[Assessment of hazard kiln cement factory with failure mode effects and criticality analysis [FMECA]]

Technique of Failure Modes Effects and Criticality Analysis, FMECA, is a method for identifying and analyzing all potential failure modes of a system.This technique is used to prevent failures and to reduce their effects on the system. The main goal of this study was identifying and analyzing of the potential failure modes and assessing the effects of failures in the cement kiln by FMECA method. First the boundaries of the system were determined and then system was divided into its components [systems and subsystems] at a specified level with respect to the analysis goals. Then, effects of failures on production and system were appointed and causes and severity of failures were determined. Finally the results were recorded in FMECA appropriate worksheet. Meanwhile failure priority was presented. Totally one hundered failures were identified. While the highest risk priority number was related to body warping with RPN = 270, the lowest risk priority numbers [RPN=15] were associated to lacking of air supply by fan and unproperly acting of the main brake of kiln. The maximum frequency of failures was found in the kiln body. This study indicated that one failure may lead to other defects in various components of the system itself. Therefore, the implementation of a documentation system to record defects was emphasized in order to improve the machinery safety level. Furthermore, it can be concluded that a planned preventive maintenance could effectively decrease the probability of failures and number of defects consequently.

[Determination of aerosol emission and bag filter efficiency in fire-proof products industries]

Today, the environmental pollution caused by fire-proof break producing factories is one of the critical and challenging issues in our country. Aerosols emission concentration of the factory stacks and determining of bag filters efficiency were aims of this study. In this research, the concentration of emitting dust from 6 stacks related to Kaolin preparation, Calcinatory, Shamout, Specific mass, Extrude Furnace and Shuttle Furnace units were measured during 2006-2008. Also, the efficiency of bag filters of Kaolin preparation, Calcinatory, Shamout, Specific mass units were determined in 2008. Devices M9096 Particulate Sampling Train and DURAG model [D-RC 80] were used in this research. The rates of dust concentrations in years 2006-9 in Kaolin unit were; 284, 112 and 12.5 mg/m3, in Shamout unit were; 120, 140 and 73 mg/m3, in Calcinatory were; 178, 179 and 173 mg/m3, Specific Mass were; 291, 283 and 60 mg/m3, in Shuttle Furnace were; 14.7, 14.3 and 14.8 and in Extrude Furnace were; 12.6, 13.7 and 12.7 mg/ m[3]. Efficiency of bag filters was 99.896% for Kaolin unit, 06.499% for Shamout unit, 92.348% for Calcinatory and 99.782% for Specific Mass unit. During 2006 and 2007 the rate of dust emission in Kaolin preparation, Calcinatory and specific mass have exceeded than the national emission standard but in 2008, the rate of dust emission from Kaolin Preparation and Specific Mass units were extensively reduced to the lower than national emission standard limit due to proper maintenance and replacing of damaged parts in time. Efficiency of bag filters has been ideal in Kaolin unit and Specific Mass unit but it was low in Shamout and Calcinatory units

[ impact of low frequency noise on mental performance during math calculations]

The influences of Low Frequency Noise [LFN] on mental performance have been the objectives of many papers in recent years. Many researchers believe that the LFN even at low pressure levels has impacts on mental performance. In the present work the influences of LFN and Reference Noise [RN] at two different sound pressure levels [45 and 65 dBA] on mental performances of college students during solving math problems were studied. Other factors such as annoyance and sensitivity to LFN and hearing status of the participants were also determined. Low Frequency and Reference Noise were generated and verified using cool Edit software program. The number of participants was calculated using data gathered from a pilot study conducted in advance. The mental performance of the students was evaluated while they were exposed to LFN and RN at 45 and 65 dBA sound pressure levels. For this purpose, standard psychological tests were applied. Standard measuring instrumentation including sound level meters, psychological tests, acoustic room and etc were calibrated prior to their application based on standard methods. The results revealed that, Low frequency noise annoyance and sensitivity have no significant differences between different studied ages and sexes. The result also revealed that, a significant correlations exists between sensitivity to low frequency noise and deep mental process [r=0.33, p=0.01]. It was recognized that low frequency nose at 65 dBA can decrease accuracy [p=0.005] and performance [p=0.001] in comparison with reference noise at the same level. Low frequency noise, have impact on mental performance during performing math calculations

Assessment of noise induced psychological stresses on printery workers

The purpose of this study was to assess the relationship between psychological stresses and noise stresses on printery workers in Tehran, Iran. Hence, 267 workers were randomly selected. The Leq and Lmax were measured and the psychological stresses such as depression, anxiety, aggression and job satisfaction were also studied by the relevant questionnaires. The data were statistically analyzed by Pearson correlation test. The results demonstrated that there was no significant statistical relationship between noise and psychological stresses. In addition, by using Spearman regression method, the influence of variables such as age, gender and job history on psychological stresses caused by Leq and Lmax was studied and the results only revealed that the aggression caused by Leq increased in young personnel [P=0.02] as well as, anxiety caused by Lmax increased accompanied by increasing the job history and age of the workers [P=0.002 and P=0.007]. Therefore, more variables must be taken into consideration to judge about noise induced psychological stresses in workplaces

Factors affecting road traffic noise annoyance among white-collar employees working in Tehran

The effect of personal and attitudinal factors, noise level, hearing status and psychological traits on traffic-related noise annoyance among white-collar employees working in Tehran has been carefully analyzed. This survey has been conducted by interviewing 495 citizens working in non-manufacturing industries in Tehran, using questionnaires, Weinstein noise sensitivity scale, Beck's depression, Buss and perry's aggression, Zung's anxiety, job satisfaction and Eysenc's personality inventory. These citizens were office workers or store employees. Noise annoyance was determined both by numerical-based questionnaire criterion and by verbal index. Personal information, attitudinal factors and hearing conditions were determined using a general questionnaire. The amount of workplace noise the participants were exposed to was directly measured at their workplaces. It was revealed that among personal factors, age [p=0.030], marital status [p=0.004], residential period [p=0.001] and wealth [p=0.04] were related to noise annoyance. Attitudinal factors including sensitivity to noise [p=0.001], individual's opinion on the need to control the noise [p=0.000] and individuals' assessment of the amount of the workplace ambient noise [p= 0.000] were found to have relationship with noise annoyance. No meaningful relationship was seen between the equivalent noise level [p=0.879] and statistical noise level of L90 [p=0.909]. The present study revealed that among all effective factors involved in noise annoyance, attitudinal factors had the most significant role in this regard

[Evaluation of noise pollution in crowded areas in Yasuj in 2006]

Human exposure to environmental noise increases day to day and noise is currently a very important stressful factor. One of the common sources of noise is transportation vehicles. Undesirable impacts of traffic persuaded governments to set rules for the problem and when civil planners and road engineers decide to construct highways, they must be sure that the related standards and rules have been met. The aim of this study was to evaluate the rate of noise pollution in crowded areas of Yasuj. Noise measuring was done by using B and K Sound Level Meter [model 2230]. Noise descriptors [Leq, Max, Min] were measured for 10 minutes of any hour during daytime and night in selected areas [11 stations]. One station was also selected as reference point and noise measurement was carried out for the whole week in this station. Leq was found to be 72 +/- 4.4 dB [Max] and 65.4 +/- 7 dB [Min]. Recorded maximum and minimum noise was 99.7 dB [at 17-18 o'clock] and 34 dB [at 4-5 o'clock], respectively. Comparing the findings of this study with standard scales indicates that Yasuj is experiencing high noise pollution

[ influences of low frequency noise on mental performance]

Although the evolution of industrial systems toward digital technologies decreased the exposure to high levels of noise, it has created some problems encountered with low level and provoking noise [low frequency noise]. In the present work, the mental performance of students exposed to low frequency and reference noises at low and high levels [45 and 65 dB] were studied. Additionally, other factors such as annoyance, sensitivity to low frequency noise and hearing status of participants were considered. After generating low frequency and reference noises required for the study, a pilot study was conducted. Then, 54 students participated in the main study after preliminary tests. Their mental performances were evaluated with standard psychological tests while they were exposed to low frequency and reference noises at 45 and 65 dBA. The results showed that noise annoyance and low frequency noise sensitivity do not have a significant correlation with age and sex. The results also revealed that, low frequency noise at 65 dB can decrease concentration [P=0.003] and increase response time [P=0.039] of performance in comparison with low frequency noise at 45 dB. On the other hand, reference noise at 65 dB can increase speed [P<0.001] of performance in comparison with reference noise at 45 dB. Low frequency noise can reduce the mental performance and increase its response time

[Assessment of the effect of occupational noise on workers hearing in small scale industries in Tehran]

Background: in the last decades one of the effective adverse agents on workers health has been workplaces noise. This adverse agent exsit in Small Scale Industries and threatened workers health in this areas. because of increasing small scale industries and workers in our country, this study performed with subject "Determining the effect of noise on workers hearing in small scale industries"

Materials and Methods: in this study 109 workers, between Small Scale Industries workers selected for case group and the same for control group. First workers information was gathered with questionnaire and clinical periodic examinations, and then audiometeric test implemented. Noise indices measurement performed in the workers with sound level meter [CEL-440/480] with ISO 9612:1997[E] Standards. Also octave - band frequency analyses carry out for case group workers in the workstations

Results: results indicated that, mean and standard deviation of Equivalent sound pressure level [LAeqT] for case workers was 94.2+/-6.72 dBA and for control workers 84.87+/-3.97 dBA. In the case group the mean hearing threshold at 4K hz [31.07dB] was less than mean hearing threshold at 8K hz [35.59 dB]. Multiple regression analyses indicated that exposure to noise was the primary, age and precedent the secondary predictor of hearing loss

Conclusion: in this study, pierson correlation coefficient between age and hearing loss and also between work duration and hearing loss was taken. In this conditions, we can expect progression of hearing loss with increase in work duration for occupied workers

Reliability analysis of traffic noise estimation in highways of Tehran by Monte Carlo simulation method

This study was aimed to examine the reliability of traffic noise estimate and measurement techniques in highways of Tehran, capital of Iran. The multiple regressions showed that the traffic flow and the distance from the effective source position are the most important factors to estimate the L10 [1h]. Traffic flow, traffic composition in terms of heavy vehicles and traffic speed are identified as the key factors influencing the generation of traffic noise. The new equations for estimating the noise descriptor L10 was calibrated on the basis of noise measurements. The effects of the key factors on L10 [1h] were examined by the sensitivity analysis and it was found that traffic flow, distance from the effective source position, traffic composition and traffic speed had the most sensitivity on traffic noise, respectively. The probability distribution for each of the key factors was derived with the use of the survey data. The reliability of the traffic noise estimates was obtained from the combined probability distribution of the key factors by Monte Carlo simulation method. This study showed that there was no significant difference between estimated noise by calibrated CoRTN calculation of road traffic noise and measured noise level. The reliability analysis gives the traffic noise estimates with a particular probability or vice versa