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The extensive development of diverse electronic/electrical systems has led to increased exposure to electromagnetic field and can result in many adverse effects on humans, other living beings, safety operation of various equipment, etc. Electromagnetic interference (EMI) shielding materials are in greater demand to suppress this electromagnetic pollution. The present study investigates the factors affecting the shielding efficiency of carbon black-based nanocomposite shields. Fe3O4/carbon black nanocomposite (CBN) with paraffin wax were fabricated by melt mixing methods in different weight percentages of the dispersants. The EMI shielding properties of the nanocomposites were measured using a vector network analyzer in the frequency range of 8.2 to 12.5 GHz (X band) based on the transfer/reflection method. The total shielding efficiency was used to assess the shield's protection performance. Based on the weight percentages of nanocomposite constituents, four samples were obtained. The highest average of total shielding efficiency in equal thickness belonged to the sample with 50% CBN and 15% Fe3O4nanoparticles in weight. At different thicknesses, the highest average total shielding efficiency was related to the minimum thickness of 0.8 mm. Also, in with increasing the frequency decreased the mean total shielding efficiency in the samples. Depending on the type and weight percentage of nanocomposite compounds, one of the absorption or reflection mechanisms can be the main mechanism in reducing or eliminating electromagnetic waves in nanocomposite shields. The shield thickness and frequency of electromagnetic waves affect the protective performance of the shield.

In this study, a fuzzy Bayesian network (FBN) approach was proposed to analyze the domino effects of pool fire. Failure probabilities were calculated using triangular fuzzy numbers, the combined center of area (CoA)/sum-product method and the BN approach. Consequence modeling, probit equations and leaky–noisy-OR (L-NOR) gates were used to analyze the domino effects, and modify conditional probability tables (CPTs). Methanol storage tanks were selected to confirm the practical feasibility of the suggested method. The domino probability using bow-tie analysis (BTA) and FBN in the first and second levels was compared, and the ratio of variation was used for sensitivity analysis. Probability of the domino effect in the first and second levels (FBN) was 0.0071472631 and 0.0090630640, respectively. The results confirm this method is a suitable tool for analyzing the domino effects and that using FBN and L-NOR gate is a good way to assess the reliability of tanks.

Purpose. This study aimed to determine the impacts of rest breaks and stretching exercises on lower back pain (LBP) in commercial truck drivers. Methods. This quasi-experiment was carried out on 92 truck drivers suffering from chronic LBP. Subjects were categorized into three groups (stretching exercises and rest breaks, rest breaks only and reference). Pain severity and related disability were measured at the beginning of the survey and after 6 and 12 weeks. The latter was assessed using the Oswestry low back pain disability questionnaire (OLBPDQ) and the Roland Morris questionnaire (RMQ). Results. At the end of the intervention, the mean pain scores in the three groups were 2.72 ± 1.44, 4.11 ± 0.86 and 4.90 ± 1.31 respectively (p < 0.001). The OLBPDQ scores in group 1 (stretches and resting time breaks) were significantly lower than those in group 2 (rest break) (p = 0.009). The RMQ scores showed a significant reduction in group 1 compared with the other two groups (p = 0.001). Drivers in group 2 improved more significantly than those in group 3 regarding visual analog scale pain score (p = 0.049), OLBPDQ score (p = 0.024) and RMQ score (p = 0.011). Conclusion. This study provided converging results that supplementary exercises during break periods consistently help to minimize LBP and disability.

Increasing the establishment of integrated management systems (IMSs) is done with the purpose of leaving traditional management methods and replacing them with modern management methods. Thus, the present study sought to analyze the events and investigate the impact of IMS on health and safety performance indices in an Iranian combined cycle power plants.

Introduction. Most work-related musculoskeletal disorders (MSDs) are associated with improper postures and poorly designed workstations. This study is an attempt to examine the prevalence and severity of MSDs as well as anthropometric dimensions among city bus drivers. Methodology. This cross-sectional study was carried out on 60 male bus drivers. A body discomfort chart was used to evaluate MSDs. Spearman correlation was employed to examine the relationship between body size and the severity of discomfort. Results. Data analysis showed that discomfort reported in the lower back (33.3%), upper back (18.3%) and knee (15%) was severe and there was a direct and significant correlation between the body mass index and the severity of discomfort in the shoulder, arm and hip (p < 0.05). However, the results showed that eye sitting height and sitting height had significant inverse relationships with discomfort in the ankle and elbow (p < 0.05). Conclusion. The results of the study can be used to address ergonomic risk factors and reduce their associated disorders. The findings of the study can be used in training programs to educate drivers how to decrease the risk associated with work-related MSDs by adopting appropriate behavior strategies.

Work-related musculoskeletal disorders are among the major health problems of tailors. This study was conducted with the aim of evaluating posture type, assessment of pain in body parts and the impact of education on the frequency of such injuries in tailors. This interventional study was performed in two groups of male tailors (45 cases, 45 controls) using Quick Exposure Checklist (QEC) software and the Nordic musculoskeletal questionnaire. The relationship between the qualitative variables was examined by χ2test. Three months after the educational course, there was a significant decrease in the frequency of pain in most of the body parts (p < 0.05); mean of the QEC scores before the intervention was 79.04 ± 80.02 compared with 70.4 ± 8.3 after the intervention. It is suggested to hold cyclical educational courses along with other intervention programs for reducing the risks and dangers in the tailors.