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Van Weverberg K.,Brookhaven National Laboratory | Van Weverberg K.,Catholic University of Louvain | Vogelmann A.M.,Brookhaven National Laboratory | Lin W.,Brookhaven National Laboratory | And 6 more authors.
Journal of the Atmospheric Sciences | Year: 2013

This paper presents a detailed analysis of convection-permitting cloud simulations, aimed at increasing the understanding of the role of parameterized cloud microphysics in the simulation of mesoscale convective systems (MCSs) in the tropical western Pacific (TWP). Simulations with three commonly used bulk microphysics parameterizations with varying complexity have been compared against satellite-retrieved cloud properties. An MCS identification and tracking algorithm was applied to the observations and the simulations to evaluate the number, spatial extent, and microphysical properties of individual cloud systems. Different from many previous studies, these individual cloud systems could be tracked over larger distances because of the large TWP domain studied. The analysis demonstrates that the simulation of MCSs is very sensitive to the parameterization of microphysical processes. The most crucial element was found to be the fall velocity of frozen condensate. Differences in this fall velocity between the experiments were more related to differences in particle number concentrations than to fall speed parameterization. Microphysics schemes that exhibit slow sedimentation rates for ice aloft experience a larger buildup of condensate in the upper troposphere. This leads to more numerous and/or larger MCSs with larger anvils. Mean surface precipitation was found to be overestimated and insensitive to the microphysical schemes employed in this study. In terms of the investigated properties, the performances of complex two-moment schemes were not superior to the simpler one-moment schemes, since explicit prediction of number concentration does not necessarily improve processes such as ice nucleation, the aggregation of ice crystals into snowflakes, and their sedimentation characteristics. © 2013 American Meteorological Society.


Thompson K.R.,University of Iowa | Johnson A.M.,University of Iowa | Emerson J.L.,University of Iowa | Dawson J.D.,University of Iowa | And 2 more authors.
Accident Analysis and Prevention | Year: 2012

Automobile driving is a safety-critical real-world example of multitasking. A variety of roadway and in-vehicle distracter tasks create information processing loads that compete for the neural resources needed to drive safely. Drivers with mind and brain aging may be particularly susceptible to distraction due to waning cognitive resources and control over attention. This study examined distracted driving performance in an instrumented vehicle (IV) in 86 elderly (mean = 72.5 years, SD = 5.0 years) and 51 middle-aged drivers (mean = 53.7 years, SD = 9.3 year) under a concurrent auditory-verbal processing load created by the Paced Auditory Serial Addition Task (PASAT). Compared to baseline (no-task) driving performance, distraction was associated with reduced steering control in both groups, with middle-aged drivers showing a greater increase in steering variability. The elderly drove slower and showed decreased speed variability during distraction compared to middle-aged drivers. They also tended to "freeze up", spending significantly more time holding the gas pedal steady, another tactic that may mitigate time pressured integration and control of information, thereby freeing mental resources to maintain situation awareness. While 39% of elderly and 43% of middle-aged drivers committed significantly more driving safety errors during distraction, 28% and 18%, respectively, actually improved, compatible with allocation of attention resources to safety critical tasks under a cognitive load. © 2011 Elsevier Ltd. All rights reserved.


Tatham A.J.,University of California at San Diego | Boer E.R.,Entropy Control Inc. | Boer E.R.,Technical University of Delft | Rosen P.N.,University of California at San Diego | And 5 more authors.
American Journal of Ophthalmology | Year: 2014

Methods: Setting: Hamilton Glaucoma Center, University of California San Diego.Purpose: To examine the relationship between glaucomatous structural damage and ability to divide attention during simulated driving.Patient Population: Total of 158 subjects from the Diagnostic Innovations in Glaucoma Study, including 82 with glaucoma and 76 similarly aged controls.Observation Procedure: Ability to divide attention was investigated by measuring reaction times to peripheral stimuli (at low, medium, or high contrast) while concomitantly performing a central driving task (car following or curve negotiation). All subjects had standard automated perimetry (SAP) and optical coherence tomography was used to measure retinal nerve fiber layer (RNFL) thickness. Cognitive ability was assessed using the Montreal Cognitive Assessment and subjects completed a driving history questionnaire.Main Outcome Measures: Reaction times to the driving simulator divided attention task.Results: The mean reaction times to the low-contrast stimulus were 1.05 s and 0.64 s in glaucoma and controls, respectively, during curve negotiation (P < .001), and 1.19 s and 0.77 s (P = .025), respectively, during car following. There was a nonlinear relationship between reaction times and RNFL thickness in the better eye. RNFL thickness remained significantly associated with reaction times even after adjusting for age, SAP mean deviation in the better eye, cognitive ability, and central driving task performance.Conclusion: Although worse SAP sensitivity was associated with worse ability to divide attention, RNFL thickness measurements provided additional information. Information from structural tests may improve our ability to determine which patients are likely to have problems performing daily activities, such as driving. © 2014 by Elsevier Inc. All rights reserved. DESIGN: Cross-sectional observational study.


Abbink D.A.,Technical University of Delft | Mulder M.,Technical University of Delft | Boer E.R.,Entropy Control Inc.
Cognition, Technology and Work | Year: 2012

Literature points to persistent issues in human-automation interaction, which are caused either when the human does not understand the automation or when the automation does not understand the human. Design guidelines for human-automation interaction aim to avoid such issues and commonly agree that the human should have continuous interaction and communication with the automation system and its authority level and should retain final authority. This paper argues that haptic shared control is a promising approach to meet the commonly voiced design guidelines for human-automation interaction, especially for automotive applications. The goal of the paper is to provide evidence for this statement, by discussing several realizations of haptic shared control found in literature. We show that literature provides ample experimental evidence that haptic shared control can lead to short-term performance benefits (e. g., faster and more accurate vehicle control; lower levels of control effort; reduced demand for visual attention). We conclude that although the continuous intuitive physical interaction inherent in haptic shared control is expected to reduce long-term issues with human-automation interaction, little experimental evidence for this is provided. Therefore, future research on haptic shared control should focus more on issues related to long-term use such as trust, overreliance, dependency on the system, and retention of skills. © 2011 The Author(s).


Tatham A.J.,University of California at San Diego | Boer E.R.,Technical University of Delft | Rosen P.N.,University of California at San Diego | Della Penna M.,Entropy Control Inc. | And 4 more authors.
American Journal of Ophthalmology | Year: 2014

Purpose: To examine the relationship between glaucomatous structural damage and ability to divide attention during simulated driving. Design: Cross-sectional observational study. Methods: setting : Hamilton Glaucoma Center, University of California San Diego. patient population : Total of 158 subjects from the Diagnostic Innovations in Glaucoma Study, including 82 with glaucoma and 76 similarly aged controls. observation procedure : Ability to divide attention was investigated by measuring reaction times to peripheral stimuli (at low, medium, or high contrast) while concomitantly performing a central driving task (car following or curve negotiation). All subjects had standard automated perimetry (SAP) and optical coherence tomography was used to measure retinal nerve fiber layer (RNFL) thickness. Cognitive ability was assessed using the Montreal Cognitive Assessment and subjects completed a driving history questionnaire. main outcome measures : Reaction times to the driving simulator divided attention task. Results: The mean reaction times to the low-contrast stimulus were 1.05 s and 0.64 s in glaucoma and controls, respectively, during curve negotiation (P < .001), and 1.19 s and 0.77 s (P = .025), respectively, during car following. There was a nonlinear relationship between reaction times and RNFL thickness in the better eye. RNFL thickness remained significantly associated with reaction times even after adjusting for age, SAP mean deviation in the better eye, cognitive ability, and central driving task performance. Conclusions: Although worse SAP sensitivity was associated with worse ability to divide attention, RNFL thickness measurements provided additional information. Information from structural tests may improve our ability to determine which patients are likely to have problems performing daily activities, such as driving. © 2014 Elsevier Inc. All rights reserved.


Abbink D.A.,Technical University of Delft | Mulder M.,Technical University of Delft | Van Der Helm F.C.T.,Technical University of Delft | Boer E.R.,Entropy Control Inc.
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

In previous research, a driver support system that uses continuous haptic feedback on the gas pedal to inform drivers of the separation to the lead vehicle was developed. Although haptic feedback has been previously shown to be beneficial, the influence of the underlying biomechanical properties of the driver on the effectiveness of haptic feedback is largely unknown. The goal of this paper is to experimentally determine the biomechanical properties of the ankle-foot complex (i.e., the admittance) while performing a car-following task, thereby separating driver responses to visual feedback from those to designed haptic feedback. An experiment was conducted in a simplified fixed-base driving simulator, where ten participants were instructed to follow a lead vehicle, with and without the support of haptic feedback. During the experiment, the lead vehicle velocity was perturbed, and small stochastic torque perturbations were applied to the pedal. Both perturbations were separated in the frequency domain to allow the simultaneous estimation of frequency response functions of both the car-following control behavior and the biomechanical admittance. For comparison to previous experiments, the admittance was also estimated during three classical motion control tasks (resist forces, relax, and give way to forces). The main experimental hypotheses were that, first, the haptic feedback would encourage drivers to adopt a give way to force task, resulting in larger admittance compared with other tasks and, second, drivers needed less control effort to realize the same car-following performance. Time-and frequency-domain analyses provided evidence for both hypotheses. The developed methodology allows quantification of the range of admittances that a limb can adopt during vehicle control or while performing a variety of motion control tasks. It thereby allows detailed computational driver modeling and provides valuable information on how to design and evaluate continuous haptic feedback systems. © 2011 IEEE.


A target-travel-path generating circuit calculates a target travel path along which a controlled object can travel in the future from a current controlled object position. An ideal-control-signal calculating circuit calculates a control profile to travel along the target travel path, and a difference calculating circuit calculates a difference between an ideal control magnitude and a current control magnitude. A controller controls an operation system based on a magnitude of the difference to assist a control operation and a control-operation-state of an operator, an environment-state, and a required operation-precision. The operator receives assistance corresponding to the magnitude of the difference from an ideal control state, the control-operation-state, the environment-state, and the required operation-precision. An outputted control-operation assistance control is suitable for conditions that characterize the operator state, the environment, and the controlled object.


Patent
Nissan Motor Co., Entropy Control Inc. and Technical University of Delft | Date: 2012-12-26

A driving-operation assisting device that assists a vehicle operation, comprising a vehicle-operation-state detecting unit that detects information about an operation state of the operator, an environment-state detecting unit that detects information about a vehicle operation environment on a periphery of an operation target object, an ideal-control-path generating unit that generates an ideal control path of the operation target object, an ideal-control-signal calculating unit that calculates, as an ideal control signal, a control history of an operation system for the operation target object to operate along the ideal control path, a difference calculating unit that calculates a difference between the ideal control signal calculated by the ideal-control-signal calculating unit and the information about the vehicle operation state detected by the vehicle-operation-state detecting unit, an operation-system assistance controller that controls the operation system based on a magnitude of the difference calculated by the difference calculating unit to execute control for assisting an operation of the operator for the operation system, an operation-precision estimating unit that estimates an accuracy required for the vehicle operation of the operation target object, whereinthe operation-system assistance controller increases a control level of the operation system as the accuracy estimated by the operation-precision estimating unit is higher.


PubMed | University of California at San Diego, Technical University of Delft and Entropy Control Inc.
Type: Clinical Trial | Journal: American journal of ophthalmology | Year: 2014

To examine the relationship between glaucomatous structural damage and ability to divide attention during simulated driving.Cross-sectional observational study.Hamilton Glaucoma Center, University of California San Diego.Total of 158 subjects from the Diagnostic Innovations in Glaucoma Study, including 82 with glaucoma and 76 similarly aged controls.Ability to divide attention was investigated by measuring reaction times to peripheral stimuli (at low, medium, or high contrast) while concomitantly performing a central driving task (car following or curve negotiation). All subjects had standard automated perimetry (SAP) and optical coherence tomography was used to measure retinal nerve fiber layer (RNFL) thickness. Cognitive ability was assessed using the Montreal Cognitive Assessment and subjects completed a driving history questionnaire.Reaction times to the driving simulator divided attention task.The mean reaction times to the low-contrast stimulus were 1.05 s and 0.64 s in glaucoma and controls, respectively, during curve negotiation (P < .001), and 1.19 s and 0.77 s (P = .025), respectively, during car following. There was a nonlinear relationship between reaction times and RNFL thickness in the better eye. RNFL thickness remained significantly associated with reaction times even after adjusting for age, SAP mean deviation in the better eye, cognitive ability, and central driving task performance.Although worse SAP sensitivity was associated with worse ability to divide attention, RNFL thickness measurements provided additional information. Information from structural tests may improve our ability to determine which patients are likely to have problems performing daily activities, such as driving.


PubMed | Entropy Control Inc.
Type: | Journal: Proceedings of the ... International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle Design | Year: 2013

Negotiating intersections is a complex driving task that is particularly difficult for older drivers. This task requires accurate coordination of multiple driving subtasks, placing high demands on perception, attention and motor control that are known to decline with age. We analyzed intersection negotiation behavior in an instrumented vehicle and found striking differences in how drivers of different ages synchronize speed and heading control when turning right. The older drivers performed most of their steering while standing still instead of while accelerating as younger drivers do. This shift from parallel to serial control is a compensatory solution that drivers employ in response to age related decline in perception, cognition, and motor control abilities. Serialization of turning at an intersection reduces attentional demands largely by eliminating the need to switch attention between different driving sub-tasks.

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