Assessment of passenger long-term vibration discomfort: a field study in high-speed train environments

Discomfort estimation for vertical whole-body vibration in the aircraft cabin considering the duration and static sitting comfort

This paper investigated the discomfort caused by vertical whole-body vibration (WBV) over 20 minutes using data recorded at the front, middle, and rear seats of the passenger cabin in civil aviation during a cruising flight. Twenty-four subjects experienced each stimulus at 0.5 ms-2 r.m.s. and judged discomfort at various moments (i.e. 1/6, 5, 10, 15, and 20 min) using a category-ratio method. The difference in discomfort due to high-frequency vibration components vanished after 10 min. Based on Stevens' power law, a method is developed to estimate long-term vertical WBV discomfort by considering the static discomfort and an interaction coefficient between vibration and static discomfort as parameters. The proposed estimation method showed high accuracy with determination coefficients (R2) higher than 0.97 and good linearity with values of growth rates 0.95, 1, and 0.95 for the vertical WBV discomfort at the front, middle, and rear seat positions in the aircraft cabin.Practitioner summary: An estimation method for the discomfort caused by vertical WBV considering the duration and static sitting discomfort is developed. This method can provide accurate discomfort estimating for long-term vibration exposure, e.g. in civil aviation during a cruising flight, by introducing an 'interaction term' between static and dynamic discomfort.

Evaluation and prediction method of railway passenger long-term vibration comfort under complex operating conditions

Vibration contributes large increases in railway passenger discomfort during long-term sitting. Discomfort caused by vibration may differ in different operation conditions. This paper conducted field measurements to investigate the interrelationships between the three. Participants completed a 240-min train journey with their whole-body vibration, subjective comfort ratings and train operating parameters being recorded. A large correlation was observed between the estimated vibration dose value and subjective comfort. The relationship that vibration magnitude significantly increases with increasing the train speed and tunnel density was also found and quantified. A vibration exposure limit of 2.08 m/s1.75 corresponding to the boundary between subjective ratings of comfortable and discomfortable was obtained. Based on the exposure limit and the quantified relationship, a vibration comfort prediction method that can calculate the passenger's maximum tolerance time under a given operation condition was proposed and may help in determining the optimal operating speed and tunnels distribution to alleviate vibration discomfort. Practitioner summary: Similar to the guide to effect of vibration on health in current standard, a vibration exposure limit regarding comfort was provided for reference when assessing long-term vibration comfort. Meanwhile, a prediction method was proposed for determining the best train operating speed and tunnels distribution, thereby alleviating railway passengers' vibration discomfort.

Ergonomic and Anthropometric Evaluation of Locally Manufactured Vehicle Seats

Background

Most of the cars are imported as cargo vehicles and then converted into commercial passenger vehicles in Ethiopia. Seats are locally manufactured and installed as part of the conversion to passenger cars, with little regard permitted for the standard specifications required.

Objective

A descriptive survey, an ergonomics assessment of passenger seats was conducted, and subjective evaluations of seat comfort were collected.

Methods and Materials

For long journeys, there are problems of discomfort, back pain, and human fatigue. Anthropometric measurements of respondents and locally manufactured seats were used to conduct an objective evaluation of seat attributes.

Results

The findings revealed that the passengers' body proportions and the seat dimensions differ significantly and are not given any preference during design and fabrication of the seat.

Conclusion

This study recommends the anthropometric dimensions of the Ethiopian passengers for the design and manufacturing of the vehicle seats.

Influences of cushion contour on passenger comfort and interface pressure in high-speed train

In this paper, eight different contoured cushions (S1-S8) in two categories (flat and wrapped) were designed to study the influence of different contoured cushions on passenger comfort in high-speed trains. Meanwhile, subjective data investigation by the comfort Likert Scale questionnaire and objective physical variables collection by the body-cushion contact pressure test was carried out. In addition, one-way ANOVA and Pearson correlation analysis were performed on the subjective survey and objective test data. The results show that the cushion contours had a significant effect on the subjective evaluation of the overall comfort of the participants, in which the overall comfort below the waist of the separated wrapped cushion S8 has the highest subjective comfort score. The overall comfort of the flat-front bulge type cushion S4 and the local comfort of the thighs and the root of the thighs were rated higher than other flat types. Under the flat cushion, the effect of stature characteristics (mainly weight and hip-width) on the overall comfort subjective ratings was insignificant, and the effect on the contact pressure distribution variables was significant, but the contact pressure distribution variables were not correlated with the comfort ratings. Under the wrapped cushion, the effect of stature characteristics on the overall comfort subjective ratings and contact pressure distribution variables was significant. There were positive and negative correlations between the average peak contact pressure and average contact pressure and comfort ratings, respectively.

Influencing factors and mechanism of high-speed railway passenger overall comfort: Insights from source functional brain network and subjective report

Overall comfort is the priority for the high-speed railway (HSR) passengers, while its influencing factors and mechanism are not yet apparent. According to the source functional brain network and subjective report, this study revealed the potential influencing factors and mechanisms of passengers overall comfort in high-speed railway environments. Here, an ergonomics field test with 20 subjects was conducted where subjective reports and electroencephalography (EEG) were collected. The electric-source imaging and functional connectivity were used to build the source functional brain network from EEG and network indices were extracted. Statistics analysis results showed that static comfort played the most critical role in the overall comfort, followed by emotional valence, emotional arousal, aural pressure comfort, vibration comfort, and noise comfort. Thermal and visual comfort were insignificant due to the well-designed heating, ventilation, and air conditioning (HVAC) and lighting system of HSR. In addition, the source functional brain network of passengers who felt uncomfortable had the higher clustering coefficient, assortativity coefficient and global efficiency, which meant greater activation of brain compared with passengers who were in a state of comfort. According to the local attributes indices analysis, most key brain regions were located in the frontal and hippocampus, which revealed emotion and spatial perception contribute to the whole comfort degradation process. This work proposed novel insights into HSR passengers overall comfort according to subjective and objective methods. Our findings demonstrate emotional regulation and seat improvements are key factors for future improvement of HSR passengers overall comfort.

Analysis of Train Car-Body Comfort Zonal Distribution by Random Vibration Method

With the increase in train speeds on high-speed railways, the excitation frequency of track irregularities increases, which has a negative impact on train comfort and opposes the passengers’ desire for high ride comfort. In addition, the uncertainty of train comfort results from the stationary randomness of track irregularities and the different zonal distribution in the car body. Therefore, the application of the stationary random vibration method to analyze the zonal distribution of train comfort and the relevant influencing factors is important to guarantee the passengers’ comfortable experience in each ride and to provide a theoretical basis for comfort optimization. First, the train was modeled using eight independent vehicle elements. Second, the pseudo-excitation method was applied to obtain the theoretical zonal distribution of the Sperling index, an indicator of comfort, via the linearity of the power spectrum density of train acceleration. Third, considering various factors affecting train comfort, the results were compared with those calculated using the Monte Carlo method. It was found that the most comfortable area was located slightly in the front of the center of the car body. Improving track irregularities and reasonably controlling the speed of a train will increase the train’s comfort, while it will deteriorate with a loss in car-body mass and damage to the secondary suspension system.

The Application of Electroencephalogram in Driving Safety: Current Status and Future Prospects

The driver is one of the most important factors in the safety of the transportation system. The driver's perceptual characteristics are closely related to driving behavior, while electroencephalogram (EEG) as the gold standard for evaluating human perception is non-deceptive. It is essential to study driving characteristics by analyzing the driver's brain activity pattern, effectively acquiring driver perceptual characteristics, creating a direct connection between the driver's brain and external devices, and realizing information interchange. This paper first introduces the theories related to EEG, then reviews the applications of EEG in scenarios such as fatigue driving, distracted driving, and emotional driving. The limitations of existing research have been identified and the prospect of EEG application in future brain-computer interface automotive assisted driving systems have been proposed. This review provides guidance for researchers to use EEG to improve driving safety. It also offers valuable suggestions for future research.