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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Physical Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Response surface methodology,Bitumen,Ash removal,Pyrite sulphur removal,Column Flotation process
- چکیده:
- چکیده انگلیسی: An efficient method was employed for the ash and pyrite sulphur removal from bitumen using column flotation process. The bitumen samples containing 9.6% sulphur (6.81% in the pyrite sulphur form) and 26.4% ash were successfully showed up to 75.20% of pyrite sulphur (e.g.; 51.66% of total sulphur) and 70.81% of ash removal. The Box-Behnken Design (BBD) was employed to design the experiments, to optimize and evaluate the individual and interactive effects of six effective independent factors: the amounts of collector and frother agents, solid weight percentage in the pulp, particle size, wash water rate and feed rate. In order to investigate system a laboratory scale rig was built. In all experiments, pine oil and kerosene were considered as frother and collector agents, respectively. The best result for column flotation process were amount of collector (1.5 kg/tbitumen), amount of frother (0.3 ppm), pulp content (10% of solid), particle size (100 mesh), wash water rate (0.4 L/min), feed rate (1.5 L/min) and flotation time (10 min). The coefficient of determination, R2, showed that the RSM model can specify the variations with the accuracy of 0.924 and 0.938 for the percentage of ash and pyrite sulphur removal from bitumen, respectively.
- انتشار مقاله: 22-05-1395
- نویسندگان: Yasser Vasseghian,Mojtaba Ahmadi,Mohammad Joshaghani
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Particle Science & Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Response surface methodology,Bitumen,Ash removal,Pyrite sulphur removal,Column Flotation process
- چکیده:
- چکیده انگلیسی: This study investigates removing ash and pyrite sulphur from bitumen by column flotation process. Central composite design (CCD) of response surface methodology (RSM) was applied for modeling and optimization of the percentage of ash and pyrite sulphur removal from bitumen. The effects of five parameters namely the amounts of collector and frother agents, particle size, wash water rate and feed rate on percentage of ash and pyrite sulphur removal from bitumen were investigated. The used bitumen sample has 26.4% ash and sulphur content of 9.6% (6.81% in the pyrite sulphur form). All the tests were carried out under aeration rate of 4L/min and pulp containing 5% of solid using pine oil and kerosene as frother and collector agents, respectively. The coefficient of determination, R2, showed that the RSM model can specify the variations with the accuracy of 0.971 and 0.975 for ash and pyrite sulphur removal from bitumen, respectively, thus ensuring a satisfactory adjustment of the model with the experimental data. The RSM was used to optimize the process conditions, which showed that initial amount of collector of 2.00kg/tbitumen, amount of frother of 0.2ppm, particle size of 101.29mesh, wash water rate of 0.5L/min and feed rate 1.26L/min were the best conditions. Under the optimized conditions, the maximum percentage of ash and pyrite sulphur removal from bitumen was 88.74% and 90.89%, respectively.
- انتشار مقاله: 21-02-1395
- نویسندگان: Yasser Vasseghian,Mojtaba Ahmadi,Mohammad Joshaghani
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Health Sciences and Surveillance System
- نوع مقاله: Journal Article
- کلمات کلیدی: Safety Climate,Perceived stress,Workers,Tile industry
- چکیده:
- چکیده انگلیسی: Background: Occupational health and safety is important for workers and their employers. Unfavorable safety climate can affect the workers' health and performance negatively. Job stress is a harmful pheromone in the industries that have been a concerning issue in recent years. This study aimed to determine the safety climate and its effect on the workers' perceived stress in a tile industry in the west of Iran.
Methods: This cross-sectional study was conducted on 135 employees working in a tile industry in the west of Iran in 2018. The data were collected using demographic characteristics, safety climate, and Cohen's perceived stress questionnaires. Data were analyzed by descriptive statistics, Spearman’s correlation coefficient, and leaner regression test using SPSS version 22 software.
Results: The mean (SD) of safety climate was 3.06±0.55 (out of 5) and that of perceived stress was 26 ±8.22 (out of 56). A significant inverse relationship was found between safety climate and perceived stress (r=-0.240, p-value= 0.005). Safety climate was not significantly correlated with demographic features and background factors (p-value > 0.05).
Conclusion: The results of this study showed that the level of safety climate was moderate to high; besides, the unfavorable safety climate can be a risk factor for perceived stress. Given the inverse relationship between safety climate and perceived stress, improving the staff's safety level by engineering and managerial interventions can be useful in improving the workers' health.- انتشار مقاله: 03-08-1399
- نویسندگان: Ehsan Bakhshi,Mojtaba Ahmadi,Reza Kalantari
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Advances in Computer Engineering and Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Neural network,nonlinear system identification,Hammerstein-Wiener model,state space and subspace identification
- چکیده:
- چکیده انگلیسی: Neural networks are applicable in identification systems
from input-output data. In this report, we analyze the
Hammerstein-Wiener models and identify them. The
Hammerstein-Wiener systems are the simplest type of block oriented
nonlinear systems where the linear dynamic block is
sandwiched in between two static nonlinear blocks, which
appear in many engineering applications; the aim of nonlinear
system identification by Hammerstein-Wiener neural network
is finding model order, state matrices and system matrices. We
propose a robust approach for identifying the nonlinear system
by neural network and subspace algorithms. The subspace
algorithms are mathematically well-established and noniterative
identification process. The use of subspace algorithm
makes it possible to directly obtain the state space model.
Moreover the order of state space model is achieved using
subspace algorithm. Consequently, by applying the proposed
algorithm, the mean squared error decreases to 0.01 which is
less than the results obtained using most approaches in the
literature.- انتشار مقاله: 22-10-1393
- نویسندگان: Maryam Ashtari Mahini,Mohammad Teshnehlab,Mojtaba Ahmadieh Khanehsar
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Applied Research in Water and Wastewater
- نوع مقاله: Journal Article
- کلمات کلیدی:
- چکیده:
- چکیده انگلیسی:
- انتشار مقاله: 16-07-1395
- نویسندگان: Mojtaba Ahmadi,Pegah Amiri
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Chemistry and Chemical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Carbon nanotubes,PMMA,Nanocomposites,Supercritical carbon dioxide,Microcellular foam
- چکیده:
- چکیده انگلیسی: Nanocomposites containing poly(methyl methacrylate) (PMMA) and surface functionalized Multi-Walled Carbon Nanotubes (MWNTs) were synthesized. The dispersion of MWNTs in PMMA was characterized using Transmission Electron Microscopy (TEM).The synthesized nanocomposites were successfully foamed using a simple method based on the in-situ generation of supercritical carbon dioxide (CO2). This method in contrast with conventional methods exempted from high-pressure pump and separated CO2 tank. The effect of MWNTs concentration, saturation temperature and saturation pressure on cellular morphology of the prepared microcellular foams were studied by Scanning Electron Microscopy (SEM), and average cell size and cell density of the prepared foams were studied by image analysis. An increase in cell density, as well as a reduction of cell size, was observed with an increase in the concentration of carbon nanotubes. It was also observed that an elevation of saturation temperature from 90 °C to 100 °C, at constant saturation pressure, leads to a higher cell density and a lower average cell size. Furthermore, an increase in saturation pressure results in a decrease in average cell diameter as well as an increase in cell density. However, the effects of MWNTs concentration on both of average cell size and cell density were proved to be more striking than those of saturation pressure.
- انتشار مقاله: 26-07-1394
- نویسندگان: Mojtaba Ahmadi,Reza Jahanmardi,Mahdi Mohammadizade
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Advanced Biological and Biomedical Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Iran,Epidemiology,Lorestan,Echinococcosis
- چکیده:
- چکیده انگلیسی: The aim of this study was to determine the prevalence of hydatidosis in Lorestan province during a 10 year period (2005-2014). We surveyed medical records of infected patients with hydatid cyst who had been operated in referral hospitals of Lorestan province, Iran. Several parameters were analyzed including age, gender, place of residency, hospitalization time, and the location of cysts. Cystic Echinococcosis (CE) affected more males 114 (52.52%) than females 84 (47.47%). The age of the patients ranged from 3 to 76 years, and the age group 20– 30 years (27%) was the most affected. Cysts were localized in liver and lung in 62.63% and 37.37% of cases respectively and unusual cyst locations in kidneys, brain, pelvic area, spleen and spine was not observed. The average hospitalization time was 7 days. The distribution of residence in patients showed 124 (62.63%) of them to have urban origin and 74 (37.37%) were rural residents. Significant relationships were found between gender and cyst location, and place of residency and cyst location (p<0.05). Single organ involvement was found in 80% of the patients, and was more common in males (51.25%) than in females (48.75%). Farmers had the highest rate of infection (19.19%) followed by students with 18.69%. Because of the growing trend of hydatid cyst operation in Lorestan province, which may be due to many different reasons further studies are needed for evaluation of economic burden and risk factors for CE in this region.
- انتشار مقاله: 07-10-1394
- نویسندگان: Mojtaba Ahmadinejad,Zia Obeidavi,Asghar Aaliehpour,Behrouz Beiranvand,Elham Sheikhi,Mehdi Babaei,Simin Babaei
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Advanced Studies in Humanities and Social Science
- نوع مقاله: Journal Article
- کلمات کلیدی: Infertility,income,Happiness,Spiritual intelligence,life satisfaction
- چکیده:
- چکیده انگلیسی: Infertility could be considered as one of the diseases which cause many psychological problems such as low level of happiness. Beside the direct effects of infertility, other factors could affect the happiness level of the infertile women. This study was conducted to investigate these factors. In this descriptive-analytic study, a total of 130 women who visited our center in Kermanshah, Iran, were selected by using convenience sampling method. Demographic data questionnaire, the Spiritual Intelligence Self‐Report Inventory (sisri-24), Oxford happiness inventory (OHI) and Satisfaction with life scale (SWLS) were used to collect the data. In this study, the mean score for happiness level of the infertile women was found to be 30.98. The results, also, showed that there is a positive significant correlation between happiness with income, wife and the husband’s education level, life satisfaction and spiritual intelligence and its three subscales. Moreover, a significant but negative correlation was found to exist between the length of the infertility period and the happiness level of these women. Finally, the education level factor was found to be the most effective in predicting the happiness level of the infertile women. based on the findings of this study, the happiness level of the infertile women was lower than the rest of the population within the society. Considering the fact that some factors affects the happiness level of these people; therefore, interventions which could target these factors could increase these women’s happiness level.
- انتشار مقاله: 12-12-1397
- نویسندگان: Seyed Teymur Seyedi Asl,Mitra Bakhtiari,Amir Raufi,Vida Yousefi,Mahtab Poursalman,Seyed Mojtaba Ahmadi
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Environmental Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: optimization,Potassium peroxydisulfate,Blue dye,Response surface methodolog,Color removal
- چکیده:
- چکیده انگلیسی: The optimization of process conditions for the degradation of Acid Blue 193 by UV/peroxydisulfate was investigated using response surface methodology (RSM). The effects of four parameters namely initial K2S2O8 concentration, UV irradiation, temperature, and initial dye concentration on two process responses, color removal and the rate constants of the first-order kinetic equations, were investigated using a second-order polynomial multiple regression model. The analysis of variance (ANOVA) explained a high determination coefficient (R2) value of 0.927-0.967, which ensures a good fit of the first-order regression model with the experimental data. The central composite design (CCD) was used to optimize the process conditions, which showed that an initial K2S2O8 concentration of 5 mM, UV irradiation of 250 W, temperature of 50 °C, and the initial dye concentration of 40 mg/L were the best conditions. Under optimum conditions, the maximum color removal from the wastewater and the rate constants of the first-order kinetic equation were 100% and 0.086 min--1, respectively.
- انتشار مقاله: 09-09-1378
- نویسندگان: Mojtaba Ahmadi,M. Hamed Ardakani,A.A Zinati Zadeh
- مشاهده