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Giulia Patelli, Miyuki Morioka, Michael J Griffin
The frequency content of a mechanical shock is not confined to its fundamental frequency, so it was hypothesized that the frequency-dependence of discomfort caused by shocks with defined fundamental frequencies will differ from the frequency-dependence of sinusoidal vibration. Subjects experienced vertical vibration and vertical shocks with fundamental frequencies from 0.5 to 16 Hz and magnitudes from ±0.7 to ±9.5 ms-2. The rate of growth of discomfort with increasing magnitude of motion decreased with increasing frequency of both motions, so the frequency-dependence of discomfort varied with the magnitudes of both motions and no single frequency weighting will be ideal for all magnitudes...
January 17, 2018: Ergonomics
Shabboo Valipoor, Debajyoti Pati, Matt S Stock, Doug Bazuin
A vast majority of patient fall events in hospitals involve the elderly. In inpatient care settings, despite the risk of fall, patients are encouraged to leave their bed, move around their room, and sit on their chair to progress in their healing. Despite the vital role of patient chair design in improving recovery, few studies have examined the ergonomic requirements of safe patient chairs. This study examined the impact of manipulating horizontal and vertical positions of armrests in a test chair on required physical effort during Stand-to-Sit-to-Stand (St-Si-St) transitions among fifteen elderly women...
January 11, 2018: Ergonomics
Andreas Gregoriades, Alistair Sutcliffe
Situation awareness (SA) constitutes a critical factor in road safety, strongly related to accidents. This paper describes the evaluation of a proposed SA enhancement system (SAES) that exploits augmented reality through a head-up display. Two SAES designs were evaluation (information rich v. minimal information) using a custom-made simulator and the Situation Awareness Global Assessment Technique (SAGAT) with performance and EEG measures. The paper describes the process of assessing the SA of drivers using the SAES, through a series of experiments with participants in a Cave Automatic Virtual Environment (CAVE)...
January 11, 2018: Ergonomics
Yue Wei, Jiayue Zheng, Richard H Y So
Visually induced motion sickness (VIMS) is a common discomfort response associated with vection-provoking stimuli. It is suggested that VIMS susceptibility depends on the ability to regulate visual performance during vection. To test this, in total 29 participants, with VIMS susceptibility assessed by Motion Sickness Susceptibility Questionnaire, were recruited in three successive experiments to perform sustained attention to response tests (SARTs) while watching dot pattern stimuli known to provoke roll-vection...
January 11, 2018: Ergonomics
Linda M Rose, Catherine A A Beauchemin, W Patrick Neumann
This study's objective was to develop models of endurance time (ET), as a function of load level (LL), and of resumption time (RT) after loading as a function of both LL and loading time (LT) for repeated loadings. Ten male participants with experience in construction work each performed fifteen different one-handed repetaed pushing tasks at shoulder height with varied exerted force and duration. This data was used to create regression models predicting ET and RT. It is concluded that power law relationships are most appropriate to use when modelling ET and RT...
January 11, 2018: Ergonomics
Timo Melman, David A Abbink, Marinus M van Paassen, Erwin R Boer, Joost C F de Winter
We conceptually replicated three highly cited experiments on speed adaptation, by measuring drivers' experienced risk (galvanic skin response; GSR), experienced task difficulty (self-reported task effort; SRTE), and safety margins (time-to-line-crossing; TLC) in a single experiment. The three measures were compared using a nonparametric index that captures the criteria of constancy during self-paced driving and sensitivity during forced-paced driving. In a driving simulator, 24 participants completed two forced-paced and one self-paced run...
January 10, 2018: Ergonomics
Henry T Peng, Fethi Bouak, Wenbi Wang, Renee Chow, Oshin Vartanian
Fatigue has become an increasing problem in our modern society. Using MATLAB as a generic modelling tool, a fatigue model was developed based on an existing one and compared with a commercial fatigue software for prediction of cognitive performance under total and partial sleep deprivation. The flexibility of our fatigue model allowed additions of new algorithms and mechanisms for non-sleep factors and countermeasures and thus improved model predictions and usability for both civilian and military applications...
January 8, 2018: Ergonomics
Yuxin Wu, Hong Liu, Baizhan Li, Yong Cheng, Daniel Mmereki, Deyu Kong
In practice, passengers actively respond to the thermal environment when they board an aircraft in winter, which is not considered in the current standards. In this study, the behavioural, physiological, and psychological responses to the thermal environment were examined at 22 °C (with 68 subjects), 20 °C, and 26 °C (with 32 subjects). The results showed that the three air temperature levels had significant effect on nozzle usage and clothing adjustment behaviours, surface skin temperature, and thermal sensation vote (TSV)...
December 29, 2017: Ergonomics
Graham K Edgar, Di Catherwood, Steven Baker, Geoff Sallis, Michael Bertels, Helen E Edgar, Dritan Nikolla, Susanna Buckle, Charlotte Goodwin, Allana Whelan
This paper presents a model of situation awareness (SA) that emphasises that SA is necessarily built using a subset of available information. A technique (Quantitative Analysis of Situation Awareness - QASA), based around signal detection theory, has been developed from this model that provides separate measures of actual SA (ASA) and perceived SA (PSA), together with a feature unique to QASA, a measure of bias (information acceptance). These measures allow the exploration of the relationship between actual SA, perceived SA and information acceptance...
December 29, 2017: Ergonomics
Chuan Sun, Bryan Buchholz, Margaret Quinn, Laura Punnett, Catherine Galligan, Rebecca Gore
Home care aides risk musculoskeletal injury because they lift and move clients; the body weight of most adults exceeds the NIOSH recommended limit for lifting (Waters 2007). Methods to reduce manual patient lifting in institutional settings are often technically or economically infeasible in home care. Our goal was to identify suitable, safe, low-technology transfer devices for home care use. Sixteen experienced home care aides performed client transfers from wheelchair to bed (upward) and bed to wheelchair (downward) in a simulated home care environment (laboratory), using four different slide boards and by hand without a device...
December 21, 2017: Ergonomics
Eric B Weston, Alexander Aurand, Jonathan S Dufour, Gregory G Knapik, William S Marras
Though biomechanically-determined guidelines exist for lifting, existing recommendations for pushing and pulling were developed using a psychophysical approach. The current study aimed to establish objective hand force limits based on the results of a biomechanical assessment of the forces on the lumbar spine during occupational pushing and pulling activities. Sixty-two subjects performed pushing and pulling tasks in a laboratory setting. An electromyography-assisted biomechanical model estimated spinal loads, while hand force and turning torque were measured via hand transducers...
December 15, 2017: Ergonomics
Nataly Zion, Anat Drach-Zahavy, Tamar Shochat
Sleepiness is a common complaint during the night shift and may impair performance. The current study aimed to identify bio-psycho-social factors associated with subjective sleepiness during the night shift. Ninety-two female nurses working rotating shifts completed a sociodemographic questionnaire, the Munich ChronoType Questionaire for shift workers, the Pittsburg Sleep Quality Index and the Pre-sleep Arousal Scale. Subjective sleepiness was measured hourly during two night shifts using the Karolinska Sleepiness Scale, and activity monitors assessed sleep duration 24-hours before each shift...
December 14, 2017: Ergonomics
Bernhard Schwartz, Jay M Kapellusch, Andreas Schrempf, Kathrin Probst, Michael Haller, Arnold Baca
Prolonged sitting is a risk factor for several diseases and the prevalence of worksite-based interventions such as sit-to-stand workstations is increasing. Although their impact on sedentary behaviour has been regularly investigated, the effect of working in alternating body postures on cognitive performance is unclear. To address this uncertainty, forty-five students participated in a two-arm, randomized controlled cross-over trial under laboratory conditions. Subjects executed validated cognitive tests (working speed, reaction time, concentration performance) either in sitting or alternating working postures on two separate days (ClinicalTrials...
December 13, 2017: Ergonomics
Leigh J Allin, Maury A Nussbaum, Michael L Madigan
This study investigated the relationship between feet kinematics upon slipping while walking and the outcome of the slip. Seventy-one slips (induced by walking over an unexpectedly slippery surface) were analysed, which included 37 recoveries, 16 feet-split falls, 11 feet-forward falls, and seven lateral falls. Feet kinematics differed between these four slip outcomes, and a discriminant model including six measures of feet kinematics correctly predicted 87% of slip outcomes. Two potentially modifiable characteristics of the feet kinematics upon slipping that can improve the likelihood of successfully averting a fall were identified: (1) quickly arresting the motion of the slipping foot; and (2) a recovery step that places the trailing toe approximately 0-10% body height anterior to the sacrum...
December 12, 2017: Ergonomics
Bin Liu, Liang Ma, Chi Chen, Zhanwu Zhang
This study aimed at experimentally validating a subject-specific maximum endurance time (MET) model. Thirty health participants (15 males and 15 females; Age: mean = 21.5 years, SD = 1.6 years) volunteered to conduct an isometric elbow flexion task until exhaustion. The endurance times of each participant were measured under relative exertion levels ranging from 30%MVC (Maximum Voluntary Contraction) to 70%MVC at 10% intervals. Assessment of the model showed that the intensity-endurance time relationship for each studied individual could be well fitted by the subject-specific MET model (R2 > 0...
December 9, 2017: Ergonomics
Neville A Stanton, Katherine L Plant, Aaron P Roberts, Craig K Allison
Flight within degraded visual conditions is a great challenge to pilots of rotary-wing craft. Environmental cues typically used to guide interpretation of speed, location and approach can become obscured, forcing the pilots to rely on data available from in-cockpit instrumentation. To ease the task of flight during degraded visual conditions, pilots require easy access to flight critical information. The current study examined the effect of "Highways in the Sky" symbology and a conformal virtual pad for landing presented using a Head Up Display (HUD) on pilots' workload and situation awareness for both clear and degraded conditions across a series of simulated rotary-wing approach and landings...
December 5, 2017: Ergonomics
Fábio Barbosa Rodrigues, Rina Márcia Magnani, Georgia Cristina Lehnen, Gustavo Souto de Sá E Souza, Adriano O Andrade, Marcus Fraga Vieira
Overloaded backpacks can cause changes in posture and gait dynamic balance. Therefore, the aim of this study was to assess gait regularity and local dynamic stability in young adults as they carried a backpack in different positions, and with different loads. Twenty-one healthy young adults participated in the study, carrying a backpack that was loaded with 10% and 20% of their body weight (BW). The participants walked on a level treadmill at their preferred walking speeds for 4 min under different conditions of backpack load and position (i...
December 5, 2017: Ergonomics
Shuchi Agarwal, Craig Steinmaus, Carisa Harris-Adamson
BACKGROUND: Sit-stand workstations are proposed solutions to reduce sedentary time at work. Numerous companies are using them to mitigate health concerns such as musculoskeletal discomfort. OBJECTIVE: To review the literature on sit-stand workstations and low back discomfort. METHOD: We conducted a meta-analysis on literature published before 17 November 2016 that addressed the relationship between sit-stand workstations and musculoskeletal discomfort, focusing on the low back...
December 4, 2017: Ergonomics
Liana Michele Tennant, Helen Christina Chong, Stacey Marie Acker
Occupational kneeling is associated with an increased risk for tibiofemoral knee osteoarthritis. Forces on the knee in the kneeling posture, as well as the greater incidence of meniscus tears among workers likely contribute to the increased risk. We hypothesize that an additional mechanism may contribute - altered neuromuscular control due to prolonged high knee flexion. Forty participants (20 male, 20 female) completed an evaluation of gait and squatting before, immediately following, and 30 minutes following a 30-minute simulated occupational kneeling exposure...
December 1, 2017: Ergonomics
Mikkel Brandt, Pascal Madeleine, Afshin Samani, Markus Due Jakobsen, Sebastian Skals, Jonas Vinstrup, Lars Louis Andersen
The aim was to classify lifting activities into low and high risk categories (according to The Danish Working Environment Authority guidelines) based on surface electromyography (sEMG) and trunk inclination (tri-axial accelerometer) measurements. Lifting tasks with different weights, horizontal distance and technique were performed. The lifting tasks were characterized by a feature vector composed of either the 90(th), 95(th) or 99(th) percentile of sEMG activity level and trunk inclinations during the task...
November 24, 2017: Ergonomics
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