity antennas have been investigated, and there is no evidence of a disruptive instability for either antenna type. It has been found that RMF effects extend considerably beyond the ends of the antenna, and that a large n =0 Bθ can develop in the open-field line region, producing a back torque opposing the RMF.

  6. Thermally Simulated Testing of a Direct-Drive Gas-Cooled Nuclear Reactor

    NASA Technical Reports Server (NTRS)

    Godfroy, Thomas; Bragg-Sitton, Shannon; VanDyke, Melissa

    2003-01-01

    This paper describes the concept and preliminary component testing of a gas-cooled, UN-fueled, pin-type reactor which uses He/Xe gas that goes directly into a recuperated Brayton system to produce electricity for nuclear electric propulsion. This Direct-Drive Gas-Cooled Reactor (DDG) is designed to be subcritical under water or wet-sand immersion in case of a launch accident. Because the gas-cooled reactor can directly drive the Brayton turbomachinery, it is possible to configure the system such that there are no external surfaces or pressure boundaries that are refractory metal, even though the gas delivered to the turbine is 1144 K. The He/Xe gas mixture is a good heat transport medium when flowing, and a good insulator when stagnant. Judicious use of stagnant cavities as insulating regions allows transport of the 1144-K gas while keeping all external surfaces below 900 K. At this temperature super-alloys (Hastelloy or Inconel) can be used instead of refractory metals. Super-alloys reduce the technology risk because they are easier to fabricate than refractory metals, we have a much more extensive knowledge base on their characteristics, and, because they have a greater resistance to oxidation, system testing is eased. The system is also relatively simple in its design: no additional coolant pumps, heat exchanger, or freeze-thaw systems are required. Key to success of this concept is a good knowledge of the heat transfer between the fuel pins and the gas, as well as the pressure drop through the system. This paper describes preliminary testing to obtain this key information, as well as experience in demonstrating electrical thermal simulation of reactor components and concepts.

  7. Modeling and Simulation of Control Actuation System with Fuzzy-PID Logic Controlled Brushless Motor Drives for Missiles Glider Applications.

    PubMed

    Muniraj, Murali; Arulmozhiyal, Ramaswamy

    2015-01-01

    A control actuation system has been used extensively in automotive, aerospace, and defense applications. The major challenges in modeling control actuation system are rise time, maximum peak to peak overshoot, and response to nonlinear system with percentage error. This paper addresses the challenges in modeling and real time implementation of control actuation system for missiles glider applications. As an alternative fuzzy-PID controller is proposed in BLDC motor drive followed by linkage mechanism to actuate fins in missiles and gliders. The proposed system will realize better rise time and less overshoot while operating in extreme nonlinear dynamic system conditions. A mathematical model of BLDC motor is derived in state space form. The complete control actuation system is modeled in MATLAB/Simulink environment and verified by performing simulation studies. A real time prototype of the control actuation is developed with dSPACE-1104 hardware controller and a detailed analysis is carried out to confirm the viability of the proposed system.

  8. Numerical Simulations of Hydrodynamic Instability Growth in Polar-Direct-Drive Implosions at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Shvydky, A.; Hohenberger, M.; Radha, P. B.; Rosenberg, M. J.; Craxton, R. S.; Goncharov, V. N.; Marozas, J. A.; Marshall, F. J.; McKenty, P. W.; Regan, S. P.; Sangster, T. C.

    2015-11-01

    Control of shell nonuniformities imprinted by the laser and amplified by hydrodynamic instabilities in the imploding target is critical to the success of polar-direct-drive ignition at the National Ignition Facility (NIF). To develop a platform for laser-imprint studies, hydrodynamic instability growth experiments in laser-driven implosions were performed on the NIF. The experiments used cone-in-shell targets with sinusoidal modulations of various wavelengths and amplitudes machined on the surface. Throughshell x-ray radiography was used to measure optical depth variations, from which the amplitudes of the shell areal-density modulations were extracted. Results of DRACO simulations of the growth of preimposed modulations and imprint-seeded perturbations will be presented and compared with the experimental data. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  9. Toking and Driving: Characteristics of Canadian University Students Who Drive after Cannabis Use--An Exploratory Pilot Study

    ERIC Educational Resources Information Center

    Fischer, Benedikt; Rodopoulos, Jenny; Rehm, Jurgen; Ivsins, Andrew

    2006-01-01

    Cannabis use is increasingly prevalent among young adults in Canada. Due to cannabis' impairment effects, driving under the influence of cannabis has recently developed into a traffic-safety concern, yet little is known about the specific circumstances and factors characterizing this behavior among young people. In this study, we interviewed a…

  10. Toking and Driving: Characteristics of Canadian University Students Who Drive after Cannabis Use--An Exploratory Pilot Study

    ERIC Educational Resources Information Center

    Fischer, Benedikt; Rodopoulos, Jenny; Rehm, Jurgen; Ivsins, Andrew

    2006-01-01

    Cannabis use is increasingly prevalent among young adults in Canada. Due to cannabis' impairment effects, driving under the influence of cannabis has recently developed into a traffic-safety concern, yet little is known about the specific circumstances and factors characterizing this behavior among young people. In this study, we interviewed a…

  11. Airblast Simulator Studies.

    DTIC Science & Technology

    1984-02-01

    predicted in steady state theory . 0 The Army has decided on the basis of other arguments that 10% blockage is acceptable for a large blast simulator. These...Proceedings, 28-30 April 1965, p. 259. 16. Sanal , M4., Lindberg, H.E. and Colton, J.D., "Simulation of Blast Waves with Tailored Explosive Charges", SRI

  12. Simulation studies of relativistic gyroklystron amplifiers

    SciTech Connect

    Saraph, G.P.; Anderson, J.P.; Lawson, W.; Granatstein, V.L.

    1997-12-31

    High power, pulsed gyroklystrons operating in the X, Ku, and Ka bands are being developed for driving future linear colliders. Various design aspects of two and three cavity, coaxial, relativistic gyroklystron systems are studied. Nonlinear simulations predict that over 40% efficiency, 45--50 dB gain, and 100--160 MW power levels are possible for the fundamental and second harmonic designs operating at 8.6, 17.1, and 35.0 GHz frequencies. Gyroklystron designs should also satisfy phase and frequency synchronization criteria for driving large accelerators. Small manufacturing tolerances can lead to 10--20 MHz changes in cold cavity frequencies. It is desirable to have some frequency tunability to compensate for this effect. It is shown that the desired frequency tunability can be achieved by making small adjustments in the axial magnetic field level. Effect of voltage pulse on the device efficiency and output phase is studied using time-dependent simulations. The pulse-shape plays an important role in determining phase stability. Advance design features such as radial coupling slots in the input and output cavities and dielectric loading are studied using HFSS simulations. An improved three cavity, Ku band design will be presented based on these features. In addition, a possible implementation scheme for energy recovery using a single-stage depressed collector will be presented. It is shown that the energy recovery could boost the net device efficiency above 50%.

  13. Helistat simulation studies

    NASA Technical Reports Server (NTRS)

    Tischler, M. B.; Ashkenas, I. L.

    1982-01-01

    An analysis of the flight dynamics and piloted control characteristics of the Helistat, a quadrotor heavy-lift airship, was completed using the HYBRDS airship simulation facility. The analysis covered the full operating flight envelope, including likely ranges of altitude, airspeed, sideslip, and loading variations. Particular areas of study were performance, trim, power requirements, linearized dynamics, handling qualities, and mooring operations. The key assumptions were: a rigid vehicle, no control system dynamics, fixed rotor and propeller RPM, and no ballonet dynamics. The nominal cruise speed for the H34 engines operating at 1275 HP was found to be 40-50 kts, depending on the loading condition. The maximum payload capability was calculated as 45,000 lbs for sea level-based operations. The crosswind capability in hover is 5-10 kts depending on the loading conditions, but this requires excessive roll angle due to the roll-to-translate control gearing. Sideslip angles of 110-135 degrees (wind from aft quarters) are critical for directional trim and stability, and should be avoided.

  14. Time-dependent simulation of lower hybrid current drive in JET discharges

    NASA Astrophysics Data System (ADS)

    Barbato, E.; Saveliev, A.; Voitsekhovitch, I.; Kirov, K.; Goniche, M.

    2014-12-01

    In this paper we report on simulations of lower hybrid current drive (LHCD) in JET closely comparing the simulation results to the available experimental data. The simulations are performed all over the relevant discharge duration by ASTRA. The LHCD module, FRTC, is based on a standard ray-tracing Fokker-Planck model. The purpose of the paper is to understand the present LHCD experiments issues within the limit of the LH linear propagation model. These issues are: (i) analysis of non-resonant collisional absorption (NRCA) of LH wave power in the main JET plasma during the current ramp-up phase and in steady-state (SS) scenarios, (ii) the lack of penetration of LHCD in high-density plasmas, (iii) current diffusion during the LHCD-assisted current ramp-up and (iv) assessment of the current profile alignment in JET SS discharges in the presence of LHCD. In recent experiments from FTU, JET and C_MOD, LHCD effects at high plasma density are either completely absent or less than expected. It has been shown, both in FTU and ALCATOR-C_MOD, that NRCA of LH wave power can be responsible for that. Indeed NRCA is estimated to be small in JET plasmas, at least in the main heating phase and therefore it is not expected to be responsible for the lack of penetration of LHW in high-density JET plasmas, however here we show for the first time that it can be effective during the early phase of the current ramp-up, when the plasma is still collisional. On the contrary it is suggested that the reduction of LHCD effects at high density may be attributed at least partially to the loss of accessibility of the n‖ spectrum effectively launched into the plasma. Furthermore it is shown that the linear propagation model provide very broad and stable LH current density profiles, with no need to include any non-linear spectral broadening. The current diffusion during the LHCD-assisted current ramp-up is investigated and a careful comparison between the simulated q-profiles and the measured

  15. Predicting DUI recidivism of male drunken driving: a prospective study of the impact of alcohol markers and previous drunken driving.

    PubMed

    Portman, M; Penttilä, A; Haukka, J; Eriksson, P; Alho, H; Kuoppasalmi, K

    2010-01-15

    The aim of the present study was to determine whether the alcohol biomarkers CDT, GGT, the biomarker gamma-CDT index and previous drunken driving contributed significantly to the prediction of DUI recidivism. The subjects consisted of two different samples of drivers, viz. drivers who were found to have a positive breath alcohol concentration during random breath testing surveys (n=237), and drunken drivers who were apprehended during ordinary police work (n=193). The drunken driving events were monitored using a data-base both retrospectively and prospectively. It was found that the biomarker index, gamma-CDT, emerged as a notable predictor of recidivism in the group of random breath tested drivers. Measurement of gamma-CDT and its impact on DUI recidivism has not to our knowledge been applied to random breath tested drivers before. The apprehended drunken drivers, on the other hand, did not show a significant relationship between gamma-CDT and DUI recidivism. However, in both groups of drivers it was found that a previous conviction for drunken driving strongly predicted DUI recidivism. More attention should be paid by both physicians and the police to the high risk of recidivism among those convicted of drunken driving. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  16. Simulations of Xenon Activation in Indirect Drive Exploding Pushers on NIF

    NASA Astrophysics Data System (ADS)

    Sepke, Scott M.; Hopkins, Laura Berzak; Cerjan, Charles; Marinak, Marty

    2014-10-01

    The indirect drive exploding pusher (IDEP) has proven to be a robust and well understood platform for experiments at the National Ignition Facility. We investigate the effect of adding xenon dopant in different concentrations to the DT gaseous fuel in IDEP capsules at various fill densities of experimental relevance -- 1.5-3 mg/cc -- through integrated capsule-hohlraum simulations using HYDRA. The primary metrics used to evaluate the performance are changes in neutron shock flash time and bang time, neutron yield, and the neutron time of flight temperature. In addition, the new post-processing code KUDU is used to explore the nuclear activation of the xenon dopant for natural xenon as well as pure Xe-124 and Xe-134 using the new post-processing code KUDU: a multiprocess (MPI), multithreaded (POSIX threads), and accelerator capable (CUDA and OpenACC) rate equation solver developed at Lawrence Livermore National Laboratory for radiochemistry modeling. This work (LLNL-ABS-656222) performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Factors influencing the probability of an incident at a junction: results from an interactive driving simulator.

    PubMed

    Alexander, Jennifer; Barham, Philip; Black, Ian

    2002-11-01

    Using data generated from a fixed-base interactive driving simulator, which was used to evaluate a driver decision aid, a model is built to predict the probability of an incident (i.e. an accident or a 'near miss') occurring as a result of a right-turn across left-hand traffic at an unsignalised junction. This can be considered to be the product of two separate probabilities, the first being the probability that the gap between a pair of vehicles in the traffic stream is accepted, and the second the probability that the time needed to cross the on-coming stream of traffic causes the time-to-collision with the nearest vehicle in this traffic stream to be less than a second. The model is developed from the results of experimental trials involving a sample of drivers, the majority of whom were aged 60 years or older, in order to demonstrate the effect of various parameters on these probabilities. The parameters considered include the size of the gap between successive vehicles, vehicle characteristics such as size, colour and velocity, driver characteristics such as age and sex, and both daytime and night-time conditions.

  18. Physiological investigation of automobile driver's activation index using simulated monotonous driving.

    PubMed

    Yamakoshi, T; Yamakoshi, K; Tanaka, S; Nogawa, M; Kusakabe, M; Kusumi, M; Tanida, K

    2004-01-01

    Monotonous automobile operation in our daily life may cause the lowering of what might be termed an activation state of the human body, resulting in an increased risk of an accident. We therefore propose to create a more suitable environment in-car so as to allow active operation of the vehicle, hopefully thus avoiding potentially dangerous situations during driving. In order to develop such an activation method as a final goal, we have firstly focused on the acquisition of physiological variables, including cardiovascular parameters, during presentation to the driver of a monotonous screen image, simulating autonomous travel of constant-speed on a motorway. Subsequently, we investigated the derivation of a driver's activation index. During the screen image presentation, a momentary electrical stimulation of about 1 second duration was involuntarily applied to a subject's shoulder to obtain a physiological response. We have successfully monitored various physiological variables during the image presentation, and results suggest that a peculiar pattern in the beat-by-beat change of blood pressure in response to the involuntary stimulus may be an appropriate, and feasible, index relevant to activation state.

  19. Study of Driving Fatigue Alleviation by Transcutaneous Acupoints Electrical Stimulations

    PubMed Central

    Wang, Fuwang; Wang, Hong

    2014-01-01

    Driving fatigue is more likely to bring serious safety trouble to traffic. Therefore, accurately and rapidly detecting driving fatigue state and alleviating fatigue are particularly important. In the present work, the electrical stimulation method stimulating the Láogóng point (劳宫PC8) of human body is proposed, which is used to alleviate the mental fatigue of drivers. The wavelet packet decomposition (WPD) is used to extract θ, α, and β subbands of drivers' electroencephalogram (EEG) signals. Performances of the two algorithms (θ + α)/(α + β) and θ/β are also assessed as possible indicators for fatigue detection. Finally, the differences between the drivers with electrical stimulation and normal driving are discussed. It is shown that stimulating the Láogóng point (劳宫PC8) using electrical stimulation method can alleviate driver fatigue effectively during longtime driving. PMID:25254242

  20. Belt Drives: A Case Study for Mathematics Students.

    ERIC Educational Resources Information Center

    Lee, D. H.; Galvin, S. R.

    1980-01-01

    An exercise in applied mathematics that focuses on belt drives that is suitable for senior secondary pupils is presented. Some comments on classroom use and student reactions to this lesson are included. (MP)