Improving pedestrians’ navigation safety at night by enhancing legibility of foreground and background information on the display

Traffic intersections are dangerous areas for pedestrians at night, primarily when people use their mobile phones while walking; pedestrians’ line of sight switches between their phones and the environment, which causes inattentional blindness during emergencies. The salience of the foreground and background information is different by the lightness conditions; therefore, identifying the lightness level of the foreground and background is critical. In this study, the brightness of urban traffic intersection scenes in the nighttime was analyzed, and improved color tones of the navigation interface for enhancing information recognition were identified. Moreover, identify the balance of visual attention by adjusting lightness and color treatment between foreground and background information. A glance legibility experiment indicated that a warm color tone with contrast and gamma correction under a lighting value of 65 in the LAB color mode is the optimal recognition combination. The results of this study indicated that low gamma under high lighting effectively reduced glare-related distractions and resulted in the lowest error rate in background information recognition. This paper proposes increasing the visual attention of urban pedestrians during nighttime navigation through the balancing of the lighting of the foreground interface and the color treatment of the background. Navigating at nighttime can be safer when their attention toward the environment increases and decreases attention distraction.     

Does prolonged sitting with limited legroom affect the flexibility of a healthy subject and their perception of discomfort?

This study examined for differences in subjective ratings of discomfort and comfort (Numerical Rating Scale) and objective measures of hamstring (Sit-Reach test), lumbar (Schöber’s test) and neck (Cervical Range of Motion) flexibility in healthy young subjects (n = 24) following 4 h of sitting on stacking chairs with or without limited legroom.When comparing the limited and unlimited legroom groups for differences in subjective and objective measures over 4 h, no significant findings were seen at the 5% level of confidence. However, differences in buttock, neck, shoulder and average discomfort were significantly negatively correlated to differences between post-warm up Sit-Reach scores (Correlation Co-efficients: −.763, −.434, −.408, and −.445; p values of .004, .034, .048, and .029, respectively). The difference in buttock discomfort was significantly negatively correlated to the difference between pre-warm up Sit-Reach scores (Correlation Coefficient: −.750; p = 0.005), post-sitting/pre-warm up and pre-sitting/post-warm up Sit-Reach scores (Correlation Coefficient: −.756; p = 0.004), and Schöber’s tests (Correlation Coefficient: −.578; p = 0.049).Although the above results suggest a relationship between a loss in flexibility and an increase in discomfort, the mechanism influencing this relationship is not clear from this study. What does appear clear is that the limiting of legroom to the parameters used in this study does not seem to exacerbate change in flexibility and discomfort which are a consequence of prolonged sitting.

Relevance to industry

Many forms of public transport provide limited legroom for their passengers, which may have an adverse affect on the user’s flexibility or experience of discomfort. Determining which objectively measurable parameters are associated with the subjective level of discomfort during sitting should allow for a greater appreciation of the changes that underpin such subjective perceptions.     

Upper quadrant postural changes of school children in response to interaction with different information technologies

The objective of this study was to quantitatively analyse the sitting posture of school children interacting with both old (book) and new (laptop and desktop computers) information technologies to test the hypothesis that posture is effected by the type of information technology (IT) used. A mixed model design was used to test the effect of IT type (within subjects) and age and gender (between subjects). The sitting posture of 32 children aged 4?–?17 years was measured whilst they read from a book, laptop, and desktop computer at a standard school chair and desk. Video images were captured and then digitized to calculate mean angles for head tilt, neck flexion, trunk flexion, and gaze angle. Posture was found to be influenced by IT type (p?<?0.001), age (p?<?0.001) and gender (p?=?0.024) and significantly correlated to the stature of the participants. Measurement of resting posture and the maximal range of motion of the upper and lower cervical spines in the sagittal plane was also undertaken. The biophysical impact and the suitability of the three different information technologies are discussed.     

Discomfort of seated persons exposed to low frequency lateral and roll oscillation: Effect of seat cushion

The discomfort caused by lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation has been investigated at frequencies between 0.25 and 1.0 Hz when sitting on a rigid seat and when sitting on a compliant cushion, both without a backrest. Judgements of vibration discomfort and the transmission of lateral and roll oscillation through the seat cushion were obtained with 20 subjects. Relative to the rigid seat, the cushion increased lateral acceleration and roll oscillation at the lower frequencies and also increased discomfort during lateral oscillation (at frequencies less than 0.63 Hz), roll oscillation (at frequencies less than 0.4 Hz), and fully roll-compensated lateral oscillation (at frequencies between 0.315 and 0.5 Hz). The root-sums-of-squares of the frequency-weighted lateral and roll acceleration at the seat surface predicted the greater vibration discomfort when sitting on the cushion. The frequency-dependence of the predicted discomfort may be improved by adjusting the frequency weighting for roll acceleration at frequencies between 0.25 and 1.0 Hz.     

Vicarious perception of postural discomfort and exertion

Perceived exertion and discomfort have been used extensively in ergonomics practice. Job incumbents typically rate their exertion on scales such as Borg's rated perceived effort (RPE) and their discomfort on scales such as Corlett and Bishop's body part discomfort scales (BPD). This study asks whether exertion and discomfort can be perceived by an external observer, i.e. is vicarious perception possible? Four participants (targets) performed 20 postural holding tasks selected from Ovako Working Posture Analysing System postures and gave RPE and BPD scores for each posture. Video clips of each target in each posture were shown to four expert ergonomists and 23 novices, who also gave RPE and BPD scores. Correlations between targets and observers scores were high, with significance exceeding p = 0.01. Observers were generally conservative, rating easy postures too high and difficult postures too low. All observers rated female targets higher than male targets. Female observers rated all targets higher then male observers. Vicarious perception of discomfort and exertion was possible, but there was not a one-to-one correspondence to ratings given by those experiencing the posture.     

Sitting comfort and discomfort and the relationships with objective measures

The concepts of comfort and discomfort in sitting are under debate. There is no widely accepted definition, although it is beyond dispute that comfort and discomfort are feelings or emotions that are subjective in nature. Yet, beside several subjective methodologies, several objective methods (e.g. posture analysis, pressure measurements, electromyography (EMG) are in use to assess sitting comfort or discomfort. In the current paper a theoretical framework is presented, in which comfort and discomfort were defined and the hypothetical associations with underlying factors were indicated. Next, the literature was reviewed to determine the relationships between objective measures and subjective ratings of comfort and discomfort. Twenty-one studies were found in which simultaneous measures of an objective parameter and a subjective rating of comfort or discomfort were obtained. Pressure distribution appears to be the objective measure with the most clear association with the subjective ratings. For other variables, regarding spinal profile or muscle activity for instance, the reported associations are less clear and usually not statistically significant.     

Evaluation of a prototype multi-posture office chair

Office chairs have often been designed to promote a single ‘correct’ rather rigid and upright posture, yet it is acknowledged that allowing changes in posture is good ergonomics practice. The present study investigated office worker's preferences for a standard shaped typist's chair (ST) and a prototype multi-posture (PMP) office chair designed to allow its users a variety of sitting positions. Forty-two (22 male and 20 female) telesales personnel (12), clerical staff (12) and researchers (18) used ST or PMP in their workplace for the first week of a 2-week study (with an even number in each work area). The PMP chair was introduced to participants with a brief lecture on how to use it and with an information booklet. Following this, each participant completed a chair comfort questionnaire. In the second week, participants swapped chairs and again completed the chair comfort questionnaire. At the end of the second week participants were also asked to complete a separate questionnaire about the usability of the information booklet that accompanied the PMP chair. Statistically significant differences in subject's rating of the two chairs were observed in 7 out of 19 questions. On a 100 mm scale, the ST chair was rated as having a greater mean overall acceptability, desirability and suitability for body build than the PMP chair. Participants also claimed to achieve better posture in the ST chair, that they tipped forward less and were more satisfied with its width. Although the participants generally preferred the ST chair, the PMP chair received more favourable ratings among the researchers who were quite mobile in their work, and in whom there was a trend for less neck, shoulder and upper back discomfort. More participants reported an overall preference for the PMP chair. The findings suggest that a more aesthetically acceptable PMP chair should be developed, peoples' reasons for preferring a more traditionally designed chair should be explored, and that the effect of postural stability education on personal preconceptions should be examined to obtain an optimal combination of healthy sitting habits, comfort and aesthetic qualities in an office chair.     

Analysis of Frequency,Intensity, and Interference of Discomfort in Computerized Numeric Control Machine Operations

The introduction of Computerized Numeric Control (CNC) technology in manufacturing industries revolutionized the production process a few decades back. There are some health and safety problems associated with these machine operations, however. The main objectives of the present work is to study the health and safety issues associated with the CNC machines with respect to control and display, specifically to determine the frequency, intensity of discomfort, and its interference in operating different CNC machines as reported by the workers operating them. The postural discomfort associated with CNC machines was studied, and the frequency, intensity of discomfort, and interference of the level of discomfort with the participants' ability to work were recorded and analyzed. The study revealed that 20.5% of the operators reported discomfort 1 or 2 times, 25.4% experienced discomfort 3 to 4 times in a week, 37.7% had discomfort daily, and 16.4% reported discomfort several times a day. Discomfort was reported in all the body parts involved (lower back, neck, upper back, shoulder, and leg), but the highest discomfort scores were associated with the shoulder and arm region. Workers reporting discomfort several times a day also reported high mean discomfort scores. The study established that the frequency and intensity of the discomfort in all body parts is related to the position of the control panel and display. © 2012 Wiley Periodicals, Inc.     

The influence of lift frequency,lift duration and work experience on discomfort reporting

Discomfort surveys are commonly used to assess risk in the workplace and prioritize jobs for interventions before an injury or illness occurs. However, discomfort is a subjective measure and the relationship of discomfort to work-related factors is poorly understood. The objective of this study was to understand how reports of discomfort relate to work-related risk factors for the low back. A total of 12 novice and 12 experienced manual materials handlers performed repetitive, asymmetric lifts at different load levels and at six different lift frequencies throughout an 8-h exposure period. Discomfort was recorded hourly throughout the day. Analyses were performed to determine which experimental factors influenced reporting of discomfort and if discomfort trends matched spine loading trends. Novice lifters reported significantly higher discomfort levels than experienced subjects. They also reported increases in discomfort as moment exposure increased and as the exposure time increased. Novices lifting at 8 Nm load moment level reported increased discomfort from 0.07 to 0.63 by the end of the day, at 36 Nm they reported an increase from 0.04 to 0.40 and at 85 Nm they reported an increase from 0.37 to 3.06. Experienced subjects, on the other hand, reported low levels of discomfort regardless of moment exposure, lift frequency or exposure duration. The reported discomforts were generally unrelated to the biomechanical loading on the spine. Discomfort reporting appears to be more a reflection of experience than of work risk factor exposure. Experienced subjects may have more efficient motor patterns, which reduce spinal load and thus discomfort. Novice subjects seemed to have a lower threshold of discomfort. Caution is needed when using discomfort reporting as a means to identify jobs in need of interventions, in that biomechanical loading may not be accurately represented. Discomfort should only be used as a supplement to objective measures, such as spinal loading, to assess the risk of low back disorders.     

A method for analytically generating three-dimensional isocomfort workspace based on perceived discomfort

The purpose of this study was to develop a new method for analytically generating three-dimensional isocomfort workspace for the upper extremities using the robot kinematics. Subjective perceived discomfort scores in varying postures for manipulating four types of controls were used. Fifteen healthy male subjects participated in the experiment. The subjects were asked to hold the given postures manipulating controls for 60 s in the seated position, and to rate their perceived discomfort during the following rest of 60 s using the magnitude estimation. Postures of the upper extremities set by shoulder and elbow motions, types of controls, and left right hand were selected as experimental variables, in which the L32 orthogonal array was adopted. The results showed that shoulder flexion and adduction-abduction, elbow flexion, and types of controls significantly affected perceived discomfort for postures operating controls, but hand used for operating controls did not. Depending upon the types of controls, four regression models predicting perceived discomfort were presented. Using the models, a sweeping algorithm to generate three-dimensional isocomfort workspace was developed, in which the robot kinematics was employed to describe the translational relationships between the upper arm and the lower arm/hand. It is expected that the isocomfort workspace can be used as a valuable design guideline when ergonomically designing three-dimensional workplaces.