Experimental study of wind tunnel performance by a two-component laserDopplerAnemometer

Background and Aims: This survey studies the wind tunnel performance by a two- componentlaser Doppler Anemometer, so some experiments were carried out to assess the performance of awind tunnel.Method: The tunnel was capable to produce air velocity of up to 40 m/s.. Measurements ofvelocity profiles have been made actors the test section of wind tunnel through the using a twocomponentfiber optic Laser Doppler anemometer. Measurements of velocity profiles andturbulence intensities have been made across the test section of the wind tunnel using a twocomponentfiber optic Laser Doppler anemometer (I.D.A) for wind speeds ranging from 1 to3m/s.Results: Performance rests of velocity profiles at a given flow rate and various position of aerosolgenerator showed that although uniformity of flow dependent to the place of an atomizer (asaerosol generator) but the variation of wind speed across the test section meets the wind speedrequirements, as specified by US EPAfor 3m/s only.Conclusion:At time which particles velocity reach to less than one micron, the air velocity relateson the similarity of particles an

ROAD TRAFFIC NOISE IN DOWNTOWN AREA OF TEHRAN

Noise pollution is a major problem for the quality of life in urban areas. The present study was conducted to determine the noise levels of road traffic at central area of Tehran. It focused on one of the busy and crowded square along with its 7 connecting streets, which had a heavy traffic and located in the downtown of the city. Total of 115 measuring points were selected along the roads, pavements and in the shopping areas to adequately represent the different acoustically commercial situations. The measuring points were divided in to 4 site-groups namely; Street, Pavement, Shop and Barrier each with 60, 40, 10, and 5 measuring points respectively. The measurements were carried out during a full week days started on Saturday morning and end on Friday evening. The A-weighted continuous equivalent sound level values, LAeq; LA max; LA min ; and the statistical levels: L1, L10, L50, L90 and L99 as well as the octave band center frequencies sound pressure levels were manually measured at each point separately. The mean values of LAeq for Street, Pavement, Shop and Barrier site groups were 78.5, 73.3, 68.7 and 70.8 dBA respectively and the overall mean of LAeq was 74.7 dBA. The statistical test (p<0.01) showed that the mean values for LAeq in all site groups as well as the overall mean value were higher than 65 dBA, which is the daytime governmentally prescribed noise limit for commercial areas. Comparing the individual measurements has also shown the 86.6% exceeded values from 65 dBA. The highest mean noise level in center frequencies upper than 1000 Hz was 71.5 dBA which was observed in the Street site group and the lowest one was 43.2 dBA in the Shop site group at 8000Hz center frequency. The corresponding values for the center frequencies lower than 1000 Hz were 78.2 and 66.1dBA at 63 and 500 Hz which were also observed in the Street and Shop site groups respectively. It can be concluded that the downtown of the city is environmentally noise polluted and the road traffic is the major source of it. Noting the noise emission standards, police control, and promoting the citizens awareness about the high level noise risk may help to relieve the noise problems in the city

Heat Exposure Assessment in the Working Environment of a Glass Manufacturing Unit

Heat stress is a common health problem throughout industry. Any heat stress evaluation requires some exposure assessment of climatic conditions, especially air temperature, humidity, and speed, along with the average temperature of the solid surroundings. In this paper workplace environmental climatic parameters were measured and then evaluated by Wet Bulb Globe Temperature, Corrected Effective Temperature, Heat Stress Index, and Allowable Exposure Time indices among 40 workers in a glass manufacturing unit in Tehran. Also, the effect of available heat control devices on heat stress indices was investigated. The results of this study showed that the obtained heat stress index in individual section and press units is exceeded from 100 (in individual section unit: 302.6, in press unit: 283.6). Also, it is found that the mean average of allowable exposure time in individual section and press units were 13.15 and 12.26 minutes exposure for one hour, respectively. No significant relationship was found between environmental parameters in three parts of body regions (height of head, abdomen and ankle) except for measured air velocity in both units (P<0.007). Positive correlation was found between wet bulb globe temperature, corrected effective temperature and heat stress index indices, but negative correlation was found between allowable exposure time and other indices. Mann Whitney non-parametric test revealed significant relationships in wet bulb globe temperature, corrected effective temperature, heat stress index and allowable exposure time indices when metallic shield was used as heat absorber

"EVALUATION OF MUSCULOSKELETAL DISORDERS RISK FACTORS AMONG THE CREW OF THE IRANIAN PORTS AND SHIPPING ORGANIZATION’S VESSELS"

Musculoskeletal disorders (MSDs) are important causes of work incapacity and loss of work days. MSDs are major problems in almost all countries and increasingly can be found in service industries such as maritime sector. This study aimed at evaluation of MSDs symptoms among crew of tugboats, dredgers, pilot boats and barges by using Nordic Musculoskeletal Questionnaire (NMQ) and also determination of work-related MSDs risk factors by application of Ovako Working Analysis Posture System (OWAS). The result showed that 28.4% of body postures rated in action category 3 and 4 of OWAS. It seems that OWAS cannot be used as a determination method of risk factors for all jobs. Also, the best and sometimes the only way to correct awkward postures is correction of worker&apos;s back position