Roohollah Noori, Gholamali Hoshyaripour, Khosro Ashrafi, Omran Rasti,
Volume 6, Issue 1 (5-2013)
Abstract
Backgrounds and Objectives: Precise air pollutants prediction, as the first step in facing air pollution problem, could provide helpful information for authorities in order to have appropriate actions toward this challenge. Regarding the importance of carbon monoxide (CO) in Tehran atmosphere, this study aims to introduce a suitable model for predicting this pollutant.
Materials and Method: We used the air pollutants and meteorological data of Gholhak station located in the north of Tehran these data provided 12 variables as inputs for predicting the average CO concentration of the next day. First, support vector machine (SVM) model was used for forecasting CO daily average concentration. Then, we reduced the SVM inputs to seven variables using forward selection (FS) method. Finally, the hybrid model, FS-SVM, was developed for CO daily average concentration forecasting.
Result: In the research, we used correlation coefficient to evaluate the accuracy of both SVM and FS-SVM models. Findings indicated that correlation coefficient for both models in testing step was equal (R~0.88). It means that both models have proper accuracy for predicting CO concentration. However, it is noteworthy that FS-SVM model charged fewer amounts of computational and economical costs due to fewer inputs than SVM model.
Conclusion: Results showed that although both models have relatively equal accuracy in predicting CO concentration, FS-SVM model is the superior model due to its less number of inputs and therefore, less computational burden.
M Kalhor, S Ghaleh Askari, M Bozorgi,
Volume 11, Issue 3 (12-2018)
Abstract
Background and Objective: Concentration prediction with Gaussian dispersion models is highly sensitive to meteorological data. The lack of sounding data station in developing countries may lead to large error and uncertainty in air pollution modeling results. In this paper, the effects of estimated upper air data on the model output concentration values were investigated.
Materials and Methods: AERMOD model was executed once with real upper air data and also with estimated upper air data separately. T-Student and LEVENE tests were used to evaluate the significant differences between concentrations in two modes of using actual and estimated upper air data.
Results: The results showed that large differences in concentration between the two methods. In long term modeling, there was up to 33% differences between real and estimated upper meteorological data and up to 63% differences for short term modeling. A large difference was also observed between boundary layer parameterization values in each case. The statistical analysis showed a meaningful difference (p=0.00) between the cases. The differences between ZICNV, DT/DZ, W* were 7.1%, 48%, and 19%, respectively.
Conclusion: The use of estimated upper meteorological data in comparison with measured data may lead to a large error. The AERMOD modeling results with estimated meteorological data must be expressed with appropriate uncertainties and confidence interval.
R Dehghan, S Abdolahi, M Rahimi, F Nejad Koorki, M Amini,
Volume 12, Issue 3 (12-2019)
Abstract
Background and Objective: Due to the increasing growth of urbanization, vehicles are one of the most important environmental causes of air pollution in today's world.. With the increasing problems of air pollution and its environmental consequences due to lack of compliance with standards in manufacturing cars and their fuel consumption, awareness of the exhaust of cars and its comparison with environmental protection standards and technical examination is essential for controlling and reducing air pollution. Therefore, the present study was carried out with the aim of studying and comparing the amount of CO, CO2 and HC emissions from light vehicle exhausts in the period of 1383-1389 based on technical and environmental inspection standards in Shiraz. Also, the relationship between the year of construction of the car and the amount of output of these pollutants was discussed.
Materials and Methods: In this research, the amount of exhaust emissions (carbon monoxide, carbon dioxide and uncured hydrocarbons) from the exhaust of 858 vehicles included models Peugeot 206, GLX and Pars that were referred to the technical examination center during 5 months in Shiraz between the years 1383-1389 was investigated. Also, the relationship between the year of production and the amount of output of these pollutants was studied. Data analysis was done using SPSS software and Microsoft Excel software was used for drawing graphs.
Results: The results showed that there was a significant and negative correlation between the year of manufacture of the vehicle and the reduction of CO and HC. As the year of construction increases, the amount of pollutants is decreasing. Also, this relationship was positive and significant between the year of manufacture and CO2. Also, the exhaust pollutants (CO and CO2) from the Peugeot GLX exhaust system were lower than Peugeot Pars and 206, and the lowest amount of HC was observed in Peugeot 206.
Conclusion: In general, the exhaust emissions of all three cars were at the standard Euro 2 and technical examination.
