Showing 46 results for Ba
Fateme Dehghani, Seyed Abolfazl Zakerian, Asma Zare, Fariborz Omidi, Zahra Moradpour, Abouzar Eynipour, Masoud Ghanbari Kakavandi,
Volume 6, Issue 4 (12-2016)
Abstract
Introduction: A high percentage of musculoskeletal disorders in workplaces occur due to awkward posture and non-ergonomic design of the work stations for lifting and carrying of materials. To avoid these injuries, jobs should be designed in a way that ergonomics risk factors are controlled properly. The aim of this study was to utilize ergonomics interventions to minimize ergonomics risk factors in bag packing unit in a mineral processing plant.
Material and Method: This cross sectional study was carried out among 20 workers of bag packing unit. Camera recording of working postures, evaluation of medical records, interview, and REBA technique were used to identify the ergonomic risk factors. Interventions included changing the conveyor belt height and the use of spring pallets (spring table). Data were analyzed using Paired T-Test by SPSS software version 18.
Result: Before implementing ergonomics intervention, a total of 75% of evaluated postures by REBA technique obtained score of 8-10 (very high risk level) and 25% had score of 11-15 (very high risk level) that correspond to the action level 3 and 4, respectively. Following the implementation of ergonomics interventions, a total of 90% of the analyzed postures showed action level 2 (moderate risk level) and the remainder 10 percent of evaluated postures showed high risk level. Comparison of REBA technique scores before and after implementing interventions showed a significant difference (P-value < 0.05).
Conclusion: Based on the findings of this study, the implementation of ergonomics interventions has remarkably decreased the required action level and it may be able to improve work-related postures.
Mohammad Reza Monazzam Esmaielpour, Fereydoon Laal, Fereshte Majlessi, Rohollah Fallah Madvari, Abbas Rahimi Foroushani, Alireza Fallah Madvari,
Volume 7, Issue 4 (12-2017)
Abstract
Introduction: The use of hearing protective devices (HPDs) is the last way for noise control. It is important to know the information about the duration time using these devices to ensure protetion effectiveness. The aim of this study was to investigate the effect of increasing duration time of the using of the devices on hearing loss in tile industry workers with application of the BASNEF education model.
Material and Method: Task Base Method (TBM) and ISO9612(2009) standard methods through a noise dosimeter device were used to exmine workers’ noise exposure level when they didn’t used of HPDs. Actual performance of HPDs was determined by using the NIOSH standard before and after training intervention and measuring time of use and protection device type. Data were analyzed using SPSSVv19 and conducting t-test and ANCOVA statistical tests.
Result: Before training intervention, the actual noise level for case workers was 89.76 dBA. On the contrary, this value was 84.04 dBA for after intervention, with a significant difference with control group (P<0.0001) using ANCOVA analysis. In control group, the actual level of noise has not changed because this group has not received any training.
Conclusion: The results revealed that, based on BASNEF education model, duration time of using hearing protection devices is effective on increasing their function and performance.
Farnaz Valedeyni Asl, Sadegh Hazrati, Mohsen Arzanlo, Mehdi Fazlzadeh,
Volume 8, Issue 1 (4-2018)
Abstract
Introduction: Microorganisms in hospitals are potential sources of infection to patients and staffs. Bioaerosol exposure is associated with a vast range of adverse health effects including infectious diseases, acute toxic effects, allergy. This study aimed to survey the type and density of bioaerosols in ambient air of different wards of educational hospitals Ardabil in 2016.
Material and Method: This cross-sectional study was conducted in 2 educational hospitals of Ardabil city in 2016. ZTHV02 sampler and Tryptic soy Agar along with Cycloheximide antibiotic were used to evaluate and determine the airborne bacterial counts. The average sampling time was 10 minutes. Air samples were transported to the lab just after sampling and incubated for 48 hours at 37 ºC. Then, raised colonies were counted. Bacterial density was expressed as CFU/m3 ± SD.
Result: Mean bacterial concentrations were 10.3 and 23.4 CFU/m3 in Imam and Alavi hospitals, respectively. X-ray room in Imam Khomeini hospital and ICU room in Alavi hospital had the highest bacterial count. But, the least bacterial loads were observed in ICU and Angiography wards of Imam Khomeini and CTSCAN ward in Alavi hospitals. The most prevalent bacteria species isolated from air samples of Imam hospital was Enterococcus spp followed by Pseudomonas spp, coagulase negative Staphylococci spp and Non -Enterococcus group D Streptococci and for Alavi hospital; Coagulase negative Staphylococci spp followed by Psodomonas spp, Klebsilla spp and, Enterococcus spp.
No significant correlations were found between bacterial counts, temperature and humidity of the sampling sites. However, bacteria density significantly were higher in morning shift comparing to evening shift (P <0.05).
Conclusion: High concentration of airborne bacteria bio-aerosols in Ardabil hospitals can be important health risks for health workers and the patients.
Bahman Pourhassan, Farideh Golbabaei, Mohammad Reza Pourmand, Somayeh Farhang Dehghan, Ensieh Masoorian,
Volume 8, Issue 3 (9-2018)
Abstract
Introduction: Indoor air environments contain a wide variety of microorganisms such as bacteria, fungi, and viruses in which some of them can affect the human health. Filtration is considered as one of the most common methods to remove microorganisms in these environments. The purpose of current study was to investigation the neat and photocatalytic HEPA filters performance at different face velocities and various intensity of UVC light source on the reduction of airborne microorganisms.
Material and Method: After installation of the neat and photocatalytic HEPA filters in a closed–loop chamber, suspension of Staphylococcus epidermidis and Bacillus subtilis bacteria with a concentration of 107 CFU / ml were sprayed into the closed–loop chamber by nebulizer. Sampling of penetrated microorganisms from filters were performed using the NIOSH 0800 method under ambient temperature 22±3oC, relative humidity 35±5%, and different air velocity (0.1 m/s and 0.3 m/s) and UVC different radiation intensity (1 mW/cm2, 1.8 mW/cm2 and no radiation (dark)) at 30 minutes time period. penetrated microorganisms density from filters was determined in term of CFU/m3.
Result: There were no significant differences in the penetration rates of microorganisms at the dark mode between the two neat and photocatalytic HEPA filters (p>0.05). The penetration rate of bacteria was significantly decreased in the neat and photocatalytic HEPA filters at UVC radiation mode with various intensities than dark mode (p<0.05). In addition, comparison of the filters in the illuminance modes of 1 mW/cm2 and 1.8 mW/cm2 were statistically significant (P <0.05). Also, UVC radiation with the 1.8mW/cm2 illuminance compared to the 1 mW/cm2 illuminance resulted in a greater reduction in the bacterial penetration from both types of filters, which is statistically significant(p<0.05). The bacteria penetration rate dramatically increased by increasing the face velocity from 0.1 m/s to 0.3 m/s under UVC radiation at an illuminance of 1mW/cm2, 1.8mW/cm2 and as well as in no radiation mode in both types of HEPA filters (P <0.05).
Conclusion: Photocatalytic HEPA filters and increasing UVC illuminance, especially at lower surface velocities, have a significant positive effect on reducing airborne microorganisms and increasing the efficiency of HEPA filters
Mojtaba Zokaee, Mohsen Falahati, Hadi Asady, Masoud Rafee, Mohammad Najafi, Azam Biabani,
Volume 9, Issue 2 (6-2019)
Abstract
Introduction: Throughout the world, many efforts have been made to provide suitable tools for achieving sustainable urban development and the achievement of a sustainable city. Establishing a Health, Safety and Environment Management System (HSE-MS) is one of the tools for achieving sustainable urban development. Measuring the performance of an organization in the HSE area is a precondition for continuous improvement, which is the spirit of the new HSE management systems. Therefore, the main purpose of this research was to provide a practical model for quantitative ranking of different areas of Tehran municipality in terms of HSE performance with using of multi-criteria decision-making method.
Material and Methods: In this descriptive-applied study, after determining functional axis and performance evaluation indicators related to each of them (29 functional axis and 154 performance evaluation indicators), through designing a questionnaire and based on the views of the expert group, weight of functional axis and performance indicators were determined using a hierarchical process analysis technique.
Results: In this study, the weighted value for functional axis of the process based HSE in comparison to the result based HSE were higher. “Commitment and Leadership” and “HSE Certificate of Occupations” for the process based HSE, “Safety” and “Health” for the result based HSE, and “Economic Sustainability” and “Architecture and Urbanism” for urban management had the higher and lowest weighted values.
Conclusion: The results of assessment and validation of selected indicators and functional axis showed that in designing and determining the HSE performance assessment model of municipalities, in addition to the axises and indicators of the HSE domain, factors affecting urban management can have a significant impact on the performance of municipalities in the field of HSE.
Rezvan Ghashghaei, Gholam Reza Sabzghabaei, Soolmaz Dashti, Samira Jafari Azar, Farhad Salehipour,
Volume 9, Issue 2 (6-2019)
Abstract
Introduction: The accidents involving the transport of hazardous goods in ports have always been one of the human and environmental threats. The purpose of this research is to study the consequences of incidents involving dangerous goods by modeling and prediction of catastrophic consequences of these goods using the Software valid of management, so in addition to the affected area of the various outcomes of these goods, To provide the necessary management measures to reduce human and environmental toll on keeping dangerous goods in ports and warehouses to be paid.
Material and Methods: The study performed from PHAST and ALOHA software in the container terminal in the region of Bandar Imam Khomeini and, to verify the consequences of styrene of toxicity of dangerous goods, was used.
Results: According to the results of this study, the extent of pollution coverage (the forbidden region) at least a radius of 79 meters and the best place for placement the Support groups are a radius of 106 meters, around the area dangerous goods. Finally, to offer management practices to avoid or reduce the consequences of possible sites and warehouses storing goods in the study area was dangerous.
Conclusion: In this study, methanol reservoir was introduced as the main focus of risk; therefore, the implementation of safety rules, eliminating mechanical failures, personal protection and education, and effective measures to prevent and fight fire are proposed for decreasing the probable losses and fatalities are necessary. As well as measures such as drainage design and appropriate land cover of hazardous goods and predictions for emergency evacuation with regard to atmospheric conditions (speed and wind direction) were recommended.
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.
Adel Mazloumi, Zeinab Kazemi, Saeed Abedzadeh, Abbas Rahimi Foroushani,
Volume 11, Issue 1 (3-2021)
Abstract
Introduction: Workers in car manufacturing industry are at risk of a high prevalence of musculoskeletal disorders, especially low back pain. Therefore, in the present study aimed to design and fabricate a portable device to evaluate the low back kinematics and to compare these variables in workers with and without low back pain (LBP) in assembly lines of an automotive industry.
Material and Methods: In the present research workers postures were assessed using OWAS direct observational method. Moreover, simultaneously, prevalence and intensity of low back pain were evaluated by Dutch Musculoskeletal Questionnaire (DMQ) and Visual Analogue Scale (VAS). After fabricating motion analysis device, a field study was conducted using the designed device among 16 volunteers to investigate low back kinematic variables in two groups of workers: LBP and non-LBP.
Results: The results showed that 62.1 percent of all working postures were high risk with corrective action levels of 3 and 4. On average, 86.1 percent of workers experienced LBP in the previous 12 months. Regarding comparison of kinematic variable in the two groups of LBP and non-LBP, workers without LBP had higher degree and duration (in second) of movements (forward flexion, lateral bending, extension, and twisting), as compared to those with LBP. However, only movement range of forward flexion in non-LBP group (mean: 64.29 and SD: 8.41), was significantly higher than those with LBP (mean: 58.97 and SD: 11.34).
Conclusion: The device can be used as an effective tool in the ergonomics studies in the field of back pain, due to its potential to record the kinematics of the trunk, as well as its lightweight and non-interference with the task. Device’s validity was acceptable based on the comparison of the results of this device with those obtained from inclinometer.
Esmaeil Karami, Mohammadreza Monazzam, Keykaous Azrah, Mehdi Mohammadian, Zahra Goodarzi,
Volume 12, Issue 1 (3-2022)
Abstract
Introduction: Over recent years, various programs have been conducted to reduce noise, indicating the increasing concerns of society over noise pollution. This study has been performed to enhance the performance of parallel barriers on two sides of a highway considering the surrounding buildings.
Material and Methods: The 2D boundary element simulation method was employed to predict the noise reduction in barriers. Regarding the effect of buildings and water canals, various kinds of models were investigated to compare the effectiveness of different boundary barriers in real conditions from a listener’s perspective.
Results: The use of a single YA model could improve the performance of parallel barriers by 3.5 dB compared to that of a TS model. Moreover, by using a pair of barriers, no significant change was observed in the performance of the second barrier. However, by using parallel barriers along the surrounding buildings, the TD model improved the efficiency by 3 dB compared to the TS model. The rise in the frequency resulted in remarkable adverse effects on the barrier performance, such that the surrounding buildings at a distance of 8 m had a negative effect on the performance of the parallel barriers by almost 8.34 dB.
Conclusion: In general, by ignoring the buildings, the use of a pair of TZ barriers showed a higher performance. Meanwhile, by considering the buildings in the design model, the TD model was found to be optimum. Therefore, it can be concluded that choosing an ideal barrier only based on the noise behind it cannot indicate its behavioral and acoustic characteristics in a real environment.
Fateme Heydari Abdolahi, Ali Safari Variani, Mohammad Soleimanabadi, Sakineh Varmazyar,
Volume 12, Issue 1 (3-2022)
Abstract
Introduction: The purpose of the current study was to predict the percentage of the sway index from the static balance point based on the anthropometric dimensions of construction workers.
Material and Methods: This descriptive-analytical study was conducted on 114 construction workers. First, the construction workers were asked to complete the demographic questionnaire and the inclusion criteria were determined. Then, the anthropometric dimensions were measured. Afterward, the static balance of participants was assessed with their open eyes and standing position using a Stabilometer device. The obtained data were analyzed using Pearson correlation and multiple linear regression.
Results: 29.8% of construction workers were in weak and very weak classes in terms of static balance. The Pearson and spearman’s correlation coefficient showed a significant relationship between age, weight, and sway index of individuals. In addition, multiple linear regression showed that age, weight, and foot surface of construction workers can predict the percentage of the sway index from the static balance point among construction workers.
Conclusion: The results of the current study indicated that demographic information such as age, anthropometric parameters of weight, and foot surface are effective factors on static balance in a healthy construction workers’ community with a normal body mass index.
Zahra Alaei, Roohollah Ghasemi, Mohammad Reza Pourmand, Ali Karimi, Ensieh Masoorian, Farideh Golbabaei,
Volume 12, Issue 2 (6-2022)
Abstract
Introduction: Volatile organic compounds are the most common pollutants in the air, and among them, toluene is the most common form, which is toxic resulting in liver and kidneys damages. Regarding the fact that this compound is widely used in various chemical industries, implementing an efficient method for controlling its concentration is of great importance. The comparative survey of the capability of virgin activated carbon with the one immobilized by pseudomonas putida PTCC, and also the performance of the biofiltration system involving pseudomonas putida bacteria immobilized on activated carbon for the adsorption and degradation of toluene from the air as well as regenerating the activated carbon were aimed in the present study.
Material and Methods: The microbial growth process was initiated by incubation of pre-culture in a rotary shaker, at 150rpm overnight. After 4 days, the strain pseudomonas putida, PTCC No: 1694 was immobilized on a certain amount of activated carbon. Subsequently, an airstream containing toluene was introduced into the biofilter, and the inlet and outlet concentrations of toluene were measured.
Results: The obtained results illustrated that the increase in the volume of the media and decrease in the gas flow rate significantly enhances efficiency. The great performance of the biofilter was confirmed by the high efficiency of the immobilized activated carbon which exhibited 89% yield during 14 hours. On the second cycle, the biofiltration system was able to adsorb toluene at an efficiency of 81%, while the virgin activated carbon exhibited far less efficiency with the value of 28%.
Conclusion: The provided results demonstrated the feasibility and reusability of the biofilter system for toluene removal. The proposed technique also extends the activated carbon’s capacity, which could be a potential solution to re-use the activated carbon in industrial applications.
Masoud Feyzi, Ali Jafari, Hojat Ahmadi,
Volume 12, Issue 2 (6-2022)
Abstract
Introduction: Due to the non-developed mechanization situation, chainsaw is a widely used tool in Iranian forests. This tool can trigger unwelcome disorders (e.g., white finger syndrome) due to the transmitted vibrations from its handle to the body members. Characterizing these vibrations can result in minimizing the intensity of these disorders. This study aims to investigate the effect of different hardwood species (Beech, Hornbeam, and Alder) on the vibrations transmitted to the wrist and arm.
Material and Methods: Experiments are conducted during four operations including Beech-, Hornbeam-, and Alder-cross-cutting and without cutting as the control sample. Vibration accelerations in three directions of a local Cartesian coordinate system are measured at three points including chainsaw handle, operator's arm and wrist. Using the time and frequency spectra of vibration accelerations, root mean square (RMS), total vibration acceleration, total vibration transmissibility, and frequency-weighted vibration acceleration are calculated based on ISO 5349 (2001) and ISO 10819 (2013) standards. The calculated parameters were statistically analyzed in SAS.
Results: The results showed that variations in wood species could significantly affect the RMS at all three points. The RMS magnitude decreases from handle towards the arm. Interestingly, a significant variation in vibration transmissibility is observed in different frequencies. This study confirms that body organs can damp the high-frequency vibrations better than the low frequency ones.
Conclusion: Although the RMS for cutting operations is less than the control sample, frequency-weighted vibration acceleration and consequently the risk of white finger syndrome is higher in cutting regimes. Furthermore, some vibration accelerations (below 40 Hz for wrist and below 25 Hz for arm) are amplified during transmission despite significant damping in total vibrations.
Faeze Sarraf, Ali Safari Variani, Sakineh Varmazyar,
Volume 12, Issue 2 (6-2022)
Abstract
Introduction: Using backpacks has arisen complaints regarding musculoskeletal pains among students. The aim of this study is to investigate the relationship between demographic information and bag weight with Neck Disability Index (NDI), angles and head and neck postures among students.
Material and Methods: This descriptive-analytical and cross-sectional study was conducted among 80 students who were selected randomly. Demographic information and NDI questionnaires were used for data collection. The head and neck tilt angles and the amount of change in the forward head posture were determined using the photogrammetry method and Kinovea software.
Results: A negative and significant correlation was observed between head tilt angle with age (r = - 0.27) and neck tilt angle with body mass index (r = - 0.37). Also, a positive and significant correlation was observed between the amount of change in the forward head posture and body weight (r = 0.24). The head tilt angle was significantly different in male and female students at different educational levels. NDI (r = 0.23) and neck tilt angle (r = 0.26) also increased significantly with increasing bag weight.
Conclusion: Reviewing the standard weight of bag and changing the lifestyle can play an important role in improving the head and neck angles and postures.
Maryam Feiz-Arefi, Fakhradin Ghasemi, Omid Kalatpour,
Volume 12, Issue 3 (9-2022)
Abstract
Introduction: Oxygen-generating central plays a vital role in the continuous performance of hospitals. Any leakage or failure in this section can not only endanger the health and safety of patients but also cause fire and explosion. Probabilistic risk assessment is a useful tool for identifying the main root causes of leakage in oxygen-generating central. This study aimed at risk assessment of an oxygen-generating central in a hospital in Hamadan using fuzzy sets theory and Bayesian networks.
Material and Methods: First, all root causes supposed to contribute to oxygen leakage from any part of the oxygen-generating central were identified, and based on them a fault tree analysis (FTA) was constructed. Then, the FTA was mapped in a BN. The failure probability of root causes was calculated using fuzzy sets theory and experts’ opinions. Belief updating based on BN was utilized for subsequent analyses.
Results: According to this study, ignorance of labels on the oxygen generation and distribution system is the most important root cause leading to oxygen leakage. Moreover, removing masks from patient’s faces is the main cause of oxygen leakage in patient rooms. Once leakage occurred, the presence of an ignition source can lead to fire or explosion.
Conclusion: oxygen leakage can create considerable risks in hospitals. All staff should be provided with sufficient training regarding hazards of oxygen-generating and distributing systems and oxygen leakage. Particular attention should be paid to such leakages and their adverse consequence in emergency planning and hospital crisis management.
Ehsan Ramezanifar, Kamran Gholamizadeh, Iraj Mohammadfam, Mostafa Mirzaei Aliabadi,
Volume 13, Issue 1 (3-2023)
Abstract
Introduction: Risk assessment is a scale for predicting reliability and can manage interactions between components and process variables. Moreover, the reliability of one component or barrier affects the overall risk of the system. Being one of the most critical safety barriers of the storage tank, the failures of Fixed Foam Systems (FFS) on demand can result in severe consequences. FFS, is of grave importance in decreasing the risks associated with fires and damages.
Material and Methods: This study aims to determine the probability of root causes related to FFS failure through Fuzzy Fault Tree Analysis (FFTA) to estimate system reliability. In conventional fault tree analysis, accurate data is usually used to assess the failure probability of basic events. Therefore, the introduced approaches were employed to quantify failure probabilities and uncertainty handling. Finally, system reliability was estimated according to the failure probability of the top event.
Results: The findings showed that 13 baseline events involved FFS performance. According to the results, failures of cable path and detection system (or resistance temperature detectors), set the activation switch (multi-position) incorrectly, and foam makers not continuously running are the three most critical basic events influencing the reliability of fixed foam systems. In addition, this paper estimated the system reliability at 0.8470.
Conclusion: The results showed that the FFTA could be used in matters such as reliability evaluation failure and risk assessment using experts’ judgment. This paper can also show the adaptation of the fuzzy approach to assess the failure probability of the basic event in the fault tree analysis (FTA).
Zeinab Kazemi, Adel Mazloumi, Navid Arjmand, Zanyar Karimi, Ahmadreza Keihani, Mohammad Sadegh Ghasemi,
Volume 13, Issue 2 (6-2023)
Abstract
Introduction: Given the high prevalence of low back pain in manual handling activities, its known relationship with spinal loads, and the role of muscular fatigue and the body’s adaptive mechanisms to counteract fatigue, this study investigated the effect of repetitive lifting tasks on trunk muscular fatigue and the kinematics of the spine and load-in-hand.
Material and Methods: Eighteen male volunteers lifted a box from the floor to their waist height at a pace of ten lifts per minute until they could no longer continue the task and reported the highest level of exhaustion. Kinematic data and muscle electromyographic activity were simultaneously recorded using a motion capture system and an electromyography device. In this study, average trunk flexion angle and trunk angular velocity were calculated as trunk kinematic variables, while average box vertical travel distance, average box horizontal displacement from L5-S1, and average box vertical displacement velocity were considered as box kinematic variables. The median frequency of electromyographic signals from selected muscles was quantified as a muscle fatigue indicator. Since subjects performed different lifting cycles, the total number of cycles was divided into five distinct blocks for data analysis.
Results: The results showed significant effects of lifting trial blocks on trunk angle (p=0.004) and vertical box displacement (p<0.001). Median frequency was significantly affected by lifting blocks for right (p=0.016) and left erector spinae (p=0.014), right (p=0.021) and left multifidus (p<0.001), right latissimus dorsi (p=0.001), and left rectus abdominis (p=0.039).
Conclusion: Overall, the results highlight variations in most kinematic parameters and a reduction in the frequency content of EMG signal spectra. These changes serve as indices of the central nervous system’s control over lifting behavior under dynamic conditions. A better understanding of these central nervous system adaptations could have practical applications in interventions such as workstation design, exoskeleton development, and worker training to manage musculoskeletal disorders.
Hassan Mehridiz, Mohamad Sadegh Ghasemi Ghasemi, Hassan Saeedi, Mahsa Varmazyar, Ehsan Garosi,
Volume 14, Issue 2 (6-2024)
Abstract
Introduction: Lifting loads in awkward postures is a main cause of low back musculoskeletal disorders. In this context, researchers have used various indicators to determine the relationship between biomechanical variables and the risk of these disorders. This study aimed to investigate the correlation between plantar pressure distribution and the values of UTAH back-compressive forces (BCF) and lifting index (LI) during symmetrical load-lifting tasks.
Material and Methods: Thirteen healthy men, aged 25 to 35, took part in this study. The participants were instructed to symmetrically lift loads weighing 7.5 kg and 15 kg in 15 different postures, considering three horizontal distances (A, B, C) and five different heights (1-5). Pressure on the foot soles was recorded using 16 force-sensitive resistors (FSR) corresponding to eight anatomical areas on each foot. The BCF and LI were also calculated using the UTAH method and the NIOSH equation, respectively. Statistical analysis was performed using SPSS (version 21) software.
Results: Based on the results, when the load was closest to the body (A1-A5), the highest pressure was recorded in the heel and the 4th and 5th metatarsal of both feet. In lifting a load of 15 kg in the A2, B1, B2, C1, C2 postures and lifting a load of 7.5 kg in the C2 posture, the average BCF exceeded 700 pounds. The LI was greater than 1 for specific postures (B1, B2, B4, B5, C1-C5) at 15 kg and (C1, C2, C4, C5) at 7.5 kg load-lifting. During the 7.5 kg and 15 kg load-lifting, there was a significant correlation between the plantar pressure and the values of LI and UTAH (p-values < 0.05) in most postures.
Conclusion: The results showed a significant correlation between plantar pressure distribution and load-lifting postures. The study findings, which identify risk levels associated with lifting postures, lay the groundwork for future research aimed at categorizing safe and unsafe plantar pressure patterns.
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.
Saba Kalantary, Mohammad Reza Pourmand, Ensieh Masoorian, Mirghani Seyd Someah, Zahra Barkhordarian, Sara Hajinejad, Farideh Golbabaei,
Volume 14, Issue 2 (6-2024)
Abstract
Introduction: Protection of the respiratory system has been a vital, and for this purpose, various solutions have been proposed, including the use of masks. One of the most important parameters to measure the effectiveness of the mask against the penetration of microbial agents. The present study was conducted with the aim of evaluating the bacterial and particle filtration of medical masks.
Material and Methods: To assess bacterial performance, the national standard 6138, compliant with EN14683, and Type I medical masks were utilized. Staphylococcus aureus bacterial suspension was prepared and passed through the mask using a nebulizer and through an impactor with a flow rate of 28.3 l/min. Plates containing soy agar were placed in the impactor. Subsequently, all plates were incubated, and the bacterial filtration efficiency (BFE) of the masks was determined by counting the bacterial colonies that passed through the mask’s media as a percentage of the total bacteria. It is worth noting that the pressure drop and particle filtration efficiency were also determined for all masks
Results: Based on the results of the particle removal performance for the particle size of 3 µ, the masks were categorized into three groups with efficiency above 99%, above 95% and 90%. According to the standard, all masks had an acceptable pressure drop below 40 Pa. The acceptable bacterial filtration rate for type I masks should be above 95%. The results showed that type A and B masks have an acceptable bacterial filtration rate and there is a significant correlation between the types of masks examined in terms of bacterial and particle efficiency.
Conclusion: The results showed that different types of masks under investigation have significant differences in terms of particle capture efficiency and bacterial filtration performance. In addition, there is a significant correlation between bacterial and particle filtration efficiency.
Zahra Khodabakhsh, Leila Omidi, Khadijeh Mostafaee Dolatabad, Matin Aleahmad, Hossein Joveini,
Volume 14, Issue 3 (10-2024)
Abstract
Introduction: Domino effects are a chain of low-probability and high-consequence accidents in which a primary event (fire or explosion) in one unit causes secondary events in adjacent units. Bayesian networks have been used to model the propagation patterns of domino effects and to estimate the probability of these effects at different levels. The unique modeling and flexible structure provided by Bayesian networks allow the analysis of domino effects through a probabilistic framework, taking synergistic effects into account.
Material and Methods: Firstly, collecting the basic information related to the location of the storage tanks and determining the scenario of the accidents were done. Furthermore, the values of the heat radiation as escalation vectors in case of a fire in one tank were determined using ALOHA software. The received heat flux values were compared with the heat radiation threshold of 15 kw/m2 and the escalation probability of the primary unit and the propagation of the initial scenario to nearby storage tanks were determined using Bayesian networks.
Results: The analysis of the heat flux values showed that among the 8 studied storage tanks, two storage tanks had the highest potential for spreading domino effects due to their location in a tank farm. Also, the implementation of Bayesian networks in GeNIe revealed that, compared to other storage tanks, the probability of domino effects propagating to other nodes is higher when a primary fire accident occurs in the two mentioned tanks, while considered as primary units.
Conclusion: Domino effect modeling and appropriate preventative measures can decrease the escalation probability in the process industries. Consideration of the synergistic effects of events at different levels by taking the escalation vectors into account leads to proper risk management and the determination of emergency response measures in storage tank farms.
