Investigating human error in Iran's copper mines using the CREAM based on human cognitive reliability analysis.

Objectives Human error has been recognized as one of the top causes of most accidents in mines. This study aimed to identify and assess cognitive errors among copper miners using the cognitive reliability and error analysis method (CREAM). Methods. This cross-sectional study was carried out in one of the copper mines in Iran. First, all tasks were analyzed by hierarchical task analysis (HTA). Then cognitive errors were assessed using the CREAM. Results. With respect to the basic CREAM results in the operational units, including extraction, crushing and processing, human error probability (HEP) was obtained as 0.056, 0.0315 and 0.0177, respectively. Based on the results of the extended CREAM, the types of errors identified for all tasks in the three operational units were mainly associated with execution (53.4%), observation (40%), interpretation (5%) and planning (1.6%). Also, the cognitive errors were related to execution, monitoring, observation, communication, diagnosis, recording and planning, respectively. Conclusion. The results showed that human error is very high in the operational units of the mine. Therefore, immediate actions are needed to improve safety performance in the mine units, which determine the role of various factors in human errors and can provide the possibility of implementing more effective interventions.

Evaluation of human error in workers of an Iranian copper mine during the COVID-19 pandemic using the CREAM.

BACKGROUND: The outbreak of COVID-19 has adversely affected both global economy and public health around the world. These effects have also been observed in many workplaces, including mines. OBJECTIVE: This study aimed to examine the human error of copper miners during the pandemic. METHOD: This descriptive-analytical, cross-sectional study was performed on 192 workers of a copper mine in Iran. For this, occupation tasks were firstly analyzed using the Hierarchical Task Analysis (HTA), and then the human error in different subunits was assessed using the basic Cognitive Reliability and Error Analysis Method (CREAM). The prevalence of COVID-19 among miners was determined by assessing positive PCR test records. RESULTS: The probability of human error in the operational subunits including mining, crushing, processing, and support subunits was estimated to be 0.0056, 0.056, 0.0315, and 0.0177, respectively. All three operational units were found to be in the scrambling control mode. The support unit was determined to be in the tactical control mode. Approximately 50% of all workers had been infected with COVID-19, with the highest prevalence in support units. CONCLUSION: The results suggest that during the COVID-19 pandemic, copper miners are at higher risk of human error induced by poor working conditions. Therefore, it is recommended to employ some management strategies such as promotion of safety, health monitoring, and adopting supportive measures to control occupational stresses and therefore the probability of human error in the mine's operational units.

Improving the performance of double-expansion chamber muffler using dielectric beads; optimization using factorial design.

PURPOSE: Noise pollution is a common health hazard worldwide which is emitted along with chemical air pollutants, simultaneously from many sources. Some studies have been conducted to control these pollutants, simultaneously with promising results being achieved. Dielectric beads have been used in air pollution control technologies, successfully and probable effectiveness of them in noise reduction can be promising in dual use of them in the exhausts emitting noise and air pollution, simultaneously. METHODS: In order to investigate the effectiveness of dielectric beads in noise reduction, two types of them; namely glass and ceramic beads, were placed separately inside the connecting tube of a double-expansion chamber muffler. Then the transmission loss (TL) of muffler was examined using impedance tube. A factorial design was used to evaluate and optimize the effect of noise related parameters on TL of such a system. RESULTS: Results show that the presence of dielectric beads has significant effect on TL of muffler. The maximum TL was obtained as 74.76 dB for muffler with ceramic beads, under the optimal condition of 5250 Hz and 120 dB. Measurement of TL and sound absorption coefficient (SAC) of glass and ceramic beads showed that the noise reduction in muffler with ceramic and glass beads is probably due to SAC in ceramic beads and noise reflections in glass beads, respectively. CONCLUSION: These results promise the dual use of dielectric beads in the exhausts emitting noise and air pollution simultaneously.

Energy efficiency improvement in nitric oxide reduction by packed DBD plasma: optimization and modeling using response surface methodology(RSM).

The non-thermal plasma (NTP) is a superior proposed method for nitric oxide removal because of operation at atmospheric pressure and ambient temperature. The energy consumption is the main challenge of using this technology. The packed plasma reactor with dielectric materials has been extensively investigated; it has higher energy efficiency. In this study, the energy efficiency and the other effectiveness factors in nitric oxide removal by NTP reactor packed with ceramic and glass beads optimized and modeled using Response Surface Methodology. The findings showed the maximum energy efficiency was 132.69g/J in the optimal conditions of initial concentration, gas flowrate, and duty cycle(voltage) equal to 1050 ppm, 2.5 L/min, and 9%(22KV), respectively in the packed reactor with ceramic beads by 1.7 times than the empty reactor. It is concluded that the use of ceramic beads as a dielectric material in the discharge space significantly increased energy efficiency in the removal of nitric oxide.

Evaluation of musculoskeletal disorders in sewing machine operators of a shoe manufacturing factory in Iran.

INTRODUCTION: A 15-year research conducted in USA showed that compensation expenses paid to workers for musculoskeletal disorders (MSDs) of back exceeded 128 million Dollars calculated on the basis of 0.97 Dollars per hour of work. In addition, according to the latest studies carried out in relation with disease burdens with risk factors in Iran, DALYs indices for low back pain, knee arthrosis and other musculoskeletal disorders have been reported to be 307772, 291305 and 872633 respectively, which have caused the work related diseases to occupy the second position in the country, after cardiovascular diseases. On the other hand, in accordance with occupational health indices of Iranian health ministry, 37% of all working population had had poor work postures with 15% of all working population had been working with inappropriate working tools in the year 2009. METHODS: This was a case study comparing exposed workers with control group using Standard Nordic Questionnair in sewing machine operators of a shoe manufacturing factory in Iran. In this study, the mentioned questionnaires were filled out for the exposed group (25 sewing machine operators with average age of 43.5 years with work records of 16.8 years) and control group (15 employees from administrative department with average age of 39.8 years with work records of 13.4 years) which both were selected through simple random method. RESULTS: There were statistically significant differences in age between musculoskeletal disorders of right elbow (p = 0.033), thigh (p = 0.044), both knees (p = 0.019) and ankles (p = 0.039). There were also statistically significant association between gender and musculoskeletal disorders of right elbow (p = 0.028), thigh (p = 0.026) both knees (p = 0.011); right shoulder disorders (p = 0.018) and work records; disorders of both knees (p = 0.031) and number of cigarettes smoked. CONCLUSIONS: In general, prevalence of disorders of cervical area, shoulders with hands, vertebral column, back, knees, thigh with feet were higher in exposed group due to poor work posture. Meanwhile, female workers were inflicted more than males. On the other hand, these disorders were seen more with increased work records and age in which, improvement of work postures, training for better execution of tasks and conducting periodic screening tests are being recommended.