Mechanism Analysis of the Influence of Seat Attributes on the Seat Dip Effect in Music Halls

The seat dip effect (SDE) is an acoustic phenomenon of low-frequency band attenuation that occurs in the music halls when the sound of the music passes at a near grazing incidence over the seats. In this paper, the numerical simulations on the basis of the finite element method are conducted to study the influence of seat attributes (seat height, seat spacing and seat absorption) on the SDE and the corresponding mechanism. The mapping of sound spatial distribution related to the SDE is employed to observe the behavior of sound between the seats. The results show that the dip frequency of the SDE can be shifted to frequencies lower than theoretical values when the seat height is smaller than the seat spacing. Additionally, the SDE attenuation can be distinctly suppressed in a sequence from the front seats to the rear seats with an absorption improvement to the seat back or cushion, and the seat back absorption is more effective than the cushion absorption. A mechanism analysis reveals that the SDE is highly associated with standing waves inside the seat gaps and with the “diffusion” effect on the grazing incident waves by energy flow vortexes around the top surfaces of the seats.

Garments furniture design for Bangladeshi workers considering ergonomic principles

BACKGROUND: In Bangladesh, workers typically spend at least eight hours a day at garment factories in sitting and/or standing position. Prolonged sitting on ergonomically unfit furniture causes back, neck, and shoulder pain, which reduces the working efficiency and leading to low productivity. OBJECTIVE: The aim of this study is to design ergonomically correct furniture for Bangladeshi garment workers considering multivariate analysis on the anthropometric data. METHODS: Twelve anthropometric measures and five furniture dimensions were measured. The sample comprised of 600 volunteer workers from different garment industry. The furniture dimensions were compared with the relevant anthropometric characteristics and found a high level of mismatch (e.g. seat height (male 18%, female 94.25%), seat depth (male 96%, female 63.50%), seat width (male 9.50%, female 36.25%), sewing table height (male 56.50%, female 50%), and desk height for inspection, cutting and ironing table (male 100%, female 100%). RESULTS: New design specifications were proposed of the worker which improved the match percentage. The multivariate anthropometric analysis generated 8 cases and for each case the ranges of anthropometric measurements have been identified. CONCLUSION: The results will help to design robust ergonomic garments furniture.

Covid-19. Diseño antropométrico de silla y escritorio para recibir clases de posgrado en línea.

Introduction. The Covid-19 pandemic toppled the global economy and common ways of working, forcing students and teachers to take classes online in conditions that are not ergonomically suitable for their health. Objective. Anthropometrically design a chair and desk for a group of students receiving online graduate classes and mitigate ergonomic risk. Methods. It began by determining the real dimensions of the main anthropometric elements that determine a group of professionals who study online and then applying percentile calculations to choose the best dimension of 14 parts of a chair and a desk that mitigates the level of ergonomic risk. Results. From the application of the calculation of the percentiles for a population of 35 students considering a class mark (m) of 6 for 14 anthropometric dimensions that coincide with 14 important parts of the design, the following dimensions were chosen: seat height 42.49 cm, space between legs and table 17.39 cm, seat depth 44.68 cm, table height 53.93 cm, armrest height 22.81 cm, upper back width 43.49 cm, table top depth 60 , 17cm, bottom table depth 70.43 cm, distance allowing mobility 93.64 cm, width of seat base 38.91 cm, distance between armrests 45.88 cm, height of seat back 60.93 cm . Conclusion. An ergonomic workspace was designed considering real anthropometric dimensions for a group of graduate students studying in teleworking conditions due to the Covid-19 pandemic.

ERGO - EVALUATION OF URBAN BUS DRIVER’S WORKSTATIONS IN SOUTH WEST NIGERIA

This study evaluated the ergonomic performance of drivers’ workstations in southwest Nigeria. Fifty urban buses selected from ten brands were investigated by direct measurement. The buses were mini-A and midi-B. Vertical and horizontal distances of the seat reference point to the pedal and steering wheel, with the seat dimensions were considered. The anthropometric dimensions of 150 male bus drivers were taken from South-west Nigeria. The results revealed that the values for driver’s seat height from the cabin floor, seat backrest height, seat shoulder level width and low back width were 44.00- 50.00cm, 53.00-58.15cm, 40.00-50.00cm and - 40.15cm respectively as against 39.15- 43.00cm, 38.75-49.49cm, 34.60-43.59cm and 45.73-53.25cm respectively in the urban bus workstations. It is concluded that the drivers’ workstations in the urban buses were not ergonomically fit for the bus drivers since the anthropometric dimension of the Nigerian male bus drivers were not considered in the designing of the buses.

Design and Analysis of an Intelligent Toilet Wheelchair Based on Planar 2DOF Parallel Mechanism with Coupling Branch Chains

Due to the fixed size of the structure or the possibility of only simple manual adjustment, the traditional toilet wheelchair cannot easily be adapted to the size of the user or the toilet. In this paper, a planar two-degree-of-freedom parallel mechanism with coupling branch chains is proposed to enable both seat height adjustment and body posture adjustment of a toilet chair, solving the problems of posture adaptability between the user and the machine, and height matching in the process of using the wheelchair-assisted toilet. The model of the parallel mechanism was designed after analyzing the general rules of posture transformation in the human body before and after the toilet process, and the dimensions of each linkage were then determined according to the constraint conditions. By analyzing the degree of freedom, kinematics, workspace, singularity and position of the center of gravity, the rationality of the design was ensured. The weighted average function was used to find the optimal fixed point of the horizontal moving slider, and the actual trajectory at the end of the single driving mode was close to the ideal trajectory. The experimental results show that the adjustable seat height range is 290~550 mm and the adjustable angle range is 0~90°, which can enable disabled people to use the toilet independently.

Influence of Electrically Powered Pedal Assistance on User-Induced Cycling Loads and Muscle Activity during Cycling

Bicycles with electrically powered pedal assistance (PA) show great potential as ecological alternatives for engine-based vehicles. There is plenty of research available about the influence of various bicycle parameters on cycling technique. Though, to the best of the authors’ knowledge, there is none about the influence of PA. In this study, a recreational bicycle is equipped with PA and unique instrumentation to measure the user-induced loads on seat, steer and pedals. Joint loading is derived in the sagittal plane from inverse dynamics and muscle activity of the lower limbs is recorded with an electromyography system integrated in cycling pants. An experiment is set up, in which volunteers cycle on an athletics track, with a varying level of PA and a varying seat height. An ANOVA is conducted to determine significant differences due to the level of PA and seat height and to analyze the interaction effect. No interaction effect was found and only differences due to the level of PA were significant. Knowledge about the influence of PA provides insights into (i) electric bicycle design; (ii) the usage of electric bicycle for physically challenged people; (iii) the usage of electric bicycles as a rehabilitation tool.

Comparison of Different Variants of the U.S. Army Occupational Physical Assessment Test

ABSTRACT Introduction The U.S. Army Occupational Physical Assessment Test (OPAT) is a pre-enlistment physical employment screening assessment developed to place recruits and soldiers into Military Occupational Specialties (MOSs) based on their physical capabilities in order to optimize performance and limit injury. The OPAT consists of the seated power throw (SPT), strength deadlift (SDL), standing long jump, and interval aerobic run. During the scientific validation of the OPAT, two variants of the SPT and two variants of the SDL were used. Although the OPAT was validated using both variants for each test, U.S. Army scientists and policymakers have received queries regarding how these variants compare to each other. Therefore, the purpose of this study was to compare different variants of the SPT and SDL. Materials and Methods Thirty-two participants (14 male and 18 female) between the ages of 18 and 42 years visited the laboratory on one occasion and performed two variants of the SPT (seated on the ground [the current OPAT standard] versus seated in a chair with a 35 cm seat height) and two variants of the SDL (using a hex-bar [the current OPAT standard] versus using paired dumbbells). Testing order for the different variants was randomized. The protocol was approved by the U.S. Army Medical Research and Development Command Institutional Review Board. Results Performing the SPT from a chair significantly (P < .05) increased performance when compared to performing the SPT from the ground (5.4 ± 1.3 m versus 5.0 ± 1.4 m, respectively). Values for the two SPT variants were correlated (tau = 0.90). Performing the SDL using the hex-bar significantly increased the maximal weight lifted when compared to performing the SDL using paired dumbbells (86.9 ± 18.4 kg versus 83.1 ± 18.0 kg, respectively). Values for the two SDL variants were correlated (tau = 0.83). Conclusions Performing different variants of the SPT and SDL influenced the resulting score. Although these findings do not alter the administration or scoring of the OPAT, they do provide a valuable reference in the event of future inquiries regarding the development of the OPAT.

A Novel Design of Ergonomic Ablution Place at Mosques in Arar, Saudi Arabia

Currently, there are hardly any uniform design specifications for the construction of ablution places at mosques in Saudi Arabia. Designs of ablution places are usually copied from designs of ablution places in other mosques or based on individual perspectives. Based on the researchers’ anecdotal observations, most of these designs are nonergonomic, uncomfortable, and less user-friendly for ablution in either sitting or standing position, especially for the elderly. In such designs, water splashing is common because of inappropriate heights of platforms or seats, insufficient distances between seats and faucets, and improper shapes and depths of water drain. The purpose of the present study is to present the design of a novel ergonomic ablution place to ensure comfortable, safe, and hygienic conditions. The design is particularly related to the size and height of seat, height and distance of faucet from the seat, depth and slope of water drain, and height and width of the platform. The design was implemented at four mosques in Arar, Saudi Arabia. Modifications at ablution places were made according to the proposed design and were appreciated by the local community. The design was communicated to the Directorate of Mosques in Arar and agreed upon for implementation in other mosques.

A multifactorial approach to specify comfortable rail seats

BACKGROUND: A robust rail seat comfort assessment can inform the GB rail industry when procuring new seats and identify areas for comfort improvement in the refurbishment of existing seats, improving the customer experience. OBJECTIVE: To take a multifactorial approach to measuring comfort and to create a robust seat comfort assessment method for the GB rail industry. METHODS: Seat comfort assessment scores were developed by identifying seat dimensions (e.g. Seat height, seat width, seat depth), seat pad thickness and hardness requirements, seat accessories and seat attractiveness components. Scores for each seat feature were verified by conducting a fitting trial and asking 7 participants to rank dimensions through a range of adjustment. The combined scoring of features was verified by asking 14 participants to rank seats in three configurations (<minimum comfort; minimum comfort;>minimum comfort). The seat comfort dimensions scores were then validated by ranking seven existing rail seats using the assessment method and comparing the ranks with subjective comfort ranks of 12 participants. RESULTS: The validation testing resulted in a moderate positive correlation, indicating an alignment between the seat comfort assessment method and subjective comfort scores. CONCLUSIONS: A multifactorial seat comfort assessment has been shown to be a good indicator of passenger seat comfort.