Ergonomic Assessment of Workstations and Musculoskeletal Disorders Risk Assessment in the Central Oil Refinery Workshop of Hormozgan Province

Background: Working station includes the physical environment and arrangement of all equipment in the work place. Work-related musculoskeletal disorders are among the most common occupational injuries. The purpose of this study was ergonomic assessment of workstations, determining the prevalence of musculoskeletal disorders and assessing the physical condition of the workers. Methods: This descriptive and analytical cross-sectional study was conducted on 40 workers of the Central Workshop Oil refinery in Hormozgan. Worker postures were evaluated by Rapid Upper Limb Assessment (RULA) method. Finnish checklist was used to analyse workstation condition and Nordic Questionnaire was used to estimate the prevalence of musculoskeletal disorders. Data were analyzed using descriptive statistics and Logistic regression through SPSS16. Results: In 5% of cases, work environment condition was poor, in 5% of the cases, the pressures applied to the elbow and wrist, were severe and legs and buttocks were in poor condition.The prevalences of musculoskeletal disorders of waist (55%), back (52/5%) and neck (40%) were more than those of other parts of the body. There were significant relationships between age and back disorders, job experience and back and waist disorders, and finally, weight and shoulders and knees disorders. Conclusion: The results of this study showed the high prevalence of musculoskeletal disorders and poor work conditions. Therefore, it is necessary to prevent these problems through appropriate designing of workstations based on ergonomics principles and training workers in identifying risk factors

Assessment of attention bias in the cognitive processing of neutral and emotional words Using semantic Strop test

Objective: This aim of this study was to assessment of attention bias in the cognitive processing of neutral and emotional words, using Stroop's semantic test on students. Method: 50 students from Tabriz University were selected randomly and in addition to the demographic information, they responded to the Stroop's semantic test. Data analysis was done using descriptive statistics, independent groups T-test and paired groups T-test. Results: The mean percentages of correct responses in the sample (boys and girls) in emotional words were lower than neutral words. The mean percentage of incorrect responses in the sample in neutral and emotional words was not significant. There were significant differences in neutral and emotional words between the mean percentages of without respondent in the sample in 0/001. There were significant differences in mean percentages of responses in the sample between the neutral and emotional words in 0/005. On the one hand, there were not significant differences in mean percentages of correct responses in boys in neutral and emotional words but for the girls; there were significant differences in0/005. For both sex, there were significant differences in mean response time between neutral and emotional words in 0/001

Technical Report on the Modification of 3-Dimensional Non-contact Human Body Laser Scanner for the Measurement of Anthropometric Dimensions: Verification of its Accuracy and Precision

Introduction: Three-dimensional (3D) scanners are widely used in medicine. One of the applications of 3D scanners is the acquisition of anthropometric dimensions for ergonomics and the creation of an anthropometry data bank. The aim of this study was to evaluate the precision and accuracy of a modified 3D scanner fabricated in this study.Methods: In this work, a 3D scan of the human body was obtained using DAVID Laser Scanner software and its calibration background, a linear low-power laser, and one advanced webcam. After the 3D scans were imported to the Geomagic software, 10 anthropometric dimensions of 10 subjects were obtained. The measurements of the 3D scanner were compared to the measurements of the same dimensions by a direct anthropometric method. The precision and accuracy of the measurements of the 3D scanner were then evaluated. The obtained data were analyzed using an independent sample t test with the SPSS software.Results: The minimum and maximum measurement differences from three consecutive scans by the 3D scanner were 0.03 mm and 18 mm, respectively. The differences between the measurements by the direct anthropometry method and the 3D scanner were not statistically significant. Therefore, the accuracy of the 3D scanner is acceptable.Conclusion: Future studies will need to focus on the improvement of the scanning speed and the quality of the scanned image

A finite element analysis of the heating of power cables

The rated current of any power cable is severely affected by its capability to dissipate lost power into its surroundings. The cable may be directly buried in soil. In this case it may easily dissipate the heat into the soil. However, in some specific areas the cables are due to be installed in pipes which deteriorates the heat transfer from the cable into the surroundings. Some additional losses may also appear when metallic pipes are used. The aforementioned cases are studied in this paper and an approach to the estimation of the permissible current of a cable in each condition is proposed. Finally, the results are compared to that of an existing commercial software provided by ETSA (Electric Trust of South Australia) and the possible reasons for the minor disagreements in some cases as well as the validity of each method are discussed.Feyzi, Mohammad Reza; Parker, Anthon

Position sensorless for controlling brushless DC motor drives based on sliding mode and RLS estimators using NSGA-II algorithm optimization

This paper presents a direct torque control (DTC) technique for Brushless DC (BLDC) motors with non-sinusoidal back electromotive force. DTC has some benefits such as faster torque response and reduced torque ripple for driving the BLDC motors. Because of ignoring stator flux linkage in DTC in constant torque region, BLDC motors driving is not complicated. The Sliding mode which is robust to parameter uncertainties can be used to estimate the back-EMF and generate the torque. It is employed to estimate the back-EMF waveform in a BLDC motor using only the measurements of the stator currents. The main advantages of the proposed estimator are: it is insensitive to switching noise and no filtering is required. Due to uncertainties of BLDC motor the moment of inertia and viscous damping coefficient are online identified simultaneously using recursive least square estimator. From the identified parameters the load torque is estimated. The estimated load torque is substituted into the mechanical dynamic equation to estimate the rotor speed. A modified version of Non-Dominated Sorting Genetic Algorithm (NSGA-II) is used as an effective optimization tool for regulating the PID controller parameters of speed controller and selection of four sliding mode observer gains