Seat Position Research Articles

The Effect of Seat Back Inclination on Spinal Alignment in Automotive Seating Postures.

Experimental studies have demonstrated a relationship between spinal injury severity and vertebral kinematics, influenced by the initial spinal alignment of automotive occupants. Spinal alignment has been considered one of the possible causes of gender differences in the risk of sustaining spinal injuries. To predict vertebral kinematics and investigate spinal injury mechanisms, including gender-related mechanisms, under different seat back inclinations, it is needed to investigate the effect of the seat back inclination on initial spinal alignment in automotive seating postures for both men and women. The purpose of this study was to investigate the effect of the seat back inclination on spinal alignments, comparing spinal alignments of automotive seating postures in the 20° and 25° seat back angle and standing and supine postures. The spinal columns of 11 female and 12 male volunteers in automotive seating, standing, and supine postures were scanned in an upright open magnetic resonance imaging system. Patterns of their spinal alignments were analyzed using Multidimensional Scaling presented in a distribution map. Spinal segmental angles (cervical curvature, T1 slope, total thoracic kyphosis, upper thoracic kyphosis, lower thoracic kyphosis, lumbar lordosis, and sacral slope) were also measured using the imaging data. In the maximum individual variances in spinal alignment, a relationship between the cervical and thoracic spinal alignment was found in multidimensional scaling analyses. Subjects with a more lordotic cervical spine had a pronounced kyphotic thoracic spine, whereas subjects with a straighter to kyphotic cervical spine had a less kyphotic thoracic spine. When categorizing spinal alignments into two groups based on the spinal segmental angle of cervical curvature, spinal alignments with a lordotic cervical spine showed significantly greater absolute average values of T1 slope, total thoracic kyphosis, and lower thoracic kyphosis for both the 20° and 25° seat back angles. For automotive seating postures, the gender difference in spinal alignment was almost straight cervical and less-kyphotic thoracic spine for the female subjects and lordotic cervical and more pronounced kyphotic thoracic spine for the male subjects. The most prominent influence of seatback inclination appeared in Total thoracic kyphosis, with increased angles for 25° seat back, 8.0° greater in spinal alignments with a lordotic cervical spine, 3.2° greater in spinal alignments with a kyphotic cervical spine. The difference in total thoracic kyphosis between the two seatback angles and between the seating posture with the 20° seat back angle and the standing posture was greater for spinal alignments with a lordotic cervical spine than for spinal alignments with a kyphotic cervical spine. The female subjects in this study had a tendency toward the kyphotic cervical spine. Some of the differences between average gender-specific spinal alignments may be explained by the findings observed in the differences between spinal alignments with a lordotic and kyphotic cervical spine.

Excavator driver seat occupational comfort assessment with Lumbar Support Cushion

The operators of excavators often suffer from dreadful Whole-Body Vibration. Besides, the operators are subject to postural instability which is considered to be a serious occupational health hazard. The main objective of this study is to investigate the role of Lumbar Support Cushion in mitigation of Whole-Body Vibration and postural instability under three different operating conditions such as Front-Manipulator Motion, Swing Motion and Propel-Drive Motion. The obtained Vibration Dose Value reveals a significant difference between the operation cycle (p < 0.001). Moreover, across the operation cycle with Lumbar Support Cushion a significant decrease in Vibration Dose Value (8) is observed on the operator seat-pan and backrest (p < 0.05). Further, the effect of Whole-Body Vibration on physiological stress factors, a significant decrease in systolic blood pressure by 1.26%, pulse rate by 2.75% and Rate Pressure Product by 4%, is observed with the use of Lumbar Support Cushion (p < 0.05) during the operation. The Lumbar Support Cushion helps in promoting a symmetric seating posture, and using Lumbar Support Cushion could help the excavator operator to increase in productivity during shift hour.

Change in seating position of children in towaway crashes from 1989 to 2019

ObjectiveThe purpose of this study was to examine the impact of the nationwide response to passenger airbag (PA) related deaths of children. The response was implemented in 1996 and focused on moving children to rear seats. This study determined the change in seating position of children from 1989 to 2019. MethodsField accident data on exposed occupants in towaway crashes was determined using 1989–2015 NASS-CDS in five groups (1989–1995, 1996–99, 2000–04, 2005–09 and 2010–15) and 2017–19 CISS in one group. Children were grouped as 0–2 yo (years old), 3–7 yo and 8–12 yo. Occupants 13 + were included for completeness. Seat position was defined as left-front (LF), right-front (RF), 2nd row and 3rd row. The weighted data provided an estimate for the change in seating position over time by occupant age with standard errors. ResultsFor 0–2 yo, 27.9% were in the RF seat in 1989–95. The fraction decreased to 0.40% in the 2017–19 (p < 0.001). For 3–7 yo, 32.1% were in the RF seat in 1989–95 and 3.2% in 2017–19 (p < 0.001). There has been a steady decrease in 0–7 yo using the RF seat. For 8–12 yo, there was a step decline in use of the RF seat from 39.5% in 1989–95 to 23.2% in the 2017–19 (p < 0.001). ConclusionsThe immediate reduction in front-seat use among younger children was associated with the nationwide public information efforts implemented in 1996 to move children to rear seats. Children up to 7 yo are no longer riding in the RF seat of vehicles in towaway crashes, unless there is no other option. Children 8–12 yo are still using the RF seat, but at a lower rate. The change in use of the RF seat for children 0–7 yo provides evidence that safety campaigns on placing young children in rear seats were successful in the US.

Hygro-thermo-mechanical performance of wheelchair cushion technologies in the prevention of pressure ulcers and moisture-associated skin damages

ABSTRACT This study aims at investigating the effects of three different wheelchair cushion technologies at the patient–wheelchair interface. To this end, eight participants were recruited to remain in an unrelieved seated position on a wheelchair successively equipped with three different cushions (foam, air-cell-based and gel), for a duration of 45 min. Interface pressure, temperature (measured with infrared thermography) and relative humidity were measured at the seat interface, at different timestamps. Experimental results show that foam cushion is significantly more efficient in reducing contact peak pressure (p < .01), while the gel cushion displays higher heat evacuation capabilities. In terms of relative humidity, no significant difference is observed among the three technologies (p > .29): all of them evacuate around only 10% of the total humidity compared to the reference situation (i.e., without cushion). Besides, a complementary numerical simulation corresponding to the steady state of the patient-wheelchair structure clearly highlights the temperature volume field at the underside of the seat, which acts like a thermal barrier and contributes to heat accumulation. Besides, an air flow at the underside of the chair in motion is shown to significantly reduce heat accumulation.

Analysis of individual differences in pelvic and spine alignment in seated posture and impact on the seatbelt kinematics using human body model.

Analysis using human body models has been performed to reduce the impact of accidents; however, no analysis has shown a relationship between lumbar and pelvic/spine angle and seat belts in reducing human damage from accidents. Lumbar and pelvic/spine angles were measured in 75 individuals and the measurements were used to create three different angles for the Total Human Model for Safety model. In the present study, we focused on lumber lordosis (LL) and pelvic angle (PA). A normal distribution and histogram were used for analysis of PA (01, 10, and 50). The Total Human Model for Safety, including LL and PA, was corrected using finite element software. Simulations were conducted under the conditions of the Japan New Car Assessment Programme (JNCAP) 56 kph full lap frontal impact. Using the results of the FEM, the amount of lap-belt cranial sliding-up, anterior movement of the pelvis, posterior tilt of the pelvis, head injury criterion (HIC), second cervical vertebrae (C2) compressive load, C2 moment, chest deflectiou (upper, middle, and lower), left and right femur load, and shoulder belt force were measured. The lap-belt cranial sliding-up was 1.91 and 2.37 for PA10 and PA01, respectively, compared to PA50; the anterior movement of the pelvis was 1.08 and 1.12 for PA10 and PA01, respectively; and the posterior tilt of the pelvis was 1.1 and 1.18 for PA10 and PA01, respectively. HIC was 1.13 for PA10 and 1.58 for PA01; there was no difference in C2 compressive load by PA, but C2 moment increased to 1.59 for PA10 and 2.72 for PA01. It was found that as LL increases and the PA decreases, the seat belt becomes likely to catch the iliac bone, making it harder to cause injury. This study could help to reconsider the safe seat and seatbelt position in the future.

Frequency of Musculoskeletal Pain Among Biomedical Science Students Working in Laboratory

Objective: To find out the frequency of musculoskeletal pain and to identify risk factors among biomedical science students working in laboratory Methods: This cross-sectional study used Nordic musculoskeletal questionnaire among biomedical science students and was conducted in the university of Central Punjab and University of Lahore, Pakistan. Study sample comprised of 103 participants. Data was collected by using non-probability convenient sampling technique and was analyzed through SPPS v 21.0 Results: Out of 103 students reported a laboratory related musculoskeletal pain in the last 12 months while 16 (15.5%) within 7 days. The lower back (21.4% and 16.5%), neck (13.6% and 9.7%) and shoulders (10.7% and 6.8%) were the most common sites of problems reported within a 12 month and 7 day period respectively. Moreover, feeling of pain or discomfort in lower back, neck and shoulders prevented 18 subjects (17.4%) from performing daily activities while the 10 (9.8%) students required physical assistance during past last year. There was a statistically significant association between WMSP and gender, laboratory activity, and students work position Conclusion: It is concluded that significant number of university biomedical science students experienced musculoskeletal pain during their laboratory training activities which was found to be highly prevalent in upper extremities than lower extremities. Students reported work related musculoskeletal pain during the last 12 months respectively which has affected their daily activities. Few of them also seek medical advice by the health professionals. Students need education and awareness for better seating and safer work postures that may reduce the prevalence of musculoskeletal pain.

An Acoustic Way to Support Japanese Children’s Effective English Learning in School Classrooms

In this paper, the importance of implementing good acoustic conditions in classrooms using sound amplification systems is investigated to support more effective English education for elementary school children. To date, the failure of educating English as a second language at Japanese schools has been demonstrated by poor English conversation ability of those who completed a compulsory six-year English language course at Japanese junior-high and high schools (age 12–18). To amend the situation, teaching English became compulsory at grade three (age 8–9) and above at most Japanese elementary schools in the 2020 academic year. We conducted acoustic measurements of two types of sound amplification systems, a pair of PC loudspeakers and another with a loudspeaker array, in a typical classroom at an elementary school in Japan. We also analysed English listening test results of 216 Japanese native children (age 11–12) who were learning English in their usual classes in Japan, to compare the effects of those two systems. Results of logistic regression analysis adjusted by the discrimination difficulty of word pairs demonstrated the statistically significant association between correct answer rate of the English tests and classroom acoustic factors. Although, on average, upgrading the sound amplification system had positive effects on the correct answer rate, it also had a negative impact when the word pairs had English phoneme contrasts that do not appear in Japanese phoneme structure. Combined with the acoustic measurements’ results, it was also revealed that heterogeneous sound fields that depend on seat positions could be compensated using sound amplification systems with loudspeaker arrays. Our findings suggest that improvement of both acoustic quality and teaching methods is required for children to acquire English communication skills effectively in their classroom.

Student Seating Position and Their Academic Performance in Computer Science Major

A number of studies regarding the correlation between student seating position and their academic performance have been conducted. However, only a few of them focusing on computer science major, which is argued to be unique in terms of teaching style and classroom layout; as the discipline puts more emphasise on hands on activity like programming, system and network configuration. Further, among those works focusing on that major, none of them specifically address undergraduate students. This paper presents an observational study involving 426 computer science undergraduate students. The study covers student activity over one academic semester. A questionnaire survey measuring student awareness about that correlation in their seating preference was also performed, with 126 students as the respondents. In general, the correlation only exists on some circumstances like student major and lecture time. Further, the seating preference can be driven by the awareness of that correlation with some motivating factors like friends, whiteboard position, and personal habit. Per occasion, it is suggested to analyse the class circumstances and the student motivating factors prior performing further actions.&#x0D; Index Terms— seating position; academic performance; observational study; survey instrument; computing education

Motion Responses by Occupants in Out-of-Seat Positions During Autonomous Emergency Braking.

The occupant's posture can be changeable to an inadvertent or unintentional out-of-seat position (OOSP) depend on their convenience. Understanding for OOSP has been demanded, but it is not sufficient; especially when AEB is activated. The aim of the current study was to characterize the motion responses of an occupant in various OOSPs when AEB is activated and to identify if there were any additional risks of injury or discomfort to the occupant. The normal seat position (NSP) and three OOSPs were defined to compare the difference of human responses, and six healthy males were participated. Particularly, the maximum rotation angles of the neck in OOSP2 and OOSP3 differed significantly around 1.3 ± 0.3 and 1.4 ± 0.2 times higher respectively than from in the NSP (p < 0.05). Occupants assuming OOSP3 exhibited motion characteristics were not restrained effectively and characterized a hovering and falling upper body and a slipping pelvis. This study has identified, for the first time, a potential risk of injury or discomfort when AEB is activated while an occupant is in an OOSP. This study may serve as fundamental data for the development of safety system that can improve restraint and counteract any deterioration in occupant safety.

Characteristics of Traffic Accidents on Highways: An Analysis Based on Patients Treated at a Regional Trauma Center

Purpose There have been increasing concerns about serious traffic accidents on highways. The purpose of this study was to analyze factors affecting traffic accidents on highways and the severity of the resulting injuries. Methods This retrospective study was conducted at a regional trauma center. We reviewed 594 patients who had been in 114 traffic accidents on highways from January 2018 to June 2020. We collected demographic data, clinical data, accident-related factors, and meteorological data (weather and temperature). Results Environmental risk factors were found to be significantly associated with the incidence of traffic accidents on highways. Injury severity and the death rate were higher in sedans than in any other type of vehicle. Tunnels were the most common location of accidents, accounting for 47 accidents (41.2%) and 269 injured patients (45.3%). The injury severity of individuals riding in the driver’s seat (front seat) was high, regardless of vehicle type. Three meteorological risk factors were found to be significantly associated with traffic accidents: rainy roads (odds ratio [OR] 2.08; 95% confidence interval [CI] 1.84–3.29; p=0.01), icy or snowy roads (OR 5.12; 95% CI 2.88–7.33; p&lt;0.01), and foggy conditions (OR 2.94; 95% CI 2.15–4.03; p&lt;0.05). Conclusions The injury severity of patients was affected by seat position and type of vehicle, and the frequency of accident was affected by the location. The incidence of traffic accidents was strongly influenced by meteorological conditions (rain, snow/ice, and fog).

Vibration Transmission Characteristics and Detection Method of Bilateral Chain Drive of Multicylinders

The transmission modes of multiple rotating parts on the combine harvester are complex and diverse, and the excitation vibrations are coupled with each other, which makes it difficult to dynamically balance the parallel rotating bodies on-site. In order to obtain the influence of the multicylinder transmission system on the vibration response and transmission characteristics of the whole machine providing an experimental basis for the overall balance of the multicylinder system, this paper tested and analyzed the vibration response and shaft vibration state of the system under different transmission modes. On this basis, the influence of chain drive and different transmission modes on the vibration characteristics of the multicylinder was analyzed. Through the tests of the vibration response of the multicylinder frame, the main transfer path of the vibration of each excitation source was analyzed. The results showed that the transmission chain and transmission mode would affect the stiffness, damping, and vibration response of the cylinder fundamental frequency of the chain transmission system on both sides of the multicylinder. The contribution rate of different transmission modes and rotation speeds to the vibration at the fundamental frequency of the multicylinder was 5%∼30%, which would also cause the deflection angle of the roller axis track to change from 1° to 5°. The frame was the main path of vibration transmission of bilateral chain drive of the multicylinder system, and the vibration transmission efficiency of the frame under different frequencies can reach more than 80%. In addition, the vibration response of each cylinder would also be transmitted to each bearing seat position of the multicylinder through the frame.

Modelling and ride comfort analysis of a coupled track-train-seat-human model with lateral, vertical and roll vibrations

A coupled track-train-seat-human model with lateral, vertical and roll vibrations was developed to investigate the ride comfort of high-speed trains. The ride comfort was assessed by the total equivalent acceleration defined according to ISO 2631-1. It was found that the track flexibility had a minor influence on the lateral, vertical and roll floor vibrations below 20 Hz, while the total equivalent acceleration was overestimated by over 10% at high speed using a rigid track. The flexibility of the carbody generated dramatic floor vibration in lateral, vertical and roll directions above 7.5 Hz, so the rigid carbody model significantly underestimated the total equivalent acceleration. The total equivalent acceleration tended to increase with the increase of speed. The equivalent accelerations for two symmetric seat positions illustrated analogous trends with the increasing speed. The ride comfort was the worst close to the carbody ends, followed by the carbody centre at high speed. The vertical acceleration on the seat pan was the most severe whatever the seat position and speed are. The neighbouring subject brought about a reduction of the total equivalent acceleration for the subject under evaluation. The carbody damping can reduce the total equivalent acceleration effectively in the whole speed range.

Effect of an inverted seated position with upper arm blood flow restriction on measures of elbow flexors neuromuscular performance.

PurposeThe objective of the investigation was to determine the concomitant effects of upper arm blood flow restriction (BFR) and inversion on elbow flexors neuromuscular responses.MethodsRandomly allocated, 13 volunteers performed four conditions in a within-subject design: rest (control, 1-min upright position without BFR), control (1-min upright with BFR), 1-min inverted (without BFR), and 1-min inverted with BFR. Evoked and voluntary contractile properties, before, during and after a 30-s maximum voluntary contraction (MVC) exercise intervention were examined as well as pain scale.ResultsInversion induced significant pre-exercise intervention decreases in elbow flexors MVC (21.1%, = 0.48, p = 0.02) and resting evoked twitch forces (29.4%, = 0.34, p = 0.03). The 30-s MVC induced significantly greater pre- to post-test decreases in potentiated twitch force ( = 0.61, p = 0.0009) during inversion (↓75%) than upright (↓65.3%) conditions. Overall, BFR decreased MVC force 4.8% ( = 0.37, p = 0.05). For upright position, BFR induced 21.0% reductions in M-wave amplitude ( = 0.44, p = 0.04). There were no significant differences for electromyographic activity or voluntary activation as measured with the interpolated twitch technique. For all conditions, there was a significant increase in pain scale between the 40–60 s intervals and post-30-s MVC (upright<inversion, and without BFR<BFR).ConclusionThe concomitant application of inversion with elbow flexors BFR only amplified neuromuscular performance impairments to a small degree. Individuals who execute forceful contractions when inverted or with BFR should be cognizant that force output may be impaired.

How do novel seat positions impact usability of child restraints?

Autonomous driving technology and changes in regulations may create an environment that allows novel vehicle interiors. It is important to consider impact on all types of passengers when contemplating interior design, particularly for vehicles that may be used by families with children. We developed a fixture that enables us to change the orientation of each of 4 car seats and used it to simulate three different vehicle interiors. Ten families with children aged 3 months to 7 years interacted with each of the simulated interiors as part of a usability study. Times to install and remove child restraint systems were not significantly different across the three simulated vehicle interiors, but parents were able to release children fastest when using the “X” configuration, which had all seats on a diagonal facing the middle of the vehicle. While overall experience ratings didn’t differ significantly, seven out of ten parents indicated that they liked the “X” configuration better than the other two configurations tested. Reasons included: ability to interact with other passengers, ability to see the road, and legroom/comfort. However, many participants disliked having some passengers not facing forward. Overall, parents liked facing their children, but several said that they would only be comfortable if they could see out of the front windshield; meanwhile, children liked seeing their parents’ faces but also preferred to face forward. Child restraint system and vehicle manufacturers could benefit from considering this study when designing new products.

078 Chronic sleep and circadian disruption differentially affects blood pressure, renal sodium retention, and aldosterone secretion

Abstract Introduction Chronic sleep restriction (CSR) and recurrent circadian disruption (RCD; e.g., rotating shiftwork) can increase an individual’s risk of cardiovascular and kidney disease. However, no study has assessed whether CSR and RCD together increase blood pressure (BP) and alter renal function (RF). We tested the hypotheses that the combination of CSR and RCD would increase blood pressure, renal sodium retention, and aldosterone secretion in individuals living for 3 weeks on an imposed non-24-h sleep-wake (SW) schedule (induces RCD) and controlled diet with or without CSR. Methods Seventeen (9M) healthy participants (aged 26.1±4.5y [mean±SD]) were scheduled to twenty-four 20-h Forced Desynchrony days and were randomized to either Control (1:2 sleep:wake, 6.67h sleep:13.33h wake; n=8) or CSR (1:3.3 sleep:wake, 4.67h sleep: 5.33h wake; n=9) SW conditions during a 32-day inpatient protocol. BP was measured following ~80–90 min in constant seated posture after scheduled waketime. All urine voids were collected, combined and sampled in 3-6h blocks throughout the study. Samples were assayed for sodium, potassium and aldosterone and analyzed as both excretion rates and total secretion (both per 20h). Data were assigned circadian phase using fitted core body temperature and analyzed using mixed-effects models with circadian phase, aligned/misaligned sleep, or time awake (with associated scheduled activity, sleep/wake, and feeding behaviors) and their interactions as fixed effects. Results There was a significant interaction between aligned/misaligned sleep and condition for resting BP (p=0.02), such that systolic BP was ~6% higher following circadian-misaligned sleep in CSR compared to Control (p=0.04). Renal sodium and potassium followed a robust circadian pattern (p&amp;lt;0.0001), with limited influence of time awake. In contrast, the timing of aldosterone excretion was affected by time awake (p&amp;lt;0.05). Total daily renal sodium secretion decreased from beginning to end of the protocol (p=0.03), with no change in sodium consumption and aldosterone secretion (p=0.95). Conclusion Under conditions similar to rotating shiftwork, systolic BP increased and sodium, potassium, and aldosterone were differentially influenced by circadian phase and scheduled behaviors. Additionally, renal sodium secretion decreased despite minimal changes in aldosterone secretion, suggesting increased renal aldosterone sensitivity. These findings may provide insight into mechanisms contributing to poor cardiovascular and renal health observed in shiftwork. Support (if any):

A Study on the Use and Misuse of Child Restraint System (CRS) in Malaysia

&#x0D; &#x0D; &#x0D; In car crashes, children are more likely to suffer more severe injuries than adults. For prevention, Child Restraint System (CRS) is normally used. However, inappropriate use of CRS may exacerbate injury risks. This research aims to determine the prevalence of CRS use and misuse among car owners, especially those travelling with children aged 11 years and below. A total of 178 parents were interviewed and 267 children were observed. Overall, only 12.7% children were properly restrained in CRS for their size, with the correct installation and appropriate seating position. Prior to CRS law implementation, initiatives such as awareness campaigns, community based programs and CRS clinics should be introduced.&#x0D; &#x0D; &#x0D;

Differences in maximal inspiratory pressure when using a standard yoga mat versus a standard yoga block in healthy individuals

Background Yoga, which incorporates posture optimisation and specific breathing techniques, is recognised for its health benefits including musculoskeletal strengthening, stress relief and respiratory enhancement. It is therefore becoming an increasingly utilised practice within the medical environment, specifically for those with respiratory dysfunctions such as chronic obstructive pulmonary disease (COPD). The relationship between posture and yoga and the potential impact upon breathing is an important topic to study for its potential health benefits. This study compares the impact of two different yoga seating positions on respiratory muscle strength. Methodology Eighteen students from Cardiff University between the ages of 19–34 years were recruited via convenience sampling. Each was in good health, with body mass index (BMI) in the normal category and possessed no respiratory infection or significant spinal deformities. Participants were required to sit comfortably, cross-legged for 2 minutes in each sitting position, before three measurements of maximal inspiratory pressure (MIP) were taken. Analysis was performed on the highest result in each position using Statistical Package for the Social Sciences (SPSS) version 25. Comments on comfort levels were given spontaneously and, despite not being a primary aim of the study, provided an interesting discussion point. Results and conclusions Sitting on a yoga mat produced higher mean MIP figures (104cm H2O) than the yoga block (100.39cm H2O), p = 0.015. Despite statistical significance, the mean difference of 3.61cm H2O is unlikely to have clinical significance as it is small compared to the observed MIP range (&gt;90 cm H2O). There does not appear to be a recognised minimum clinically important difference in the literature, making interpretation difficult.

Examining Students’ Challenges in Oracy in Academic Context Classes

This study identifies challenges perceived by Indonesian students of English as a Foreign Language in Oracy in Academic Context classes as well as possible causes of the problems. This subject was a new addition to the 2018 curriculum of the English Department of Teacher Training and Education Faculty at XXX University in Indonesia. The findings show the main problems students faced related to speaking issues, for example, lack of self-confidence, fear of making mistakes, ineffective class schedule, annoying audience behaviour, lack of vocabulary, lack of grammatical precision, poor pronunciation, difficult and uninteresting topics, direct or immediate corrective feedback, and problems coordinating group work. The students also pointed out that as listeners they perceived difficulties due to their lack of adequate background knowledge, unfamiliar vocabularies, anxiety, speakers’ poor pronunciation, too fast or too long presentations, accents, clarity of the sound, seat positioning, room temperature, lack of concentration, and indifferent speakers. Based on analysis of the data, these problems are induced by several factors which include lack of linguistic proficiency, variable cognitive competencies, physical conditions, and most prominently psychological, social and emotional challenges. A set of recommendations to address these issues is also presented in the following paper. Â

The efficacy of a lifting strap as an ergonomic intervention for EMS providers: Does it make it easier to raise a supine patient to an upright sitting posture?

Patient handling related musculoskeletal injuries are prevalent among Emergency Medical Service (EMS) providers. The first step in many patient handling situations is where a supine patient on the floor is brought to a sitting position. This study investigated whether a strap, placed under the patient's torso and long enough that EMS providers can perform the patient raising task in a standing posture, reduced muscular effort. Fifteen participants raised a simulated patient, with the help of an assistant, using the strap method and a traditional method (grasping the shoulders) in an open area, a restricted space, and in a bathtub. Torso postures improved in all location conditions when using the strap. The muscle activation data showed mixed results. While EMG responses from the latissimus dorsi muscles were reduced, EMG activity of the erector spinae muscles increased when the strap was used. Perceived effort assessments supported the use of the strap.

Design of a linear motor-based shaker rig for testing driver's perceived ride comfort

In autonomous vehicles the driver will become a passenger. By ensuring a high level of ride comfort through active suspensions, the driver's ability to perform various tasks such as reading, drawing and texting can be enhanced. A high-performance shaker rig can conveniently be used to test the ride comfort improvement by means of various active suspensions under laboratory conditions. The paper deals with the design of such a rig, which employs a linear electric servomotor to impose accurately controlled vertical vibrations of driver seat. The reference time profiles of seat acceleration, velocity and displacement are generated off-line by using a half-car vehicle model and LQR control with a road preview option. The selection of linear motor comes from assessment of three characteristic shaker rig drive designs (hydraulic and two electric ones). To ensure high-precision seat motion, the proposed shaker control system includes: acceleration feedforward and feedback control loops, a state controller-like compensator of accelerometer offset to prevent drift of seat position and velocity, and feedforward compensation of linear motor cogging force mode. The designed shaker rig application is demonstrated through a case study related to ride comfort evaluation of various active suspension configurations and a drawing task. The drawing task results are employed to determine the root-mean-square vertical seat acceleration threshold, below which the active suspension drawing task performance remains similar to that obtained under standstill conditions.