Search

Copyright of Journal of Shanghai Jiaotong University (Science) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The design of vehicle cabin seats is crucial in transportation, as it directly affects the safety and comfort of both drivers and passengers. To design seat parameters that enhance sitting comfort, a quantitative evaluation of sitting comfort involving an understanding of users' physiological responses is necessary. This study aimed to assess users' physiological responses to relaxation induced by changes in seat parameters using electroencephalography and electrocardiography. We examined the physiological responses and subjective evaluations of relaxation in fifteen participants, focusing on the effects of reclining, ottoman, and slab. The results demonstrated an improvement in the subjective level of relaxation with changes in all seat parameters set here. However, central nervous system responses and autonomic nervous system reactions varied based on alterations in posture angles and seat pressure distributions. This underscores the importance of physiological markers, encompassing indicators of autonomic and central nervous system responses, in evaluating relaxation in relation to changes in posture angles and seat pressure distribution. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology is the property of Automobile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The design of vehicle cabin seats is crucial in transportation, as it directly affects the safety and comfort of both drivers and passengers. To design seat parameters that enhance sitting comfort, a quantitative evaluation of sitting comfort involving an understanding of users’ physiological responses is necessary. This study aimed to assess users’ physiological responses to relaxation induced by changes in seat parameters using electroencephalography and electrocardiography. We examined the physiological responses and subjective evaluations of relaxation in fifteen participants, focusing on the effects of reclining, ottoman, and slab. The results demonstrated an improvement in the subjective level of relaxation with changes in all seat parameters set here. However, central nervous system responses and autonomic nervous system reactions varied based on alterations in posture angles and seat pressure distributions. This underscores the importance of physiological markers, encompassing indicators of autonomic and central nervous system responses, in evaluating relaxation in relation to changes in posture angles and seat pressure distribution.

Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background In today’s economy, workers spend increasingly more time in seated positions, leading to a growing scientific interest in chair design. In this study we used body pressure distribution tests to compare a novel bamboo chair with unique structural features to other commonly-used chairs. We studied the bamboo sheet chair’s physical characteristics and comfort to provide a scientific theoretical basis for common use seat design. Methods A total of 25 (14 male and 11 female) subjects participated in the study. Subjects were divided into six groups according to their body characteristics parameters included stature, weight, shoulder breadth, hip breadth, waist width, popliteal height, buttocks-popliteal length, and buttock-abdomen depth, with three groups for males and three groups for females. Each subject was required to complete specified body pressure tests for three different experimental chairs for three minutes and subjective comfort evaluations were also administered. The pressure indexes were measured from the seat pan and backrest and calculated with MATLAB 2015b, which mainly included maximum pressure (Pm), average pressure (Pa), pressure exponent (Pe) and contact area index (PAI). Three pressure threshold limits of 0.67 kPa, 4.00 kPa and 9.33 kPa and four contact surface indexes were used in the experiment to reflect the contact area between human and chair. Results The contact areas in the backrest (52.96 ± 32.94 cm2) and seat pan (307.75 ± 90.31 cm2) in the middle-to-high threshold pressure range, and the contact areas of the backrest (4.34 ± 5.95 cm2) in the high threshold pressure range of bamboo sheet chair were smaller than the corresponding indexes of the common office chair (81.430 ± 45.04 cm2, p = 0.00; 394.39 ± 98.99 cm2, p = 0.02; 13.54 ± 12.00 cm2, p = 0.00, respectively). The pressure index (2.68 ± 0.88 kPa), maximum pressure (6.66 ± 2.05 kPa), and average pressure (2.42 ± 0.59 kPa) values of the bamboo sheet chair backrest were also found to be lower than those of the office chair (4.32 ± 1.62 kPa, p = 0.00; 10.50 ± 3.88 kPa, p = 0.00; 3.43 ± 0.97 kPa, p = 0.00, respectively). The average pressure on the seat pan was greater than 4 kPa for all subjects, while the average pressure on the seat pan was greater than 9.33 kPa for male subjects with a body mass index (BMI) of 27.48. Discussion The bamboo sheet chair’s contact areas within the middle-to-high and high-pressure threshold ranges of the backrest and seat pan were smaller than those of the office chair, indicating that the bamboo sheet chair is effective at relieving pressure. Human body characteristics must be considered in the design of seat functional size. Buttocks-popliteal length, weight, body mass index, body shape and weight distribution, all have important effects on the distribution of body pressure at the human-chair interface.

Person has spent most of the day in a sitting posture. In recent years, there has been a growing attention to the "seating comfort" researches. However, research topics are complicated and vary widely, it is difficult for a designer to use accurately design knowledge during the development of chairs. Therefore, in this study, "seating comfort" researches based on the literatures were systematically analyzed by the elements extracted and classified into spaces of element inter-relationship diagram using Multispace design model. Extracted elements were classified and discussed about change based on timeaxis. And, also the literatures categorized using cluster analysis of the extracted elements. From consideration based on the analysis results, researches about the human mechanism of seating comfort and long-term sitting analysis including the postural change have been proposed as non-research areas for future knowledge expansion.

The whole-body comfort sensation was moderately to highly correlated with local body part comfort sensation in both sitting and driving, in order to understand what exact relationship exists between them, the seating comfort evaluations under the stimulus of four body parts (i.e. backs, waist, hips and thighs) were carried out for 15 subjects separately, subjective ratings on both partial-body and whole-body comfort are derived under different conditions. Impact factor (IF) of the partial-body comfort to whole-body comfort is calculated by the linear regression method, and the main variables are obtained by the stepwise regression algorithm. The most significant local body part in influencing whole body comfort is found at the region of hips, followed by backs, waist and hips. With impact factor analysis on partial body comfort, the results show that the local comfort feeling of waist is most potential to be influenced by other body parts, while the comfort sensitivity of thighs is the lowest. [ABSTRACT FROM AUTHOR]

This literature review focused on passenger seat comfort and discomfort in a human–product–context interaction. The relationships between anthropometric variables (human level), activities (context level), seat characteristics (product level) and the perception of comfort and discomfort were studied through mediating variables, such as body posture, movement and interface pressure. It is concluded that there are correlations between anthropometric variables and interface pressure variables, and that this relationship is affected by body posture. The results of studies on the correlation between pressure variables and passenger comfort and discomfort are not in line with each other. Only associations were found between the other variables (e.g. activities and seat characteristics). A conceptual model illustrates the results of the review, but relationships could not be quantified due to a lack of statistical evidence and large differences in research set-ups between the reviewed papers. Practitioner Summary:This literature review set out to quantify the relationships between human, context and seat characteristics, and comfort and discomfort experience of passenger seats, in order to build a predictive model that can support seat designers and purchasers to make informed decisions. However, statistical evidence is lacking from existing literature. [ABSTRACT FROM PUBLISHER]

The increasing time period people spend in sitting position presents several risks of suffering musculoskeletal disorders. The main objective of this research was to raise awareness for prolonged sitting students about negative consequences of the incorrect seat. In the mainframe of the research the body pressure distribution of different body shaped students in diverse postures were measured on the most frequently used chairs in university's lecture halls and laboratories. The recorded pressure maps were analysed from sitting comfort aspects thereafter and suggestions for correct sitting postures formulated finally. Research data and analysis revealed that most of the subject sit asymmetrically on chairs, the difference between left and right sides can reach 25%, the body built and sitting posture has a significant influence on the pressure distribution and peak pressures in the selected zones. Beside to a comfortable seat a special attention should be paid also to a correct posture, because many of health complains can be linked to the latter. [ABSTRACT FROM AUTHOR]

Construction of the seat and back of the office chair, as an actual object of the human working environment, is important in its final design since these are the elements that are in a direct and close contact with human body. The sitting position is the most frequent working position of the modern man in the developed world. Independently of the type of work, a sound and physiologically correct sitting position diminishes fatigue during work and strain of the spine, and suitable posture during sitting significantly contributes to the increase of concentration and efficiency. Sitting as a working position can be examined through coordination of anthropometric sizes and form of the seat and back, or mechanically, by determining the relation between the user and the seat quality, where the comfort index or support factor has a great influence. The comfort index as one of the factors of sitting comfort is the result of mechanical characteristics of the observed chair. This paper shows the results of ‘’mechanical comfort’’ that the chair can offer to the user. The results of determining the seat comfort on office chairs are featured through comfort index obtained from elastic characteristics of materials in the seat, but also of the chair itself according to Technical Specifications HRS ENV 14443.

Most research on product comfort focuses exclusively on the use of the evaluated product (e.g., Kyung, Nussbaum, & Babski-Reeves, 2008; Harih & Dolšak (2013). We sought to investigate the influence of a sitting precondition on ratings for first impression of comfort, short-term comfort, and discomfort of a product. The aim was to assess if and how sensations experienced prior to product use affected product evaluation. Therefore, a vehicle seat was evaluated with two preconditions in a within-subjects design. The comfort model of Vink and Hallbeck was extended according to the findings of this study. [ABSTRACT FROM AUTHOR]

Copyright of Wood Industry / Drvna Industrija is the property of Drvna Industrija and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This is the first study to report on hip range of motion (ROM) among active prosthesis users, when wearing and not wearing a trans-femoral socket prosthesis and to compare with individuals rehabilitated with an osseointegrated bone-anchored prosthesis. In addition, discomfort when sitting with the prosthesis is reported in both groups. The study group all had a non-vascular amputation and were divided into those supplied with a socket prosthesis (S group) (n = 43, mean age 51 years, 74% men) or a bone-anchored prosthesis (OI group) (n = 20, mean age 46 years, 75% men). Active hip ROM was measured with a goniometer, and self-reported problems with discomfort when sitting were recorded. The hip motion decreased in all directions when wearing the socket prosthesis compared to without it (P < 0.001 for all directions), and 37% of the subjects had less than 90 degrees of hip flexion when wearing their prosthesis. Discomfort when sitting was reported among 44% (n = 19) in the S group and was more common among individuals with less than 90 degrees of hip flexion motion (P= 0.025). In the OI group, no restriction in hip motion was measured with the prosthesis, and no subject had less than 90 degrees of flexion and 5% (n = 1) reported discomfort when sitting. This study shows that a trans-femoral prosthetic socket significantly reduces the ROM of the hip and that discomfort when sitting is common among individuals wearing such prostheses. Further, the study confirms that individuals using a bone-anchored prosthesis have no restricted hip motion with the prosthesis and report very few problems with discomfort when sitting. [ABSTRACT FROM AUTHOR]

This study examined postural variabilities based on the self-perceived most comfortable postures of 12 participants (six men and six women) when sitting on three commonly used types of chairs (a stool, computer chair, and gaming chair). Participants' global joint angles were recorded and analyzed. Of the chairs studied, the stool was not adjustable, but the computer and gaming chairs were moderately and highly adjustable, respectively. During the test, participants were encouraged to adjust the chairs until they perceived that the most comfortable posture had been reached. The results demonstrated that in a sitting position perceived to be comfortable, the participants' postural variabilities with respect to global joint angle, calculated from five repetitions, were unexpectedly high for all three chair types, at approximately 9.4, 10.2, and 11.1° for head inclination, trunk angle, and knee angle, respectively. The average differences in range for each joint angle among the three chair types were relatively low, with all values within 3°. The result also showed that gender (p < 0.01) and chair type (p < 0.001) significantly affected trunk angle, whereas these variables did not affect head inclination or knee angle (p > 0.05). The preliminary results observed unexpectedly high variabilities in sitting posture when the participants sat at a posture that they perceived to be the most comfortable. The findings also indicated an inherent difference in comfortable sitting posture between genders; women tend to extend their trunk backward more than men. For permanent use with only an initial adjustment and memory-aided seat design, designers should minimize the loads that are borne by body parts over a prolonged period due to an unchanging sitting posture. [ABSTRACT FROM AUTHOR]

In order to evaluate sitting comfort qualitatively, a flexible and very thin sensor was developed to measure the contact shape between a seated man and the seal surface. Each tape has twenty strain guages on it at regular intervals, and the fourteen tape sensors were arranged on the bottom and back surface of the experimental driver's seat. The contact shapes and postures in thirty two male drivers were measured with two types of seal cushion and sitting posture: free and recommended. Sensory evaluation was made for each experimental condition. The results of the interrelation between the characteristics of the surface deformation, the parameters of body build, sitting posture and feeling of comfort shows that the comfort of each morphological fitting does not correspond to one special and single parameter from those physical factors, but is represented by a function with many parameters related to the deformation, posture and body build. By using these relations, a sensory model for the prediction of the sitting comfort was constructed. [ABSTRACT FROM PUBLISHER]