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Investigation of past accidents has shown that LPG tank accidents cause significant damage to the industry due to the storage of large volumes of flammable materials in them. This study aimed for developing a predictive accident model for dynamic risk assessment of propane storage tanks of the refinery. Hazards and safety barriers were identified using MIMAH methodology. The basis of MIMAH methodology is Bow-tie method. To construct the Bow-tie diagram, first, accidents that occurred on LPG tanks were extracted from the databases of accidents and valid sources. The top events of the accidents were identified and analyzed by the fault tree. The Bow-tie diagrams were constructed and the barriers on the diagrams were identified and verified by
Accidents of liquid pipelines are occurring around the world for various causes and have major consequences. Identification of pipeline accident causes is a primary and basic action for prevention of accidents. Also, survey of consequences can help a management for risk assessment. This study presents a review of liquid pipelines leak, fire and explosion scenarios causes and consequences. The accidents of liquid pipelines were collected from accident databases, papers and other sources. The causes and consequences of the 81 accidents were classified. The most frequent causes of accidents were corrosion with 19%, sabotage with 15% and improper repair and maintenance with 12%. Identification of pipelines accidents causes and consequences can
Sulfur dioxide, a noxious air pollutant, can cause health and environmental effects, and its emissions should be controlled. Nonthermal plasma is one of the most effective technologies in this area. This study evaluated the efficiency of a packed-bed plasma reactor (PBR) and in-plasma catalysis (IPC) in SO 2 removal process which were finally optimized and modeled by the use of the central composite design (CCD) approach. In this study, SO 2 was diluted in zero air, and the NiCeMgAl catalyst was selected as the catalyst part of the IPC. The effect of three main factors and their interaction were studied. ANOVA results revealed that the best models for SO 2 removal efficiency and energy yielding were the reduced cubic models. According to th
IntroductionA vast amount of research has been conducted to identify human and organizational factors that contribute to the occurrence of occupational incidents. Considering the identified factors, the question is how much the occupational incident probability will decrease in the absence of one or more recognized contributory factors.MethodsTwenty-one fatal accident reports were selected for Root Cause Analysis (RCA). The contributory factors were identified by content analysis of the accident scenarios. A 5-point Likert questionnaire was developed to measure the probability of identified factors. Using the identified contributory factors and their corresponding probabilities, a Bayesian network model was constructed for estimating the pr
Atmospheric storage tank fires are relatively rare, but because of storing large amount of flammable liquid in them, they have catastrophic consequences. This study presents a review of atmospheric storage tank fire scenarios causes and costs. The fire accidents on the atmospheric storage tanks were collected from accident databases, papers and other sources. The causes and costs of the 104 accidents were classified. Initiating event of 38% of the accidents was environmental factors, 20% was equipment factors, 15% was operation factors (human error), 13% was domino effect, 10% was maintenance factor and 4% was terrorist attack. Lightning strikes were the most frequent cause of the accidents triggered by the environmental factors (21.73%). T
Air pollution is a major health problem in developing countries which has adverse effects on human health and environment. Non-thermal plasma (NTP) is an effective air pollution treatment technology. In this research, the performance of dielectric barrier discharge (DBD) plasma reactor packed with glass and ceramic pellets were evaluated in removal of SO2 as a major air pollutant, from air in ambient temperature. Response surface methodology (RSM) was used to evaluate the effect of three key parameters (gas concentration, flow rate, and voltage) as well as their simultaneous effects and interactions on SO2 removal process. Reduced cubic models were derived to predict the SO2 removal efficiency (RE) and energy yielding (EY). Analysis of vari
Background: Organophosphorus (OP) compounds are considered among the most common insecticides. The major mechanism of organophosphorus toxicants includes inhibiting cholinesterase enzyme. organophosphorus toxicants cause impaired thyroid hormones through affecting different parts of the hypothalamus-pituitary-thyroid axis. The aim of this study is to determine the effects of chronic exposure to organophosphorus pesticides on thyroid function. Methods: The present descriptive-analytical study was conducted cross-sectionally on male workers employed in a factory producing OP as the exposure group as well as the personnel of the administrative department of the same factory as the control group chosen through census method. According to Helsin
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),
Background Optimizing the geometry of an inhalation exposure chamber (IEC) results in a uniform and stable distribution of the test atmosphere and enables the modeling of its performance. This study was conducted for the first time to optimize and model the performance of an IEC. Methods The current study was performed on the initial design of the ASRA chamber and to optimize and model it. The matrix of experiments was determined by the design expert software (DE7). The mean of particle concentration (MPC) in the respiratory zone of animals as the response variable, and height of the cylindrical section of the chamber, carrier gas density, inlet concentration, and particle aerodynamic diameter (da) as independent variables were considered.
Among fibers with lignocellulosic origin, Kenaf fiber, because of its advantages and as a sustainable alternative to synthetic fibers has received increasing attention for manufacturing hybrid composites with reasonable acoustical and physical properties. The present study deals with the impact of chemical treatment of Kenaf fibers on the overall properties of hybrid composites fabricated from these fibers. Also, the results from predictive analytical model of sound absorption for these composites were employed for comparison with the experimental findings. Kenaf fibers were treated at room temperature with 6% concentration of sodium hydroxide (NaOH) and 4 h immersion time. Having manufactured the composites with the treated and untreated
In this study, barriers elements and initiating events of accidents and their risk influence factors were identified and classified according to a developed conceptual model, relationship between the risk influences factors were determined using a fuzzy DEMATEL model, the risk influence factors weight was determined using a fuzzy AHP model and conditional probability table of the risk influence factors was obtained using R?ed method. The probability of the initiating events and the barrier elements failure was determined using fuzzy logic. The barrier elements and the initiating events were modeled by mapping bow-tie in Bayesian network. The Bayesian networks of risk influence factors were constructed by mapping the fuzzy DEMATEL outputs in
Background Optimizing the geometry of an inhalation exposure chamber (IEC) results in a uniform and stable distribution of the test atmosphere and enables the modeling of its performance. This study was conducted for the first time to optimize and model the performance of an IEC. Methods The current study was performed on the initial design of the ASRA chamber and to optimize and model it. The matrix of experiments was determined by the design expert software (DE7). The mean of particle concentration (MPC) in the respiratory zone of animals as the response variable, and height of the cylindrical section of the chamber, carrier gas density, inlet concentration, and particle aerodynamic diameter (da) as independent variables were considered.
Many workers are exposed to health problems arising from molds, fungi, and their toxins during waste processing. Aflatoxin B1 (AFB1) level in airborne and settled dust, aflatoxin B1-albumin (AFB1-Alb) adduct in serum, liver and kidney biochemical tests, and body redox change of workers in municipal dry waste-processing sites were investigated. The surface, personal, and area air dust and the blood of workers’ samples were collected from the plastic and bread waste-sorting sections in three recycling municipal dry waste sites. Digestion (only for serum samples), passed through SPE cartridge, elution, and collection with methanol, immune-affinity column clean-up, and HPLC system equipped with post-column derivatization method and fluoresce
BACKGROUND:Exploring experiences of individuals for barriers they confront relating to safety could help to design safety interventions with an emphasis on the most safety influencing factors.OBJECTIVE:This study strived to present an empirical exploration of individuals’ experiences across the petroleum industry at different levels of the organizational structure for factors that influence occupational accidents.METHOD:Based on accidents history, face-to-face semi-structured interviews were conducted with individuals who engaged in fatal activities, as well as authorities responsible for managing safety. The qualitative content analysis of 46 interview transcripts was conducted using MAXQDA software.RESULTS:A three-layer model comprising
Potassium permanganate (KMnO4) is a dominant ethylene (C2H4)-scavenger extensively used in fresh horticultural commodities, mainly in climacteric fruit, to prolong their shelf life. This material has been traditionally utilized as a C2H4-permeable sachet for inclusion into packages of produces. New formulation strategies are required in polymeric materials to develop nanocomposites with ethylene scavenging potential, as well as good barrier and mechanical properties. This work involved preparation and optimization of novel interesting nanocomposites based on polyolefin elastomer (POE) comprising impregnated nanoparticles (nanosilica (NS) and nanoclay (NC)) with KMnO4 via the response surface methodology (RSM). Regression models were develop
The present study aimed to investigate the effect of alkali (NaOH) treatment on the morphological properties and tensile strength of Yucca Gloriosa (YG) natural fibers along with the optimization of the parameters related to such treatment. The Response Surface Methodology (RSM) with Central Composite Designs (CCD) approach for the design and analysis of experiments with the optimization of NaOH concentration and immersion time was applied. Also, the Scanning Electron Microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were also employed to evaluate and compare the morphological and structural properties of YG fibers. For NaOH treatment process the best mathematical models to predict th