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Papers by Rainer Guttkuhn

Research paper thumbnail of Automatic Microsleep Detection by Artificial Neural Networks and Fuzzy Context Interpretations

Journal of Sleep Research

Research paper thumbnail of Sleep Pattern in Workers with Irregular and Unpredictable Work Hours

Journal of Sleep Research

Research paper thumbnail of Circadian Allertness Simulator for Fatigue Risk Assessment in Transportation: Application to Reduce Frequency and Severity of Truck Accidents

Aviation Space and Environmental Medicine

The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk ... more The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk of diminished alertness at work. Applications of CAS include assessment of operational fatigue risk, work schedule optimization, and fatigue-related accident investigation. Based on the documented work schedules of employees, sleep and alertness patterns are estimated and a cumulative fatigue score is calculated. The risk assessment algorithms are based on physiological sleep/wake principles including homeostatic and circadian processes. The free parameters of the algorithms were optimized using over 10,000 d of sleep and alertness data sets collected from transportation workers performing their regular jobs. The validity and applicability of the CAS fatigue score was then tested using work/rest and accident data from three trucking operations. Heavy truck drivers involved in DOT-recordable or high-cost accidents were found to have significantly higher CAS fatigue risk scores than accide...

Research paper thumbnail of Technologies for the Monitoring and Prevention of Driver Fatigue

A series of driving simulation pilot studies on various technologies for alertness monitoring (he... more A series of driving simulation pilot studies on various technologies for alertness monitoring (head position sensor, eye-gaze system), fitness-for-duty testing (two pupil-based systems), and alertness promotion (in-seat vibration system) has been conducted in Circadian Technologies' Alertness Testbed. The results indicate that, all tested technologies show promise for monitoring/testing or preventing driver fatigue, respectively. However, particularly for fatigue monitoring, no single measure alone may be sensitive and reliable enough to quantify driver fatigue. Since alertness is a complex phenomenon, a multi-parametric approach needs to be used. Such a multi-sensor approach imposes challenges for online data interpretation. We suggest using a neural-fuzzy hybrid system for the automatic assessment of complex data streams for driver fatigue. The final system output can then be used to trigger the activation of alertness countermeasures.

Research paper thumbnail of Computerized Fatigue Analysis for Work Schedule Evaluation

Research paper thumbnail of Fatigue Countermeasure Rebound: Temporary Alertness Gain from Caffeinated Chewing Gum Repaid as Excessive Sleepiness after Countermeasure Cessation

Research paper thumbnail of Fatigue Accident/Incident Causation Testing System (FACTS)

Research paper thumbnail of Relationship between Marine Pilot Complement and Pilot Fatigue Risk during Tanker Vessel Movements: Optimizing Staffing Efficiency and Safety

Research paper thumbnail of Circadian alertness simulator for fatigue risk assessment in transportation: application to reduce frequency and severity of truck accidents

Aviation, space, and environmental medicine, 2004

The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk ... more The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk of diminished alertness at work. Applications of CAS include assessment of operational fatigue risk, work schedule optimization, and fatigue-related accident investigation. Based on the documented work schedules of employees, sleep and alertness patterns are estimated and a cumulative fatigue score is calculated. The risk assessment algorithms are based on physiological sleep/wake principles including homeostatic and circadian processes. The free parameters of the algorithms were optimized using over 10,000 d of sleep and alertness data sets collected from transportation workers performing their regular jobs. The validity and applicability of the CAS fatigue score was then tested using work/rest and accident data from three trucking operations. Heavy truck drivers involved in DOT-recordable or high-cost accidents were found to have significantly higher CAS fatigue risk scores than accide...

Research paper thumbnail of Human fatigue risk simulations in 24/7 operations

Proceedings of the 2003 International Conference on Machine Learning and Cybernetics (IEEE Cat. No.03EX693), 2003

A Circadian Alertness Simulator (CAS) is presented as an interactive tool for assessing sleep beh... more A Circadian Alertness Simulator (CAS) is presented as an interactive tool for assessing sleep behavior and fatigue risk in 24/7 operations. The simulation model uses as input sleep-wake data and information about individual sleep characteristics (short vs. long sleeper, morning type vs. evening type, napper vs. non-napper). The validation of the CAS model was based on a figure of merit function reflecting the model's ability to minimize the difference between reported and predicted sleep data. The purpose of the alertness model is the assessment of work schedules in terms of fatigue risk.

Research paper thumbnail of Expert System for Simulating and Predicting Sleep and Alertness Patterns

Lecture Notes in Computer Science, 2003

The Expert System "Circadian Alertness Simulator" predicts employee sleep and alertness patterns ... more The Expert System "Circadian Alertness Simulator" predicts employee sleep and alertness patterns in 24/7-work environments using rules of complex interactions between human physiology, operational demands and environmental conditions. The system can be tailored to the specific biological characteristics of individuals as well as to specific characteristics of groups of individuals (e.g., transportation employees). This adaptation capability of the system is achieved through a built-in learning module, which allows transferring information from actual data on sleep-wake-work patterns and individual sleep characteristics into an internal knowledge database. The expert system can be used as a fatigue management tool for minimizing the detrimental biological effects of 24-hour operations by providing feedback and advice for work scheduling and/or individualspecific lifestyle training. Consequently, it can help reduce accident risk and human-related costs of the 24/7 economy.

Research paper thumbnail of Simulation planning and rostering: a discrete event simulation for the crew assignment process in north american freight railroads

This paper introduces a discrete event simulation for crew assignments and crew movements as a re... more This paper introduces a discrete event simulation for crew assignments and crew movements as a result of train traffic, labor rules, government regulations and optional crew schedules. The software is part of a schedule development system, FRCOS (Freight Rail Crew Optimization System), that was co-developed by Canadian National (CN) Rail and Circadian Technologies, Inc. The simulation allows verification of the impact of changes to trainflow, labor rules or government regulations on the overall operational efficiency of how crews are called to work. The system helps to evaluate changes to current crew assignments and can test new crew assignment scenarios such as crew schedules. Potential problems can be detected before the actual implementation, saving unnecessary costs. The software is also used to assess the impact of traffic changes on existing crew schedules in order to implement reactive corrections to these schedules.

Research paper thumbnail of Customer Relations Management: Service Operations: Using Simulation to Approximate Subgradients of Convex Performance Measures In Service Systems

Proceedings of the 35th …, 2003

We study the problem of approximating a subgradient of a convex (or concave) discrete function th... more We study the problem of approximating a subgradient of a convex (or concave) discrete function that is evaluated via simulation. This problem arises, for instance, in optimization problems such as finding the minimal cost staff schedule in a call center subject to a service level constraint. There, subgradient information can be used to significantly reduce the search space. The problem of approximating subgradients is closely related to the one of approximating gradients and we suggest and compare how three existing methods for computing gradients via simulation, i.e., finite differences, the likelihood ratio method and infinitesimal perturbation analysis, can be applied to approximate subgradients when the variables are discrete. We provide a computational study to highlight the properties of each approach.

Research paper thumbnail of Automatic detection of microsleep events using a neuro-fuzzy hybrid system

Research paper thumbnail of Automatic Microsleep Detection by Artificial Neural Networks and Fuzzy Context Interpretations

Journal of Sleep Research

Research paper thumbnail of Sleep Pattern in Workers with Irregular and Unpredictable Work Hours

Journal of Sleep Research

Research paper thumbnail of Circadian Allertness Simulator for Fatigue Risk Assessment in Transportation: Application to Reduce Frequency and Severity of Truck Accidents

Aviation Space and Environmental Medicine

The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk ... more The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk of diminished alertness at work. Applications of CAS include assessment of operational fatigue risk, work schedule optimization, and fatigue-related accident investigation. Based on the documented work schedules of employees, sleep and alertness patterns are estimated and a cumulative fatigue score is calculated. The risk assessment algorithms are based on physiological sleep/wake principles including homeostatic and circadian processes. The free parameters of the algorithms were optimized using over 10,000 d of sleep and alertness data sets collected from transportation workers performing their regular jobs. The validity and applicability of the CAS fatigue score was then tested using work/rest and accident data from three trucking operations. Heavy truck drivers involved in DOT-recordable or high-cost accidents were found to have significantly higher CAS fatigue risk scores than accide...

Research paper thumbnail of Technologies for the Monitoring and Prevention of Driver Fatigue

A series of driving simulation pilot studies on various technologies for alertness monitoring (he... more A series of driving simulation pilot studies on various technologies for alertness monitoring (head position sensor, eye-gaze system), fitness-for-duty testing (two pupil-based systems), and alertness promotion (in-seat vibration system) has been conducted in Circadian Technologies' Alertness Testbed. The results indicate that, all tested technologies show promise for monitoring/testing or preventing driver fatigue, respectively. However, particularly for fatigue monitoring, no single measure alone may be sensitive and reliable enough to quantify driver fatigue. Since alertness is a complex phenomenon, a multi-parametric approach needs to be used. Such a multi-sensor approach imposes challenges for online data interpretation. We suggest using a neural-fuzzy hybrid system for the automatic assessment of complex data streams for driver fatigue. The final system output can then be used to trigger the activation of alertness countermeasures.

Research paper thumbnail of Computerized Fatigue Analysis for Work Schedule Evaluation

Research paper thumbnail of Fatigue Countermeasure Rebound: Temporary Alertness Gain from Caffeinated Chewing Gum Repaid as Excessive Sleepiness after Countermeasure Cessation

Research paper thumbnail of Fatigue Accident/Incident Causation Testing System (FACTS)

Research paper thumbnail of Relationship between Marine Pilot Complement and Pilot Fatigue Risk during Tanker Vessel Movements: Optimizing Staffing Efficiency and Safety

Research paper thumbnail of Circadian alertness simulator for fatigue risk assessment in transportation: application to reduce frequency and severity of truck accidents

Aviation, space, and environmental medicine, 2004

The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk ... more The Circadian Alertness Simulator (CAS) was developed as a practical tool for assessing the risk of diminished alertness at work. Applications of CAS include assessment of operational fatigue risk, work schedule optimization, and fatigue-related accident investigation. Based on the documented work schedules of employees, sleep and alertness patterns are estimated and a cumulative fatigue score is calculated. The risk assessment algorithms are based on physiological sleep/wake principles including homeostatic and circadian processes. The free parameters of the algorithms were optimized using over 10,000 d of sleep and alertness data sets collected from transportation workers performing their regular jobs. The validity and applicability of the CAS fatigue score was then tested using work/rest and accident data from three trucking operations. Heavy truck drivers involved in DOT-recordable or high-cost accidents were found to have significantly higher CAS fatigue risk scores than accide...

Research paper thumbnail of Human fatigue risk simulations in 24/7 operations

Proceedings of the 2003 International Conference on Machine Learning and Cybernetics (IEEE Cat. No.03EX693), 2003

A Circadian Alertness Simulator (CAS) is presented as an interactive tool for assessing sleep beh... more A Circadian Alertness Simulator (CAS) is presented as an interactive tool for assessing sleep behavior and fatigue risk in 24/7 operations. The simulation model uses as input sleep-wake data and information about individual sleep characteristics (short vs. long sleeper, morning type vs. evening type, napper vs. non-napper). The validation of the CAS model was based on a figure of merit function reflecting the model's ability to minimize the difference between reported and predicted sleep data. The purpose of the alertness model is the assessment of work schedules in terms of fatigue risk.

Research paper thumbnail of Expert System for Simulating and Predicting Sleep and Alertness Patterns

Lecture Notes in Computer Science, 2003

The Expert System "Circadian Alertness Simulator" predicts employee sleep and alertness patterns ... more The Expert System "Circadian Alertness Simulator" predicts employee sleep and alertness patterns in 24/7-work environments using rules of complex interactions between human physiology, operational demands and environmental conditions. The system can be tailored to the specific biological characteristics of individuals as well as to specific characteristics of groups of individuals (e.g., transportation employees). This adaptation capability of the system is achieved through a built-in learning module, which allows transferring information from actual data on sleep-wake-work patterns and individual sleep characteristics into an internal knowledge database. The expert system can be used as a fatigue management tool for minimizing the detrimental biological effects of 24-hour operations by providing feedback and advice for work scheduling and/or individualspecific lifestyle training. Consequently, it can help reduce accident risk and human-related costs of the 24/7 economy.

Research paper thumbnail of Simulation planning and rostering: a discrete event simulation for the crew assignment process in north american freight railroads

This paper introduces a discrete event simulation for crew assignments and crew movements as a re... more This paper introduces a discrete event simulation for crew assignments and crew movements as a result of train traffic, labor rules, government regulations and optional crew schedules. The software is part of a schedule development system, FRCOS (Freight Rail Crew Optimization System), that was co-developed by Canadian National (CN) Rail and Circadian Technologies, Inc. The simulation allows verification of the impact of changes to trainflow, labor rules or government regulations on the overall operational efficiency of how crews are called to work. The system helps to evaluate changes to current crew assignments and can test new crew assignment scenarios such as crew schedules. Potential problems can be detected before the actual implementation, saving unnecessary costs. The software is also used to assess the impact of traffic changes on existing crew schedules in order to implement reactive corrections to these schedules.

Research paper thumbnail of Customer Relations Management: Service Operations: Using Simulation to Approximate Subgradients of Convex Performance Measures In Service Systems

Proceedings of the 35th …, 2003

We study the problem of approximating a subgradient of a convex (or concave) discrete function th... more We study the problem of approximating a subgradient of a convex (or concave) discrete function that is evaluated via simulation. This problem arises, for instance, in optimization problems such as finding the minimal cost staff schedule in a call center subject to a service level constraint. There, subgradient information can be used to significantly reduce the search space. The problem of approximating subgradients is closely related to the one of approximating gradients and we suggest and compare how three existing methods for computing gradients via simulation, i.e., finite differences, the likelihood ratio method and infinitesimal perturbation analysis, can be applied to approximate subgradients when the variables are discrete. We provide a computational study to highlight the properties of each approach.

Research paper thumbnail of Automatic detection of microsleep events using a neuro-fuzzy hybrid system