فهرست مطالب morteza parsa

The present study investigated the effect of noise on blood pressure and heart rate of workers in an oil and gas industry in Khuzestan province.

This descriptive-analytical study was conducted on 60 employees of one of the oil and gas industries who worked in administrative, warehouses, and operation units. A demographic questionnaire, a Beurer blood pressure monitor (BC16), and a sound level meter (TES1358) were used for data collection. Blood pressure and heart rate were measured before, during, and after the work. ANOVA and Paired Sample Test were used for data analysis in SPSS software.

Occupational exposure of administrative, warehouse, and operation unit workers to noise were 50-60, 85-75 and 95-85 dBA, and their heart rate was 79.38, 82.12, and 85.73 beats per minute (BPM), respectively. Before exposure to noise the mean heart rate of workers in the operation unit was 82.29±3.58 BPM and after exposure it was 85.73±1.92 BPM, and the difference was statistically significant (P-Value<0.001). The mean blood pressure of exposed to noise workers was significantly higher than that of non-exposed to noise workers (P-Value<0.001). The heart rate of operation unit workers was significantly higher, compared to other studied workers (P-Value<0.001).

Considering the effect of noise on blood pressure and heart rate and the direct relationship between these parameters and cardiovascular diseases, it can be claimed that noise is one of the risk factors of cardiovascular diseases.

Gears are widely used to transmit power between two parallel shafts. Study on the lubricant film which is formed between the engaged teeth of pinion and gear is of high importance in predicting the performance of the power transmission system as well as surface failure and wear. Gear surfaces in comparison to rolling element bearings have a higher surface roughness and thus considering the surface roughness is important in gear analysis. In this research، the performance of a pinion-gear system operating under mixed-elastohydrodynamic lubrication is being investigated using load-sharing concept. The contacting asperities might experience elastic، elasto-plastic or fully plastic contact. The engagement of pinion and gear for each point along the line of action is replaced with contact of two cylinders. The radii of these cylinders as well as the exerted load vary along the line of action. Using load-sharing concept، the proposed model can predict the lubricant film thickness، friction coefficient، and portion of the total load that is carried by asperities as well as lubricant film. The predicted results are verified by comparison to other available methods which are published in the literature.