Impact of lighting environment on human performance and prediction modeling of personal visual comfort in enclosed cabins.

Enclosed cabins are of great significance in various fields, including national defense, scientific research, and industrial applications. It is important to clarify the impact of the lighting environment in these cabins on the people operating within them. This study investigated the effects of the lighting environment in enclosed cabins on the physiological, operational, and comfort performance of operators through simulated experiments. In Addition, using the Random Forest Algorithm and ExpandNet technique, we developed a prediction model to evaluate the comfort level of the lighting environment for personnel in enclosed cabins. The results indicated that pupil diameter exhibited the highest sensitivity to ambient light. The appropriate luminance combination of the screen and the ambient scene have a positive effect on human performance. In particular, it was observed that the average cognitive performance and comfort of participants tended to be relatively high in the luminance combinations 13, 14, and 15 at CCT 5500 K. The screen luminance of these combinations are all 284.75 cd/m2. Although no statistically significant relationship was found between the cognitive performance of the participants and their comfort, the comfort of the participants tended to decrease after the cognitive operations was completed. According to the proposed personal comfort prediction model, the visual comfort of different people varies even under the same lighting conditions. This study provides a solid theoretical basis for improving the design of lighting environments in enclosed spaces and contributes to developing a pleasant and productive working environment within limited cabins.

An evaluation method for HMI of deep-sea manned submersible based on human reliability.

Improving the human reliability of the human-machine interface (HMI) of deep-sea manned submersible is of great importance for the development of the deep-sea field. Based on the SHEL (Software S, Hardware H, Environment E, Liveware L) model, this study classifies the performance shaping factors (PSF) that affect the human reliability of submersible HMIs and builds a PSF system. The interpretative structural model (ISM) is used to matrix the interactions between the elements that make up the system of PSF. A multi-level recursive structure is obtained by building the corresponding adjacency matrix. The Noisy-OR model is introduced to construct a Bayesian network in order to build a new HMI evaluation method. A real case of Bayesian network causal inference verifies the validity of the built method. This study proposes a set of HMI human reliability evaluation methods applicable to deep-sea manned submersible, which provides a new idea for human reliability assessment.

Assessment of Vigilance Level during Work: Fitting a Hidden Markov Model to Heart Rate Variability.

This study aimed to enhance the real-time performance and accuracy of vigilance assessment by developing a hidden Markov model (HMM). Electrocardiogram (ECG) signals were collected and processed to remove noise and baseline drift. A group of 20 volunteers participated in the study. Their heart rate variability (HRV) was measured to train parameters of the modified hidden Markov model for a vigilance assessment. The data were collected to train the model using the Baum-Welch algorithm and to obtain the state transition probability matrix A^ and the observation probability matrix B^. Finally, the data of three volunteers with different transition patterns of mental state were selected randomly and the Viterbi algorithm was used to find the optimal state, which was compared with the actual state. The constructed vigilance assessment model had a high accuracy rate, and the accuracy rate of data prediction for these three volunteers exceeded 80%. Our approach can be used in wearable products to improve their vigilance level assessment functionality or in other fields that have key positions with high concentration requirements and monotonous repetitive work.

Lighting environmental assessment in enclosed spaces based on emotional model.

Lighting assessment in special operating environments like enclosed spaces is of great research significance and value. In addition to investigating the visual ergonomics of workers, the emotional monitoring and guidance of workers in enclosed spaces is also a research focus. Based on the Circumplex emotion model theory, this paper designs an experiment to assess emotions in an enclosed space with 6 different lighting settings (2 correlated color temperature (CCT) × 3 illuminance levels). From the perspective of subjective assessment, participants used a rapid sensory analysis method (Check-all-that-apply, CATA) and a Subjective Coordinate Scale (SCS) method for rapid ambience perception checking and emotional self-reporting of lighting settings. From the perspective of objective evaluation, the participants' facial expressions were recorded during the experiment using a camera, and then the recorded facial expressions were automatically analyzed and predicted using FaceReader (FRE) software. The CATA and SCS showed similar results, with the 3100 K × 600 lx, 3100 K × 1000 lx and 6500 K × 600 lx lighting settings creating a relaxed, pleasant emotion in participants, the 6500 K × 1000 lx setting creating an excited, tense atmosphere, and the low illumination level settings of 3100 K × 250 lx and 6500 K × 250 lx made participants feel tired and frustrated. The results of the objective emotion analysis indicate that the FRE was able to effectively identify differences in participants' emotions in response to different lighting settings and was consistent with the results of participants' subjective emotion reports. This laboratory study validates that the three methods can effectively assess the enclosed space lighting settings, and provides a reference for further research on the enclosed space lighting settings and emotional monitoring of workers in the future.

Effects of aircraft tray table height and neck posture on passenger comfort: A study of the economy class cabin.

BACKGROUND: The tray table in economy class air travel may cause excessive neck flexion and discomfort in passengers. OBJECTIVE: The purpose of this study is to examine the influence of different tray table heights on the neck posture and discomfort perception of passengers. METHODS: A passenger experience survey was used to determine the passengers' view that the tray table was not high enough, and that most passengers were dissatisfied with the overall comfort evaluation of the tray table, especially passengers with obesity. Three head-neck angles and discomfort perceptions of six body parts in 58 participants were recorded by neck posture 3D scanning and perceived level of discomfort assessment, respectively. RESULTS: Tray tables at the original height (68 cm) caused unnatural neck posture and discomfort in participants. Raising the tray table can improve the neck posture of participants and reduce discomfort. However, raising the tray table too high will cause more shoulder discomfort in participants. Based on the results, 78 (±2) cm is suggested as the suitable thresholds range of tray tables for economy class air travel. CONCLUSION: The results and findings of this study could provide a theoretical base for the optimization of tray table design.

Oceanaut's personal acoustic comfort prediction model and sound environment improvement method in the cabin of a Deep-Sea manned submersible.

In this study, a personal acoustic comfort prediction model (PACPM) for exploring the acoustic comfort of oceanauts in a deep-sea manned submersible cabin was proposed, and an oceanauts' task performance model (OTPM) was constructed in this study. Based on oceanauts' comfort and task performance, the change characteristics in six different pure-noise environments (the sound pressure levels of the noise audio are 40 dB (A), 45 dB (A), 50 dB (A), 55 dB (A), 60 dB (A), and 65 dB (A) respectively) were analysed. An effective method for improving acoustic comfort was proposed. According to the analysis, personal comfort at 40 and 45 dB(A) was higher than that at other noise levels. The oceanaut's comfort and task performance of normal-weight people were significantly higher than those of thin people. Meanwhile, a comprehensive consideration of the demographic characteristics and physiological responses can effectively improve the prediction accuracy of the personnel acoustic comfort. Furthermore, the 45 dB (A) pure-noise environment overlaid with 40 dB(A) fast-paced light music effectively improves oceanauts' comfort. Practitioner summary: This study provides a convenient and available method for analysing acoustic comfort in the cabins of deep-sea manned submersibles, including a quantitative prediction model and an effective method for sound environment improvements. These can be used to improve the comfort, task performance, and working efficiency of manned submersibles.

Investigating the Overall Experience of Wearable Robots during Prototype-Stage Testing.

Wearable robots (WRs) might interact with humans in a similar manner to teammates to accomplish specific tasks together. However, the available data on WR user experience (UX) studies are limited, especially during the prototyping phase. Therefore, this study aims to examine the overall experience of WRs during the prototyping phase based on an exploratory research model. This theoretical model considered usability, hedonic quality, and attitude toward using WRs as key factors in explaining and predicting overall experience. To test the hypotheses inherent in the research model, quantitative empirical research was conducted and the data were analyzed by partial least squares structural equation modeling (PLS-SEM). The results from the PLS-SEM analysis revealed the significance level of correlations between the latent variables in the research model. The exploratory research model was able to explain up to 53.2% of the variance in the overall experience of using WRs, indicating medium predictive power. This research develops a new quantitative empirical research model that can be used to explain and predict the overall experience of interactive products such as WRs. Meanwhile, the model is needed during WR testing in the prototype phase.

Analysis of the auricles and auricular shape types for ear-related wearables: A study of mainland Chinese sample aged 15-79.

BACKGROUND: Comprehension of the complex shape of the auricle and how it differs in terms of factors such as sex, age, and side have become an imperative aspect of the fabrication and service delivery of products that are natural, functional, and healthy for users. OBJECTIVE: This study was aimed at providing a clear understanding of the anthropometric characteristics based on age, sex, size, and side and shape type of the auricles of mainland Chinese samples. METHODS: Casting and 3D scanning were employed to obtain eighteen auricular measurement variables from 1120 subjects (aged 15-79). Examination of sex-related and bilateral differences were conducted. Furthermore, factor analysis was employed to establish the factors associated with the variations in auricular shape. Also, hierarchical cluster analysis was performed to classify the auricular shapes of individuals. RESULTS: The auricular inclination angle, conchal depth and tragal height did not exhibit any specific trend across the age groups. No significant bilateral difference was observed in both genders. The auricular shapes were classified into five types according to six major factors. CONCLUSIONS: It was observed that measurement variables of the Chinese auricles changed continuously with age, with most of the linear variables exhibiting a steady increase. The apparent strong association between the auricular types and age groups indicate that a person's auricular shape may change with age.

Effects of two recovery methods on the leg muscle fatigue of oceanauts in a manned submersible.

BACKGROUND: The cabin of the manned submersible is a narrow and sealed space. The long-time work of oceanauts is easy to cause muscle fatigue and stiffness, which reduces efficiency. This paper explored the relative more effective way to relieve leg muscle fatigue of the oceanauts in the manned submersible. MATERIAL AND METHODS: Twenty healthy young people with an average age of 24 years were selected as the participants, while the usual natural relaxation and the stretching method proposed by the surveys were selected as the relieve method for muscle fatigue. This study compared the effects of the 2 recovery ways using the electromyography data from the quadriceps femoris and biceps femoris, and the subjective scales. RESULTS: With the support of data of integral electromyogram (iEMG), root-mean-square (RMS), subjective scales, authors finally found that the 2 muscles of the leg are fatigued significantly, and biceps femoris has more accumulation of fatigue. Although the 2 recovery ways have a significant relief effect on muscle fatigue, the stretching method can reduce more muscle fatigue in a short period of time, especially for biceps femoris. The stretching method is advocated for the oceanauts. CONCLUSIONS: The findings suggested that the stretching method was optimal for relieving the muscle fatigue of the oceanauts during the operation. Med Pr. 2022;73(2):95-107.

Effects of variations in the tragus expansion angle on physical comfort for in-ear wearables.

Tragus expansion angle (TEA) is an angular variable that quantifies the outward degree of expansion of the tragus cartilage induced by in-ear wearables (designed with hard materials) fitted into the external ear. It is a physical factor that directly influence user's comfort experience during interaction with in-ear wearables. This study was aimed at quantifying the effects of variations in TEA on physical comfort. TEA was measured and normalised employing a measuring device and Tragus Expansion Index (TEI) proposed in this study. Physical (dis)comfort was assessed using a rating scale designed based on the 5-point Likert and Borg-CR10 scales. Comparatively, the comfort range of variations in TEA was similar for both genders. Males could endure a higher level of variations in TEA compared to females. A quantitative relationship between variations in TEA and (dis)comfort ratings was established using TEI values and GaussAmp function, which can be employed for ergonomic design purposes. Practitioner summary: This study provides an empirical and available source for quantifying the effects of variations in the tragus expansion angle on physical comfort, including quantitative tools and (dis)comfort rating models, which could be used as a reference for improving the fit, comfort and functional capacity of in-ear wearable devices.

A method for designing the longitudinal position of a porthole in a manned submersible based on the back muscle fatigue characteristics.

OBJECTIVES: The proper porthole angle contributes to relieving the operation fatigue and improving the efficiency of oceanauts. In this study, the authors explored the effect of 3 different porthole longitudinal positions on the oceanauts' back muscles using surface electromyography (sEMG) analysis, and the characteristics of the perceived body comfort was obtained. MATERIAL AND METHODS: Overall, 40 healthy participants were recruited to perform tasks in a simulated cabin environment. Electromyographic (EMG) signals were recorded from the trapezius medius, lower trapezius, and erector spinal muscles for porthole angles of -5°, -15°, and +15°, relative to the horizontal line of sight during a 21-minute experiment. The subject comfort scores were collected at 7, 14 and 21 min. The integrated electromyogram (iEMG) and the root mean square (RMS) of EMG signals, as well as the mean power frequency (MPF), and the mean frequency (MF) were calculated. RESULTS: The subjective scores of the +15° porthole at each stage of work are higher than those of the -15° and -5° portholes. The results of iEMG, RMS, MF and MPF all indicated that the +15° porthole design was more conducive to lowering the rate of muscle fatigue, while the -5° and -15° portholes increased the muscle fatigue rate and led to greater fatigue. It was found that the lower trapezius was more prone to fatigue than the trapezius medius and erector spinal muscles. The height, weight and body mass index of the participants were found to negatively correlate with muscles at the +15° porthole, which is highly consistent with the actual situation. CONCLUSIONS: The findings suggested that the +15° position was optimal for delaying the muscle fatigue of the participants and for improving the work efficiency of oceanauts. Int J Occup Med Environ Health. 2021;34(6):701-21.

A Consensus-Reaching Approach to the Evaluation of Product Design Alternatives with Multiple Preference Structures.

With interdisciplinarity being an important characteristic of contemporary product design, the evaluation of design alternatives also involves multiple disciplines, and the evaluator group usually consists of evaluators from different fields and with obvious heterogeneous characteristics. To effectively satisfy the heterogeneous needs of evaluators and improve the credibility of evaluation results, the paper introduces a consensus-reaching approach that incorporates multiple preferences to the evaluation of product design alternatives. First, in order to obtain individual preference information, each evaluator is asked to evaluate all the design alternatives using a preference structure that he/she is familiar with. Second, we use a transfer function to uniform the evaluation information obtained from various preference structures into a complementary judgment matrix. Then, we use the Hybrid Weighted Averaging (HWA) operator weight determination model to aggregate the preference information and obtain the group preference information. Then, we measure the consensus degree between individual evaluators and the group using a consensus measurement method. After that, we use the feedback mechanism to instruct individual evaluators to modify their preferences until a consensus is achieved. We explain the application steps and the feasibility of this approach through the evaluation of the design alternatives of multichannel fluorescence immunochromatography analyzers (MFIAs).

Analysis of the external acoustic meatus for ergonomic design: part I - measurement of the external acoustic meatus using casting, scanning and rapid estimation approaches.

Numerous ear-related wearables require precise measurements of the external acoustic meatus (EAM) to optimise function and comfort. The purpose of this study is to describe a novel methodology for measuring the EAM. A total of 23 measurement variables (18 novel) of the EAM from the entrance to the second bend were collected on 700 Chinese subjects (age: 15-83) using casting and 3D scanning over seven age spans: 10, 20, 30, 40, 50, 60 s and 70+. The ear horizontal plane was identified as a new reference plane for measurements and the medial concha was selected as the reference point for positioning the entrance. A detailed approach to characterising the EAM was developed as was an approach for the rapid estimation of circumference and area using regression equations making it ideal for use in early design conceptualizations. Practitioner summary: This study provides a scalable measurement methodology for determining anthropometric measurements of the external acoustic meatus. The measurement methodology and its application to the design and fitting of ear-related wearables are important to optimising their function and comfort.

Analysis of the external acoustic meatus for ergonomic design: part II - anthropometric variations of the external acoustic meatus by sex, age and side in Chinese population.

For devices worn inside the ear, detailed anthropometric data of the external acoustic meatus (EAM) is needed, yet lacking due to the complex and costly methodology associated with attaining such measurements. The purpose of this study was to provide the anthropometric characteristics of the EAM including variations by age group, sex, and side (right/left). 1400 external ears (700 Chinese subjects) were casted and scanned. A total of 23 EAM dimensions of length, width, angle, circumference and area were measured, most of which changed by age group, sex and side. 19 measurements were larger in males and 17 measurements were larger in left-side ears. Except the entrance length and circumference, measurements were not statistically significant between left- and right-side ears. This study provides key anthropometric measurements of the EAM in a Chinese population which can be used for ergonomic design purposes. Practitioner summary: This study provides an available source for anthropometric variations of the external acoustic meatus by age, gender and side in the Chinese population, which can be used as a reference to improve the fit, comfort and function of in-ear wearable devices.

Bionic Design, Materials and Performance of Bone Tissue Scaffolds.

Design, materials, and performance are important factors in the research of bone tissue scaffolds. This work briefly describes the bone scaffolds and their anatomic structure, as well as their biological and mechanical characteristics. Furthermore, we reviewed the characteristics of metal materials, inorganic materials, organic polymer materials, and composite materials. The importance of the bionic design in preoperative diagnosis models and customized bone scaffolds was also discussed, addressing both the bionic structure design (macro and micro structure) and the bionic performance design (mechanical performance and biological performance). Materials and performance are the two main problems in the development of customized bone scaffolds. Bionic design is an effective way to solve these problems, which could improve the clinical application of bone scaffolds, by creating a balance between mechanical performance and biological performance.

Consumers' Kansei Needs Clustering Method for Product Emotional Design Based on Numerical Design Structure Matrix and Genetic Algorithms.

Consumers' Kansei needs reflect their perception about a product and always consist of a large number of adjectives. Reducing the dimension complexity of these needs to extract primary words not only enables the target product to be explicitly positioned, but also provides a convenient design basis for designers engaging in design work. Accordingly, this study employs a numerical design structure matrix (NDSM) by parameterizing a conventional DSM and integrating genetic algorithms to find optimum Kansei clusters. A four-point scale method is applied to assign link weights of every two Kansei adjectives as values of cells when constructing an NDSM. Genetic algorithms are used to cluster the Kansei NDSM and find optimum clusters. Furthermore, the process of the proposed method is presented. The details of the proposed approach are illustrated using an example of electronic scooter for Kansei needs clustering. The case study reveals that the proposed method is promising for clustering Kansei needs adjectives in product emotional design.