Coupling of CFD and semiempirical methods for designing three-phase condensate separator: case study and experimental validation

This study presents an approach to determine the dimensions of three-phase separators. First, we designed different vessel configurations based on the fluid properties of an Iranian gas condensate field. We then used a comprehensive computational fluid dynamic (CFD) method for analyzing the three-phase separation phenomena. For simulation purposes, the combined volume of fluid–discrete particle method (DPM) approach was used. The discrete random walk (DRW) model was used to include the effect of arbitrary particle movement due to variations caused by turbulence. In addition, the comparison of experimental and simulated results was generated using different turbulence models, i.e., standard k–ε, standard k–ω, and Reynolds stress model. The results of numerical calculations in terms of fluid profiles, separation performance and DPM particle behavior were used to choose the optimum vessel configuration. No difference between the dimensions of the optimum vessel and the existing separator was found. Also, simulation data were compared with experimental data pertaining to a similar existing separator. A reasonable agreement between the results of numerical calculation and experimental data was observed. These results showed that the used CFD model is well capable of investigating the performance of a three-phase separator

Impact of music type on motor coordination task performance among introverted and extroverted students

Purpose. People are interested in music. In this study, we assessed the impact of music type on objective performance.Materials and methods. We distributed 64 medical science students in Tehran into four groups: Iranian pop music, traditional music, Mozart's classical music and control groups. All participants performed the two-arm coordination test once without music and once with music (except for the control group), with an interval of 1 week. In the music groups, music was playing during the performance of the test. Participants were categorized as either introverted or extroverted and were distributed equally in the groups.Results. There was a significant decrease of test time in the second trial, observed in all music groups, and no significant difference identified in the control group. The traditional music group had less difference of mean time compared to the pop music group. The differences in the traditional and classical groups were not significantly different. In the music groups, both extroverted and introverted students decreased their test time significantly after music intervention, but extroverted students decreased more.Conclusion. Listening to music would enhance the speed of performance. Music with a higher tempo, such as pop music, increased the speed more

The Relationship Between Psychosocial Work Factors, Work Stress and Computer-Related Musculoskeletal Discomforts Among Computer Users in Malaysia

Increasing numbers of workers use computer for work. So, especially among office workers, there is a high risk of musculoskeletal discomforts. This study examined the associations among 3 factors, psychosocial work factors, work stress and musculoskeletal discomforts. These associations were examined via a questionnaire survey on 30 office workers (at a university in Malaysia), whose jobs required an extensive use of computers. The questionnaire was distributed and collected daily for 20 days. While the results indicated a significant relationship among psychosocial work factors, work stress and musculoskeletal discomfort, 3 psychosocial work factors were found to be more important than others in both work stress and musculoskeletal discomfort: job demands, negative social interaction and computer-related problems. To further develop study design, it is necessary to investigate industrial and other workers who have experienced musculoskeletal discomforts and work stress

Ergonomics in Healthcare system-Human Factors models: a review article

Introduction: The healthcare system is one of the largest sectors in most countries and is a socio-technical system in which people play a preponderant role. Nowadays medical work systems are facing three major challenges: 1) Healthcare costs, 2) Quality and patient demands and 3) complexity of healthcare. These problems show the necessity of applying ergonomic models in the healthcare sector. The aim of this study was to review the practical ergonomic models in healthcare system.   Material and method: For this review article, the authors searched through ScienceDirect, PubMed, ProQuest internet databases from 2005-2014 using the following keywords: Healthcare, Ergonomics, Human factors and model.   Result: Overall, 85 articles were reviewed. By evaluating articles' titles, 30 articles related to the study subject were chosen. Then, reviewing the abstracts resulted in 15 articles and in the final step 5 full-text articles were selected which described practical models of ergonomics in healthcare: 1) SEIPS, 2) DIAL-F, 3) Extended Patient-Staff-Machine-Interaction, 4) Adapted Medical-Task and 5) Recursive Hierarchical Task-Process-Task-Model.   Conclusion: Most of the published studies emphasize on application of ergonomic models in healthcare centers since these models may reduce their problems. These ergonomics approaches support patient-centered treatment processes, user-oriented design of medical environments, efficient utilization of resources and increase motivation of clinical staff

Safety Evaluation of the Lighting at the Entrance of a Very Long Road Tunnel: A Case Study in Ilam

Background: At the entrance of a tunnel, reflection of sunlight from the surrounding environment and a lack of adequate lighting usually cause some vision problems. The purpose of this study was to perform a safety evaluation of lighting on a very long road in Ilam, Iran. Methods: The average luminance was measured using a luminance meter (model S3; Hagner, Solna, Sweden). A camera (model 108, 35-mm single-lens reflex; Yashica, Nagano, Japan) was used to take photographs of the safe stopping distance from the tunnel entrance. Equivalent luminance was determined according to the Holliday polar diagram. Results: Considering the average luminance at the tunnel entrance (116.7 cd/m(2)) and using Adrian's equation, the safe level of lighting at the entrance of the tunnel was determined to be 0.7. Conclusion: A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers' eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone. (C) 2016, Occupational Safety and Health Research Institute. Published by Elsevier

Reliability and Validity study of the NIOSH Generic Job Stress Questionnaire (GJSQ) among Firefighters in Tehran city

Introduction: currently, stress is known as one the most important issue among societies which may have positive or negative results. Stress is caused when there is not a harmony between job demands, capabilities and desires of a person. Most of the behavioral, physical and mental disorders are results of job stress. The objective of this study was Validity and Reliability analysis of NIOSH Generic Job Stress Questionnaire (GJSQ), in order to have an appropriate tool for evaluation and analysis of job stress in Iran. . Material and Method: In this study, 228 members of Tehran fire-fighting office were chosen according to categorical and clustering sampling, methodology and they completed NIOSH Generic Job Stress Questionnaire (GJSQ). For Validity and Reliability of questionnaire, 20 persons of the group were chosen for content validity analysis of the questionnaire. For Reliability analysis of the result, Cronbach alpha test and in-cluster correlation test were used. SPSS software version 18 was used for analysis of the data. . Result: The mean age of the participants was 30.8 years (SD=4.9) and the average of job tenure in fire-fighting office was 7.4 years (SD=4.8). In order to reliability analyze the questionnaire, Cronbach alpha coefficient of all influential factors was obtained more than 0.7. In-cluster correlation coefficient of the questionnaire is calculated using retesting on all influential factors. With the exception of Physical Environment and Mental Demands which were about average, all other coefficients were over 0.7, which is a very appropriate result. . Conclusion: Considering that Validity and Reliability factors of the questionnaire were be appropriate, it can be recommended that NIOSH Generic Job Stress Questionnaire (GJSQ) can be used as a Valid and Reliable questionnaire for job stress evaluation in Iran

Lighting measurement in Shemiranat health center based on EN 12464-1 European standard

Introduction: Illumination standards especially Illumination Engineering Society of North America (IESNA) and Iran lighting standards (ILS) are just based quantitative measurements. However, lighting has psychological effects and can influence quality and quantity of productivity and comfort of workers. Therefore, Illumination standards were undergone some changes. EN 12464-1 standards focus on the quality and quantity of lighting as well as the energy consumption. The aim of this study was to evaluate quality and quantity of lighting in Shemiranat health center. .Material and Method: In this study, first work tables were divided into 20×20 squares and illuminance was measured by putting HANGER S3 luxmeter sensor on the center of each square. In next stage, the luminance of each lighting source was measured from the view of observe and the average luminance of work table surface was calculated in the divide square. Furthermore, vertical, horizontal and lateral distance between observes eye and lighting source was measured. The gathered information was put in the equation and glare rate was calculated. Finally, according to the table we obtained color rendering index of lighting sources. .Result: Results of this study showed that maintained illuminance dose not mach the standards (500 lux) in any of the work station. Moreover, the glare match the standards just in less than 10 percent of the work area. Therefore, it is essential to reform the artificial lighting system and keep the maintained luminance and glare at the standard level. .Conclusion: There is a dramatic difference between the current lighting condition and the standard values. Therefore, making changes in lighting system is obviously essential

Assessing the usability of different models of hand-held mechanical pipette to determine the best type

Introduction: In Laboratory accusations a wide range of hand-held tools are used due to nature of their work. Long-term and repeated use of these tools has led the laboratory workers to suffer from upper limb disorders. The present study was designed and implemented with the aim of investigating the usability of different models of pipettes used in the laboratories of the Tehran University of Medical Sciences, employing subjective assessment methods for selecting the best pipette models.. Material and Method: This cross-sectional and analytical-descriptive study was performed among 35 laboratories employees of Tehran University of Medical Sciences. First, four models of the widely used pipettes were selected and their usability-related characteristics were investigated by a visual analog scale (VAS). Judgments concerned the usability of the pipettes done based on the criteria provided by the International Organization for Standardization 9241-11(1998) and 20282-2(2006). Data analysis was performed, using SPSS software version 22. . Result: The overall evaluation of the users in relation to the characteristics of the pipettes indicated that the highest VAS score was belonged to pipette A, C, and D, respectively. Furthermore, pipette B was selected as the most undesirable one by users. Results related to the usability criteria of pipette showed that of the four models of study pipettes, pipette A has been ranked first in two criteria (satisfaction and effectiveness). Regarding the efficiency, the first rank was for C pipette and the second rank was for pipette A. Pipette B obtained the lowest scores for all given criteria. .Conclusion: Shorter and lighter pipettes, which were designed according to ergonomic principles, had greater usability from the perspective of users and it could cause a better subjective assessment comparing to the other models

Survey of discomfort glare from the headlamps of cars widely used in Iran

Objective: On 2-lane roads, discomfort glare can cause annoyance, discomfort, inconvenience, stress, and fatigue to drivers, posing a risk of accidents. The aim of this study is to evaluate discomfort glare from the headlamps of cars widely used in Iran.Methods: The discomfort glare of new vehicles including Pride Saba model GTX, Pride Model 131SL, Samand Soren, Peugeot 405, Megane, and Peugeot Pars was examined at distances of 5 to 100m at a background luminance of 50cd/m(2) (late twilight/early dawn lighting) and 1cd/m(2) (nighttime) using Schmidt-Clausen and Bindels model and de Boer's subjective scale.Results: According to the de Boer scale, at a background luminance of 50cd/m(2), the discomfort glare for all studied vehicles was between 1.98 and 4.05 in high-beam mode and between 3.5 and 5.4 in low-beam mode. At a background luminance of 1cd/m(2), discomfort glare was between 0.41 and 2.48 in high-beam mode and between 1.93 and 3.84 in low-beam mode. In high-beam mode, the average levels of discomfort glare of these vehicles gradually increased when the distance between cars was reduced by up to about 20m. In low-beam mode, there was no discomfort glare up to a vehicle distance of 40m. In addition, at an angle of 1.15 degrees-5.73 degrees between the line of sight and light of vehicles in high-beam mode, the level of discomfort glare was increased, but at an angle of 5.73 degrees-22.9 degrees the level of discomfort glare was reduced. In low-beam mode at an angle of 2.86 degrees-22.9 degrees, the level of discomfort glare was almost identical. The results show that in high-beam mode and with a 100-m distance between vehicles as well as in low-beam mode at intervals of less than 40m between cars, discomfort glare is created.Conclusion: It can be concluded that by providing solutions such as installing road lighting system, an increase in luminance of roads, separating or widening road lanes, increasing the lateral distance between vehicles, and increasing the angle between lighted vehicles and drivers can noticeably reduce discomfort glare

XML Investigation of the effects of wind turbine noise annoyance on the sleep disturbance among workers of Manjil wind farm

Introduction: Installation of wind turbines in residential areas due to their unique sound characteristics may cause noise annoyance. Noise annoyance can increase the risk of health problems and sleep disturbance. Thus, this study was conducted to assess the effect of wind turbine noise annoyance on sleep disturbance among the Manjil wind farm workers. Material and Method: All the Manjil wind farm workers have been divided into three groups according to their noise exposure levels, including maintenance, security, and administrative workers. The equivalent A weighted noise levels were measured for each of the study working groups, using ISO 9612 standard method. Information related to the noise annoyance and sleep disturbance were determined by ISO15666 standard and the Epworth Sleepiness Scale, respectively. Data were analyzed using R software. Result: Findings of ANOVA and Kruskal-Wallis statistical tests showed that noise annoyance and sleep disturbance were statistically different among workers with various occupational, age, and work experience groups. Also, noise annoyance and sleep disturbance had a significant association in a way that regardless of the effects of other variables, it can be stated that for every one unit increase in noise annoyance, 0.26 units will be added to the amount of sleep disturbance. Conclusion: In this study, workers with more wind turbine noise annoyance had more sleep disturbance. Therefore, in addition to the direct effects of noise on sleep disturbance, it can indirectly exacerbate sleep disturbances