Showing 4 results for Eskandari
Asghar Ghahri, Farideh Golbabaei, Leila Vafajoo, Seyed Mohammad Mireskandari, Mehdi Yaseri, Seyed Jamaleddin Shahtaheri, Faranak Najarian,
Volume 8, Issue 2 (6-2018)
Abstract
Introduction: Anesthetic gases used in hospitals include N2O and halogenated hydrocarbons (such as sevoflurane) which can be released through leakages and uncontrolled exhalation by the patient into the ambient air of clinical staff. These gases have greenhouse effect and damage to the ozone layer and serious risks such as reproductive, preterm delivery and fetal abnormalities and increased spontaneous abortion on the health of operating room personnel. Therefore, removal of these gases from the workplaces is essential especially in the treatment centers. The purpose of the present study was to investigate the adsorption of sevoflurane from air by using activated Charcoal and also the effect of acid modification on its performance.
Material and Method: In this study, two adsorbents of unmodified and modified activated charcoal with nitric acid were used to remove sevoflurane. After preparation, the adsorbents were characterized using XRD, FT-IR, BET and FE-SEM methods. After characterization, the breakthrough and adsorption capacity of sevoflurane on both adsorbents were determined using the modified wheeler equation.
Result: The results of characterization showed that acid modification did not affect the crystalline structure of activated charcoal and increased the adsorption and microporous of acid-modified activated charcoal in comparison with unmodified activated charcoal. It also reduces surface functional groups of the activated carbon. The results of determination of adsorption capacity indicated that the adsorption capacity of modified activated charcoal was improved in comparison with unmodified activated charcoal.
Conclusion: The results demonstrated that both adsorbents have the ability to absorb sevoflurane and modified activated charcoal have a better performance in this process. This effect may be due to the surface area of adsorption and volume of micro pores more than the unmodified activated charcoal.
Tahereh Eskandari, Iraj Mohammadfam, Mostafa Mirzaei Aliabadi,
Volume 9, Issue 4 (12-2019)
Abstract
Introduction: The safety of CNG stations is important because of their location in urban areas, as well as to prevent accidents and to protect the safety of personnel, property, and environment. An event occurrence analysis with probability updating is the key to dynamic safety analysis.
Methods and materials: In this study, the Failure Modes and Effects Analysis (FMEA) technique was used to determine the hazards of the study unit, the method of analyzing. After determining the hazards with high risk, the Bayesian fault tree analysis (BFTA) method was used to determine the effective causes of events occurrence and the type of possible relationships among them.
Results: First, the phase of hazards identification, 16 Hazardous equipment were identified. Then the Risk Priority Number for the identified equipment was calculated. The results showed that the dispenser system had the highest risk priority number and was identified as the most critical equipment. According to this, the dispenser gas leakage (as the top event) was selected in this study. Then, the analysis of the dispenser gas leakage, using BFTA method identified 56 main causes, including 17 intermediate events and 39 basic events. Finally, cracking and corrosion of the dispenser hose were determined the most effective factor in the occurrence of the top event. The probability of occurrence of the top event based on FTA and BFTA analysis was calculated 9.67×10-2 and 9.11 × 10-2, respectively.
Conclusion: The result of the study that by employing the Bayesian Network, can create a useful guideline to determine the relationship between the occurrence causes of the top event. This provides an assessment of the effectiveness of preventive measures before using them.
Soleiman Ramezanifar, Ehsan Ramezanifar, Elahe Khadiv, Ali Salehi Sahlabadi, Davoud Eskandari, Mahshid Namdari,
Volume 12, Issue 3 (9-2022)
Abstract
Introduction: Human error can occur in many work environments, especially in control rooms. Due to the vital role of the central railway traffic control room in guiding and controlling all types of trains along the railway network, any error in this control room can lead to a catastrophic accident. This study aims to identify and assess human error in the central control room of railway traffic using the HEART technique.
Material and Methods: This descriptive cross-sectional study was performed in 2021. In this research, tasks and sub-tasks were identified using the hierarchical task analysis (HTA) method. Then, the probability of human error was assessed using the HEART technique.
Results: Based on the results of the HTA method, 67 main tasks, and 149 sub-tasks were identified. The study results on the probability of human error using the HEART technique showed that the three main tasks of the traffic expert (distribution of types of diesel, establishing the freight priority, and planning the movement of trains) had the highest probability of error. In addition, the most critical factors influencing human error were “evidence of illness among employees”, “sleep disorder”, “inexperience”, “unfamiliarity”, and “stress”.
Conclusion: The results of this study indicated that the central railway traffic control room employees are prone to errors, and if these staff make errors, irreparable accidents will occur. To reduce the probability of error of these employees, measures should be considered, such as using regular and appropriate shifts, the use of skilled and competent people, and so on.
Behzad Gholami, Mousa Jabbari, Davood Eskandari,
Volume 14, Issue 2 (6-2024)
Abstract
Introduction: One of the ways to produce electricity in power plants is to use gas turbines and generators. Due to the use of methane gas as the fuel of the burners and the high rotation speed, this equipment has a high DOW index level, therefore, if the hazardous conditions in the gas turbine are not controlled by the safety instrumented system and the process is not directed to a safe state, Catastrophic events will occur such as fire and explosion and damage to property and people as well as interruption of the power generation process will happen in the long term, so gas turbine safety instrumentation systems can be considered as “critical safety systems”. Therefore, the reliability and availability of their function should be evaluated. The purpose of this research is to determine and verify the safety integrity level (SIL) related to the safety instrumented function (SIF) of the gas turbine and generator in a combined cycle power plant.
Material and Methods: In this study, the safety integrity level was determined by using two methods, Calibrated Risk Graph (CRG) and Independent Protection Layer Analysis (LOPA), and to verify the safety integrity level, the requirements related to random hardware failure, hardware failure tolerance, and systematic capability are considered according to IEC 61511 and IEC 61508 standards.
Results: The results of a case study in gas turbine and generator showed that the LOPA method is more quantitative than CRG and provides more details of independent protective layers, so it is a more suitable method for determining SIL. The SIL verification results show the SIL2 level, closer to the LOPA results.
Conclusion: The obtained results show that the function of the studied gas turbine safety instrumentation system has a suitable level of reliability and availability and is well responsive to risky conditions and possible deviations. The present approach helps safety engineers and instrumentation engineers to calculate the reliability and availability of the Function of the safety instrumentation systems of their process equipment and ensure its acceptability or not.
