Mohammad Muzammil

Physiological effect of vibrations on tractor drivers under variable ploughing conditions.

Physiological Effect of Vibrations on Tractor Drivers under Variable Ploughing Conditions: Mohammad Muzammil, et al. Department of Mechanical Engineering, Ergonomics Laboratory, Faculty of Engineering & Technology, Aligarh Muslim University, India—The vibration conditions to which tractor operators are subjected are complex and varied with multi axis translation and rotational vibration inputs to different parts of the body. Working under such conditions may lead to human fatigue and other driving related hazards. The present research was carried out to study the operators under varying conditions of vibration while driving a tractor with and without farm equipment on different fields. Test runs were conducted in wet and dry fields to determine the levels of vibration generated at different engine speeds. On the basis of this study three levels of vibration namely 2.5, 3.5 and 5.0 m/s2 were selected. Five subjects, all males, with no experience in the field of tractor driving participated in the study. The data were analyzed on the basis of three factor repeated measure kind of experimental design. The results showed that the main effects of farm equipment and the vibration level were statistically significant but the effect of field type was found to be statistically non‐significant. The results of the study call upon the ergonomists to design and develop a tractor where the driver may be relieved of vibration induced stresses. Front loading of farm equipment is recommended for improved visibility and better working posture.

Human Performance under the Impact of Continuous and Intermittent Noise in a Manual Machining Task

Experimental research was conducted to determine the performance of operators while carrying out industrial tasks in the presence of continuous and intermittent noise. Experimental investigations were carried out at 90, 95, 100 and 105 dB (A) for both types of noise. Two groups of subjects, one having a working experience of 2-7 years and other with 7-12 years were selected for the two studies. The number of units produced was taken as the measure of human performance. The results of the study showed that the level of noise and working experience were statistically significant when the task was carried out in a continuous noise environment. While under intermittent noise conditions effects of noise and work experience and the interaction effect of noise and work experience were all observed to be statistically significant. Investigations also revealed that intermittent noise had a more detrimental effect on performance when compared with continuous noise.

Design of a workstation and its evaluation under the influence of noise and illumination for an assembly task

OBJECTIVE An experimental research was conducted to design a workstation for a lock manufacturing assembly. PARTICIPANTS Two experiments were conducted in the present study. Nine male subjects in the age range of 18-35 years participated in the first experiment. For the second experiment, nine subjects in each of the three age groups (viz. 17-22, 23-28 and 29-35 years) volunteered for experimental investigations. METHOD The designed workstation was evaluated under varying levels of noise and illumination for workers of different age groups. Three different workstations were evaluated. The task was performed by a worker in two different sitting positions and three settings of arms position. RESULTS It was found that workstation type, backrest support and arms positions were all having a statistically significant effect on task performance. Workstation with work surface to seat height ratio of 1.82 was found to be better when the task was performed using backrest and arms were supported on the work surface. This workstation was evaluated for three different age groups of workers under different levels of noise and illumination. The results of the study showed that age of the worker, illumination level and level of noise were all contributing significantly towards task performance. CONCLUSIONS The design of a workstation for assembly task would help greatly in creating a better working environment and enhancing the productivity of workers exposed to environmental stressors like noise and illumination.

Effect of illumination, noise and text/background colour on spontaneous eye blink rate

This study investigated the effect of varying levels of illumination, noise and colour combination on blink rate for subjects of different age groups (21–30, 31–40 and 41–50 years) having Internet exposure duration of less than 2 h/day (category 1) and more than 2 h/day (category 2). The pseudo reading task was designed as a software program to investigate the reading task performance. Results showed that the text–background colour combination was significant on the change in spontaneous eye blink rate (SEBR) values on both categories of users for age groups of 21–30 and 41–50 years. The effects of illumination and noise were not significant for subjects of all categories and age levels except for age group of 31–40 years with Internet exposure duration of more than 2 h/day, where illumination was observed to be significant. The results of the study further showed that ambient illumination did not affect significantly the SEBR values for every age group investigated in this research.

Effects of vibration push force, exposure duration and working posture on operators performing a grinding task

It has been shown that vibration level, push force, exposure duration and working posture cause unfavorable effects on the work performance when hand held vibrating tools are used by operators. The present study analyzed the effects of these variables on the heart rate and systolic blood pressure of the operators carrying out a manual-grinding task. Four levels of vibration (12.5, 13.6, 14.8 and 18 m/s 2 ), three levels of push force (5, 10, 15 N), three levels of working posture (180 ◦ , 150 ◦ and 120 ◦ elbow flexion) and three exposure durations of 3, 5 and 7 min were selected for the study. Thirty male subjects with no prior experience in the field of grinding participated in the study. Results indicated that in the kind of task undertaken, the main effect of equivalent level of vibration, exposure duration, push force and working posture were all statistically significant. Also an increase in the change in blood pressure and heart rate values were observed with the increase in exposure duration and push force. When the task was performed with flexion angle of 120 ◦ , change in heart rate and blood pressure values was minimum when compared with the other two working postures. Relevance to industry: Workers using various hand held tools are prone to injuries. Present research may help greatly in reducing task related injuries and enhance performance.

Vibration effects on cognitive task performance in a rural road automobile driving environment

Research has been carried out to investigate the effect of left or right handedness on cognitive performance under the impact of vibration in a rural road-driving environment. Fourteen subjects (7 right handed and 7 left-handed), all males, participated in the study. The independent variables selected were handedness, difficulty index and equivalent level of vibration. The reaction time was measured in ms. The data collected was analysed using 3 factors ANOVA. Results of the present research showed that handedness and the level of equivalent vibration were statistically non-significant while the difficulty index was found to have a significant effect in the driving environment undertaken in the study. The interaction between handedness and difficulty index was also observed to be statistically significant. However, the interaction between vibration level & difficulty index and handedness & vibration level were statistically non-significant. The second order interaction i.e. handedness x vibration level x difficulty index also emerged to be non-significant

Bagasse—A Replacement of Glass Wool as an Acoustic Material

Present study was conducted to investigate and suggest a non-traditional material, in place of glass wool, which may be environmental friendly (green material) and may not harm the worker while performing the task. Bagasse, a green fibrous byproduct, obtained from the sugarcane stalks, was selected for study. The surface grinder (Make: Alex machine tool, Model No. H 208) selected in the present research generated a level of equivalent noise (Leq) in the range of 66.7–70.3 dBA. Two enclosures were designed for covering the grinder wheel and the working table with a 4 mm ply for bagasse fibers and glass wool which were spread in the annular space provided inside the enclosure and were put in place using steel wire mesh. The thickness of the fibrous layer of both the materials was taken to be 20 mm. The level of noise obtained using bagasse was 61.0 dBA while for fiber glass wool it was 64.3 dBA. The results of the study showed that there was a decrease of 6.6 dBA when bagasse was used as a noise-reducing material while a decrease of 3.3 dBA was obtained using glass wool.