Driver fatigue during extended rail operations

OBJECTIVES: Relay is an effective mode of freight transportation within Australia. Relay requires two crews to drive the train continuously from one specified destination to another and return with crews working in alternating shifts. The aim of the current investigation was to assess fatigue levels during extended relay operations. METHODS: Nine drivers participated and data were collected from 16 four-day trips. Fatigue was assessed objectively and subjectively prior to and following each trip and before and after each 8h shift. RESULTS: Analyses revealed a trend for elevated fatigue at the end of each shift. Designated 8h rest periods appeared sufficient to reduce fatigue to levels recorded prior to departure and prevent accumulation of fatigue across the trip. CONCLUSIONS: Drivers seemed to cope well with the 8h rotating sleep/wake regime. While fatigue did not observably accumulate, it is possible that operational measures may better reflect fatigue experienced over the course of each trip.     

Pinching forces sustained during lens polishing operations

A typical spectacle lens-polishing operation was simulated in the laboratory. Forearm flexor, smoothed-rectified EMG signals were used to estimate pinching forces used in the operation. Levels of forces produced were very large, near maximum, reaching values of up to 108 N. Largest forces were obtained at the neutral wrist position. Varying various conditions of the task, indicated that using a straight arm, subjectively low pressure and a zig-zag polishing method significantly reduced the pinching force levels. In addition, wetting the lens and providing visual feedback to the subject also tended to reduce pinching force levels.     

Empirical analysis of safety-critical anomalies during operations

Analysis of anomalies that occur during operations is an important means of improving the quality of current and future software. Although the benefits of anomaly analysis of operational software are widely recognized, there has been relatively little research on anomaly analysis of safety-critical systems. In particular, patterns of software anomaly data for operational, safety-critical systems are not well understood. We present the results of a pilot study using orthogonal defect classification (ODC) to analyze nearly two hundred such anomalies on seven spacecraft systems. These data show several unexpected classification patterns such as the causal role of difficulties accessing or delivering data, of hardware degradation, and of rare events. The anomalies often revealed latent software requirements that were essential for robust, correct operation of the system. The anomalies also caused changes to documentation and to operational procedures to prevent the same anomalous situations from recurring. Feedback from operational anomaly reports helped measure the accuracy of assumptions about operational profiles, identified unexpected dependencies among embedded software and their systems and environment, and indicated needed improvements to the software, the development process, and the operational procedures. The results indicate that, for long-lived, critical systems, analysis of the most severe anomalies can be a useful mechanism both for maintaining safer, deployed systems and for building safer, similar systems in the future.     

Alveolar flooding: a computer simulation

A validated computer simulation of pulmonary microvascular exchange (J.L. Bert and K.L. Pinder, Microvasc. Res., 27 (1984) 51-70) has been extended to include exchange with the air space (alveoli). Equations which hypothetically describe characteristics associated with this additional compartment and the exchange of both fluid and plasma proteins between the lung tissue and the alveolar space are presented. These are incorporated into the simulation which has been used to predict the behavior of the pulmonary microvascular exchange system including alveolar flooding. The predicted trends associated with alveolar flooding are reasonable. However, due to the lack of specific experimental or clinical findings, the simulation remains essentially unvalidated. The effect on alveolar flooding and interstitial edema of the parameters associated with the additional relationships is presented and discussed. Primarily, results for perturbations in circulatory pressure are presented. Additionally, changes in permeability characteristics are shown and discussed.     

Semantic flooding

Classifications are trees where links between nodes codify the fact that a node lower in the hierarchy describes a topic (and contains documents about this topic) which is more specific than the topic of the node one level above. In turn, multiple classifications can be connected by semantic links which represent mappings among them and which can be computed, e.g. by ontology matching. In this paper, we describe how these two types of links can be used to define a semantic overlay network which can cover any number of peers and which can be flooded to perform a semantic search on documents, i.e. to perform semantic flooding. We have evaluated our approach by simulating networks of 10, 100, 1,000 and 10,000 peers containing classifications which are fragments of the DMoz web directory. The results are promising and show that, in our approach, only a relatively small number of peers needs to be queried in order to achieve high accuracy.     

Motion sickness in passenger vehicles during test track operations

Abstract

As automation transforms drivers into passengers, the deployment of automated vehicles (AVs) has the potential to greatly increase the incidence of motion sickness. A study was conducted to quantify motion sickness response of front-seat passengers performing ecologically relevant passenger activities during conditions consistent with driving on public roadways. Fifty-two adults with a large range of self-reported levels of motion sickness susceptibility and age participated in data collection on a closed test track in a passenger sedan. Motion sickness ratings increased with task vs. no-task and moderate vs. low acceleration test conditions. Increased motion sickness susceptibility was associated with higher motion sickness ratings. In comparison to older participants (age?>?60), younger participants (age?<?60) experienced increased motion sickness. This is the first in-vehicle study that systematically compared normative passenger activities and acceleration magnitudes typical of normative driving conditions on motion sickness response for a large, diverse sample of passengers, enabling the exploration of the effects of covariates.

Practitioner summary: The data demonstrate that a relatively large range of motion sickness response can be expected to result from passengers performing visual tasks in passenger vehicles. Measurement and modelling efforts should seek to elucidate relationships among the factors contributing to motion sickness for the purpose of informing and prioritising future countermeasures for automated vehicles (AVs).

Abbreviations: AV(S): automated vehicles; BMI: body mass index; BVP: blood volume pulse; EDA: electrodermal activity; FMS: fast motion sickness scale; GPS: global positioning system; IMU: inertial measurement unit; ISO: International Organization for Standardization; MISC: misery scale; MSDV: motion sickness dose value; NDS: naturalistic driving study; SAE: Society of Automotive Engineers International; UMTRI: The University of Michigan Transportation Research Institute

Key Aspect of Research: Motion sickness may be an important barrier to widespread adoption of automated vehicles @UMTRI.     

Nonlinear stress analysis of offshore pipelines during pickup operations

This paper presents a method of analyzing the stresses in a submarine pipeline as it is picked up off the sea floor by barge davits. A nonlinear large-deflection analysis is used and the pipeline is modeled as a series of finite beam segments from the ocean bottom on up. The governing equations are derived and the pipeline configuration satisfying known boundary conditions is determined by an initial-value approach using an iterativetype technique. Boundary conditions at the mudline are identified by modeling the pipeline resting on the ocean bed as a semi-infinite tensioned beam on an elastic foundation. The effects of a nonlinear stress-strain curve for the pipe material are included and both Ramberg-Osgood and Hutchinson formulations are considered. With the technique suggested, any given pickup procedure can be analyzed or a reliable procedure can be developed based on a given allowable pipe stress level and any desired improvement in the final configuration and/or stress levels may be achieved by a variation of the parameters involved. A practical example is examined to demonstrate the applicability of the analysis presented, which should provide a useful tool in either judging or developing a pickup procedure.     

Train drivers' sleep and alertness during short relay operations

Within Australia, there has been a recent expansion of relay working operations. To address concerns about the amount of sleep obtained by drivers in relay vans, and potential deficits in alertness associated with relay work, the current study assessed the sleep behaviour and alertness of 15 train drivers working short (<48 h) relay operations. In total, drivers obtained 8-12h of sleep during the relay trip (which took approx 40 h). Overall, they reported that they felt more alert following each sleep period. Drivers were able to sustain attention during the 10-min vigilance tasks administered before and after each shift. These findings suggest that the amount of sleep obtained in crew vans during short relay operations is sufficient to maintain alertness during the trip. They also emphasise the importance of scheduling shifts to maximise the number of sleep opportunities that occur between 2200 and 0700 h.     

Six-degree-of-freedom whole-body vibration exposure levels during routine skidder operations

This research focuses on quantifying six-degree-of-freedom (6-DOF) whole-body vibration (WBV) exposure levels that occur in Northern Ontario skidders during routine field operating tasks. 6-DOF vibration running root-mean-square (RMS) acceleration levels at the operator/seat interface were determined for eight skidders while driving loaded, driving unloaded, picking up a load, dropping off a load and ploughing logs under field operating conditions. The acceleration data were weighted in accordance with ISO 2631–1:1997 and evaluated for both health and comfort outcomes. The mean running RMS weighted translational and rotational accelerations all exceeded 0.36 m/s² and 0.14 rad/s². The greatest average accelerations occurred while driving unloaded with this condition displaying translational vibration total values (VTV) that exceeded the upper limit of the ISO 2631–1:1997 health caution zone within an average of 2.3 h. Utilizing 6-DOF VTV, virtually all operating conditions would be designated as uncomfortable.

Statement of Relevance: This study provides one of the most comprehensive reports on vibration exposures in seated vehicle operators. The results are geared towards ergonomists with discussions on health effects and measurement concerns, while providing the raw vibration exposure data that will be useful to vehicle, component and vibration sensor designers.     

Neck kinematics and muscle activity during mobile device operations

Neck pain is a significant health problem due to its high incident rates and economic costs. Increased use of touch screen mobile devices is becoming pervasive in the modern society and may further influence this already prevalent health problem. However, our current understanding of the cervical spine biomechanics during the operation of touch screen mobile devices is very limited. This study evaluated the neck extensor muscle activities and the kinematics of the cervical spine during the operation of a touch screen tablet and a smart phone. Three-variables, DEVICE, LOCATION and TASK were treated as the independent variables. NASA TLX revealed that “Gaming” was the least difficult task and “Typing” was the most difficult task. Participants of this study maintained significantly deeper neck flexion when operating a smart phone (44.7°), with the mobile devices set on a table (46.4°), and while performing a “Typing” task (45.6°). Lower levels of neck muscle activities were observed while performing a “Reading” task and holding mobile devices with hand. Lower levels of neck muscle activities were also observed when using a smart phone vs. a tablet, however such change was statistically insignificant.Relevance to industryThe current study demonstrated that users maintain deep neck flexion when using touchscreen mobile devices. In the recent years, there is an increasing popularity of mobile smart devices in various occupational environments. The findings of this study may be useful in implementing human-centered task designs to reduce neck injury risks among mobile device users.     

Information flow during crisis management: challenges to coordination in the emergency operations center

This paper discusses challenges to coordination in the emergency operations center (EOC). A county-level EOC is made up of representatives from a range of organizations including local government, fire, police, hospital, utility, and Red Cross representatives. These ad hoc teams are tasked with coming together during an emergency to obtain and deliver resources to first responders on the scene of the disaster, as well coordinating transportation of casualties, tracking of fatalities, and establishment of shelters. Two county-level exercises were observed. Themes were identified across the two exercises. Recommendations for better supporting coordination in crisis management are offered.     

Cervical spine biomechanics and task performance during touchscreen computer operations

The effects of different touchscreen interface designs on operators' task performance and cervical spine biomechanics were investigated in the current study. Fifteen male participants performed “Whac-a-Mole” type of visual target pinpointing tasks on a touchscreen monitor with different display sizes, icon sizes, icon colors and task difficulties. Participants' task performance, cervical spine biomechanics and upper extremity muscle activities were recorded and compared. Results demonstrated that an oversized desktop touchscreen monitor and small icons generated negative impacts on participants’ task performance and biomechanical measurements. Lighter icon color and more difficult task requirement generated worse task performance but had limited impact on cervical spine biomechanics. In addition, when using an oversized touchscreen monitor, the impacts of icon size and task difficulty seem to be magnified. Our results demonstrated that a more human-oriented interface design could help improve task performance and reduce neck and upper extremity injuries while operating touchscreen monitors.Relevance to industryIn this study we investigated how a number of different design factors could influence task performance as well as cervical spine biomechanics when using touchscreen monitors. Knowledge gained from the current study could help the design of future applications that involve finger touching operations on touchscreen monitors.     

Comparing stationary standing with an intermittent walking posture during assembly operations

The purpose of this investigation was to evaluate two different standing postures, intermittent walking (dynamic) and stationary, on 11 volunteers. While performing the activity in a stationary posture, volunteers worked barefoot for 25 minutes at a particular workstation, taking up to five passive breaks. The dynamic standing postural activity was similar in every respect with the exception of the nature of the breaks that were spent walking from one workstation to the other. Foot pressure was analyzed using a static evaluation variable (contact area) and a dynamic evaluation variable (area pressure change root mean square [aPcrms]). Foot center of pressure (COP) was analyzed using two of its features: excursion length (LEN) and root mean square velocity of excursions (VEL). In addition, a psychophysical study was used to distinguish the comfort levels of various muscles between the two postures. The quantifications of the four physiological variables revealed a lower comfort index (p < 0.05) in stationary standing compared to dynamic standing during assembling duties. This significant distinction was further corroborated by the results of the psychophysical test. Such a positive influence of the dynamic standing posture on standing comfort can be used to improve industrial productivity. © 2008 Wiley Periodicals, Inc.     

Institution-governed cross-domain agent service cooperation: a model for trusted and autonomic service cooperation

Constructing Virtual Organizations (VOs) by creating service cooperation (i.e. service-oriented cooperation) has become a mainstream approach for reforming the development of application software systems in Web environments. However, the inherent non-controllability of business services across different management domains has brought on the so-called ??trust?? crisis that the success and benefit of cooperation cannot be ensured. It is this crisis that cumbers the achievement of autonomic cooperation and thereby the large-scale deployment of VOs. Therefore, this paper proposes a model, called IGTASC, to conquer this crisis and make service cooperation both trusted and autonomic by developing three closely-coupled technologies: institution-governed cooperation, policy-driven self-management, and community facilitation management.     

Compelled operations and operations of degreeP

We definen-ary (n ≥ 1) operations compelled by an operator and operations of degreep, generalizations of Greibach's binary syntactic operations. We show that properties of binary syntactic operators remain right forn-ary operations (n ≥ 1) and further for idempotent operations. We obtain so hierarchy theorems among full semiAFLs and new properties about classical operations and classical families of languages. The new definitions and properties are illustrated by study of a family ofn-ary operations.     

D-WARD: a source-end defense against flooding denial-of-service attacks

Defenses against flooding distributed denial-of-service (DDoS) commonly respond to the attack by dropping the excess traffic, thus reducing the overload at the victim. The major challenge is the differentiation of the legitimate from the attack traffic, so that the dropping policies can be selectively applied. We propose D-WARD, a source-end DDoS defense system that achieves autonomous attack detection and surgically accurate response, thanks to its novel traffic profiling techniques, the adaptive response and the source-end deployment. Moderate traffic volumes seen near the sources, even during the attacks, enable extensive statistics gathering and profiling, facilitating high response selectiveness. D-WARD inflicts an extremely low collateral damage to the legitimate traffic, while quickly detecting and severely rate-limiting outgoing attacks. D-WARD has been extensively evaluated in a controlled testbed environment and in real network operation. Results of selected tests are presented in the paper.     

Fast flooding over Manhattan

We consider a Mobile Ad-hoc NETwork (MANET) formed by $n$ agents that move at speed $\text{ v}$ according to the Manhattan Random-Waypoint model over a square region of side length $L$ . This model has stationary properties that strongly depart from the well-studied Random-Walk model and that are typical in scenarios of vehicular traffic in urban zones. For instance, the resulting stationary (agent) spatial probability distribution is far to be uniform: the average density over the “central zone” is asymptotically higher than that over the “Suburb”. Agents exchange data if and only if they are at (Euclidean) distance at most $R$ within each other. We study the flooding time of this MANET: the number of time steps required to broadcast a message from one source agent to all agents of the network in the stationary phase. We prove the first asymptotical upper bound on the flooding time. This bound holds with high probability, it is a decreasing function of $R$ and $\text{ v}$ , and it is tight for a wide and relevant range of the network parameters (i.e. $L, R$ and $\text{ v}$ ). A consequence of our result is that flooding over the sparse and highly-disconnected Suburb can be as fast as flooding over the dense and connected central zone. This property holds even when $R$ is exponentially below the connectivity threshold of the MANET and the speed $\text{ v}$ is very low.     

Project scheduling under partially renewable resources and resource consumption during setup operations

There has been an increasing pressure on manufacturing industries to reduce energy consumption. In this study, we propose a new variant of RCPSP called RCPSP/πRC, which can deal with realistic energy constraints such as power restriction during peak hours, contract demand, and energy consumption during setup operations. First, we present an integer programming (IP) model and a constraint programming (CP) model of the RCPSP/πRC. Next, we present a heuristic mode restriction method called a mask calculation algorithm to achieve efficient searching by restricting selectable modes. Finally, through computational experiments, we evaluate the proposed methods and show their effectiveness.