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Showing 4 results for Mohammadbeigi
Validation of air enthalpy in evaluation of heat stress using wet bulb globe temperature (WBGT) and body core temperature: A case study in a hot and dry climate
Hamidreza Heidari, Hoda Rahimifard, Abolfazl Mohammadbeigi, Farideh Golbabaei, Robabeh Sahranavard, Zahra Shokri,
Volume 8, Issue 1 (4-2018)
Abstract

Introduction: Considering the necessity of evaluating novel thermal indices for different individual and environmental conditions, the aim of this study was validation of a new enthalpy index for evaluation of heat stress in hot and dry climate.


Material and Method: In this descriptive analytical 97 city services outdoor workers were randomly selected and evaluated in spring and summer seasons in Qom city, Iran. Correlation between new enthalpy index and standard WBGT index, as well as physiological response of deep body temperature was studied and analyzed.


Result: Findings showed that regardless of the time of measurements, correlation between enthalpy and WBGT index was better than its correlation with tympanic temperature (R2= 0.756 versus R2= 0.391). Considering the time of measurement, it was found that with increasing temperature and decreasing humidity, the correlation between indices was reduced, although the correlation ratio was maintained similar.


Conclusion: Due to the simplicity of the enthalpy index measurement ,its independency to measure the globe temperature and the possibility of estimation of this index using daily climate parameters in meteorological stations, and on the other hand, appropriate validity of enthalpy against WBGT and core temperature, it can be a good alternative for WBGT index and as a screening index for thermal environments in hot and dry condition.


Comprehensive causal analysis of occupational accidents’ severity in the chemical industries; A field study based on feature selection and multiple linear regression techniques
Ahmad Soltanzadeh, Hamidreza Heidari, Heidar Mohammad, Abolfazl Mohammadbeigi, Vali Sarsangi, Milad Darakhshan Jazari,
Volume 9, Issue 4 (12-2019)
Abstract
Introduction: The causal analysis of occupational accidents’ severity in the chemical industries may improve safety design programs in these industries. This comprehensive study was implemented to analyze the factors affecting occupational accidents’ severity in the chemical industries.
Methods and Materials: An analytical study was conducted in 22 chemical industries during 2016-2017. The study data included 41 independent factors and 872 accidents in a ten-year period (2006-2015) as a dependent variable. Feature selection algorithm and multiplied linear regression techniques were used to analyze this study.
Results: Accident severity rate mean was calculated 214.63 ± 145.12. The results of feature selection showed that 30 factors had high impacts on the severity of accidents. In addition, based on regression analysis, the severity of accidents in the chemical industries was affected by 22 individuals, organizational, HSE training, risk management, unsafe conditions and unsafe acts, as well as accident types (p<0.05).
Conclusion: The findings of this study confirmed that accidents’ severity in the chemical industry followed the multi-factorial theory. In addition, the main finding of this study indicated that the combination of features selection algorithm and multiple linear regression methods can be useful and applicable for comprehensive analysis of accidents and other HSE data.

Investigation of the compatibility of wet bulb globe temperature (WBGT) and predicted heat strain (PHS) in assessing the environmental conditions and heat load imposed on individuals: a case study in bakery workers
Vahid Gharibi, Abolfazl Mohammadbeigi, Mahdi Asadi- Ghalhari, Hamidreza Heidari,
Volume 10, Issue 1 (3-2020)
Abstract
Introduction: This study was designed with the main purpose of examining the compatibility of the two indicators of wet bulb globe temperature (WBGT) and predicted thermal strain (PHS) in assessing the environmental conditions and the heat load imposed on the subjects.
Method: In this cross-sectional study, 163 bakers were included in the study. Thermal stress was determined using the WBGT and PHS. At the same time, physiological responses of subjects were recorded, including tympanic temperature, heart rate and mean skin temperature. Finally, the predicted heat strain was evaluated and compared with actual values.
Results: Based on the results, the WBGT index is accompanied with an underestimation and PHS with  an overestimation, compared to the tympanic temperature. In addition, the WBGT index with the core temperature and the predicted rectal temperature component of the PHS index are the most consistent (kappa value of 0.614 and 0.66, respectively). While the Kappa value is between the amount of water lost and the WBGT index, it indicates a mismatch (Kappa = 0.339).
Conclusion: The prediction of heat strains only based on the PHS index cannot reflect the actual heat load on individuals in thermal environments such as bakeries and it is associated with an overestimation. On the other words, this indicator is more suitable for indoor thermal environments, with minimal variation in individual and environmental factors affecting thermal stress
Analysis of the safety effectiveness of methane gas valve pits: A Case Study in the Steel Industry Based on Hazardous Areas Classification
Ali Fardi, Mohammad Karkhaneh, Hamidreza Heidari, Abolfazl Mohammadbeigi, Ahmad Soltanzadeh,
Volume 12, Issue 2 (6-2022)
Abstract
Introduction: Methane is one of the most widely used gases in industries with a high flammability potential. This study aimed to evaluate the efficiency of ventilation systems installed on methane valve pits based on hazardous areas classification.
Material and Methods: This study was implemented in a steel industry in Qom Province in 2019. The tools used in this study were a DELTA OHM pitot tube (DO-2003) to measure wind speed, EPA Protocol for equipment leak emission estimates (U.S. Environmental Protection Agency) and IEC-60079-10 for evaluating the safety of ventilation of methane valve pits.
Results: The methane LELm was about 0.0334 kg/m3, and the volume of the release area was approximately VZ = 0.053 m3. The expected leak emissions were within the Vz < 0.1 m3 range. The ventilation system embedded on methane distribution pipelines was not effective for openings with diameters of more than 0.3 mm and the volume of gas inside the valve pits would quickly exceed high ventilation border which might lead to a dangerous accumulation of gas in the valve pits.
Conclusion: Given that a very small opening or leak in gas transmission valves may lead to the formation of an explosive atmosphere, it is essential to monitor methane before entering the valve pit area and performing any operations on valve pits.
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