Qianxiang Zhou

Electroencephalogram assessment of mental fatigue in visual search.

Mental fatigue is considered to be a contributing factor responsible for numerous road accidents and various medical conditions and the efficiency and performance could be impaired during fatigue. Hence, determining how to evaluate mental fatigue is very important. In the present study, ten subjects performed a long-term visual search task with electroencephalogram recorded, and self-assessment and reaction time (RT) were combined to verify if mental fatigue had been induced and were also used as confirmatory tests for the proposed measures. The changes in relative energy in four wavebands (δ,θ,α, and β), four ratio formulas [(α+θ)/β,α/β,(α+θ)/(α+β), and θ/β], and Shannons entropy (SE) were compared and analyzed between the beginning and end of the task. The results showed that a significant increase occurred in alpha activity in the frontal, central, posterior temporal, parietal, and occipital lobes, and a dip occurred in the beta activity in the pre-frontal, inferior frontal, posterior temporal, and occipital lobes. The ratio formulas clearly increased in all of these brain regions except the temporal region, where only α/β changed obviously after finishing the 60-min visual search task. SE significantly increased in the posterior temporal, parietal, and occipital lobes. These results demonstrate some potential indicators for mental fatigue detection and evaluation, which can be applied in the future development of countermeasures to fatigue.

Measurement and Analysis of Anthropometric Parameters of Young Male Vehicle Drivers

In this study, anthropometric data of 1243 vehicle drivers were sampled and the their age was from 17 to 34 years and averaged 21.85±2.82years. 76 anthropometric static parameters and 11 functional parameters were studied. The 76 static parameters were measured with the Non-contact 3d human boy scanners of VITUS SMART XXL systems while the 11 functional parameters were measured manually with Martin measuring scale. The correlation and fitting formulas of body height, sitting height and other parameters were measured and obtained. We also contrasted measured data with data form GJB 1835-1993. The present analysis showed that the correlation between sizes of body length and sitting height was significant. Sizes of body length and enclosing size and width direction were all increased compared to those in the 1980s. The present results were consistent with other researchers’ current research results. The measured data could be an important basis for the data of young male anthropometric parameters and edition of relative standard and design of specific equipment.

The Experiment Research of Pupil Change for the Evaluation of Mental Workload

To investigate whether the motivation or interesting can take effect on the change of pupil size and whether pupil size reflect mental workload differences in a situation with different task difficulties. Twelve subjects participated in the experiment and they were asked to make target search task of three different difficulty level. The task difficulty levels were controlled through searching different number of differences between pictures. The experiment was done in two different conditions: the subject did the searching task only with basic rewards without time limited; the subjects received different additional rewards according their performance. The pupil size was recorded with eye movement tracking system. The results of the pupil size change showed the common characteristic and also difference for all the subjects. The same characteristic of pupil size change for all subjects was that the pupil size was larger in the second experiment condition than of the first corresponding condition. The difference were reflected on that some subjects pupil size first dilated and then constricted, and some first constricted and then dilated, while some others continuously constricted. Conclusions can be made from the results: the increasing of task difficulty will make pupil dilate, the positive motivation or interesting also dilate the pupil size, while the visual fatigue constrict the pupil size.

The Research of Eye Movement Behavior of Expert and Novice in Flight Simulation of Landing

The objective of this research is to study the eye movement patterns of pilots in landing process by analyzing and comparing the eye movement data of experts and novices so as to reveal their cognitive process of information processing in the final landing stage. Ten experts who have flown above 1000 h and fourteen novices whose flight hours were between 200 to 400 participated the experiment. All subjects’ task was to implement a landing task according visual flight rules in no wind and shinning day and the landing task was completed with a high fidelity flight simulator. Eye movement data and flight parameters data were recorded during the experiment. The result showed that there was obvious difference of flight performance between experts and novices. The course deviation, roll angel and pitch angel of experts were better compared to that of novices. And the land course of experts was also better than that of novices. It could be found by the comparison of eye movement index between experts and novices that there were obvious differences of six eye movement index. Expert showed shorter fixation time, smaller pupil size changes, lager scanning range, faster scan velocity, greater scan frequency and greater fixation frequency. So the conclusion can be made that there is obvious differences between experts and novices not only in flight performance but also in eye movement pattern; the scanning pattern is related to flight performance and effective scanning pattern is related to better flight performance; so the measurement of eye movement pattern can be used to evaluate and forecast flight performance and thus to guide the training.

Evaluation of the Crew Workload to Quantify Typical Mission Profile Special Vehicles

In the special vehicle research, the crew workload quantitative assessment may be a human-vehicle system function rationally allocated, the occupants optimal design tasks provide important reference. In this paper, base on special vehicles semi-physical simulation simulator test environment, explores the impact of breakthrough deep attack workloads quantitative assessment method of two typical mission profiles. The study innovative uses of cognitive attention measuring device measured the crew workload, to decompose mission profile, cognitive channel subjective evaluation questionnaires, and task performance and subjective evaluation of the results of the analysis. The research methods and conclusions made by the crew used workloads the quantitative evaluation system provide an important reference.

Optimizing the physical ergonomics indices for the use of partial pressure suits

This study developed an ergonomic evaluation system for the design of high-altitude partial pressure suits (PPSs). A total of twenty-one Chinese males participated in the experiment which tested three types of ergonomics indices (manipulative mission, operational reach and operational strength) were studied using a three-dimensional video-based motion capture system, a target-pointing board, a hand dynamometer, and a step-tread apparatus. In total, 36 ergonomics indices were evaluated and optimized using regression and fitting analysis. Some indices that were found to be linearly related and redundant were removed from the study. An optimal ergonomics index system was established that can be used to conveniently and quickly evaluate the performance of different pressurized/non-pressurized suit designs. The resulting ergonomics index system will provide a theoretical basis and practical guidance for mission planners, suit designers and engineers to design equipment for human use, and to aid in assessing partial pressure suits.

Based on Upper Extremity Comfort ROM of Ergonomic Methods for Household Products Design

The structure of product demands a higher level of user performance and involves risk that may possibly negatively impact the user’s safety and health. For this reason, the evaluation or design of new products requires extensive knowledge of human interaction, including the operation and comfort of motion. This paper presents a technique for assessment of the upper extremity comfortable ROM. The method is based on new experimental data from perceived discomfort of subjects, and uses digital human modeling (DHM) systems to verify the perceived discomfort rank. 55 participants participated in this experiment. They were required to extract and insert pegs from different panels. We get the comfort ROM of subjects according to subjective comfortable ratings and use digital DHM systems to verify the perceived discomfort rank. In this paper, comfortable motion range of the 50th percentile was shown only. Using DHM systems, we can supply upper limb comfortable motion range of different percentile Chinese people for household products ergonomics design.

Assessment of Pilots Mental Fatigue Status with the Eye Movement Features

With the domain of aero technics, aviation mental fatigue research has been aimed at preventing the tragedy caused by fatigue flights. There are specific effects of the mental fatigue on behavioral performance in pilots, characterized as a decrease of reaction rate and distractibility of attention. Fourteen subjects completed an experiment with visual search tasks and simulated flight task. The eye movement data were recorded by the eye tracker with 120 Hz of the sampling rate. The results of the questionnaire showed that the fatigue value in the fatigue periods was higher compared with the awake periods. Moreover, the results of eye movement features showed that the PERCLOS and blinking frequency amplitude increases monotonically with increasing fatigue value during the task. Lastly, the conclusion can be made that the measurement of eye movement pattern can be used to assess and forecast pilots mental fatigue status.

Experimental Research on the Armored Crew’s Depth Perception

To establish the depth perception database of Chinese armored crews and provide base information for the selection and training of the related population. The depth perception data of 565 Chinese young males from seven natural areas were collected. The Participants’ age range from 17 to 32. The data were statistically analyzed and compared with related researches in China and abroad. Within a certain range, the distance between the variance simulation and the standard constant stimulation had no significant effect on the depth description. A significant difference existed among the monocular and binocular. Depth perception in armored crews of different education and living areas did not exhibit significant different. Depth perception of armored crews was better than general population, seamen and drivers. By sampling on a national scale, the depth perception database is established for Chinese armored crews. This study provides the basic data for the training and selection of armored crews and can be also used as reference for cognitive parameters researchers.

Analysis and Modeling of Fatigue During Weight-Bearing Walking

The objective of this study was to discuss the mechanical characteristics and distributed regularity of shoulder, waist and back of the human body through the experiment of weight-bearing walking; to establish the dynamic fatigue model based on stress regularity to provide a reference for the task design of weight-bearing walking and the ergonomics simulation of backpack. Thirteen healthy people participated the experiment that was recruited by internet and they were all men. Every subject made a 21 min weight-bearing walking on the treadmill with the speed of 5 km/h and a 15 kg load. The pressure data of their shoulder, back and waist was collected by pressure measuring system and the feeling of fatigue of the above three body parts of the subjects was asked every 3 min by using Borg scales. The results showed that the force of the subjects’ left shoulder and right shoulder was different and the force was higher on one shoulder while it was lower on another shoulder. The stress regularities of waist and back were similar to the shoulders and it was higher on left side of some subjects while it was higher on right side of other subjects. Also the stress on waist and back was different. The stress on shoulder was much higher than it was on waist and back while the stress on back was the lowest. The impulse was calculated based on the stress data of three body parts. The model was established based that the impulse was as dependent variable and the feeling of subjects’ fatigue was as independent variables. It showed a strong linear relationship between the pressure impulse of the three body parts and the feeling of subjects’ fatigue. The subjects’ fatigue could be well predicted during weight-bearing walking by using the linear model of impulse and subjective fatigue. So the conclusion of this study can be made that the stress on shoulder, back and waist is not asymmetric and it was great difference on the body three parts. The shoulder is not only the main bearing pressure part, but also the easiest part of fatigue. The fatigue can be well predicted during weight-bearing walking by the linear model that combine impulse and the feeling of subjects’ fatigue.