One of the most important issues in designing a tax on aggregate personal income is the specification of tax rates and brakets. The purpose of this[s1] study is to design the optimal framework of personal income tax in terms of tax rates and brakets and to evaluate its effects. In doing so, Microsimulation model is used and required micro data were obtained using the Household Expenditure Survey of Iranian Statistics Center in 2017. [s2] The tax rates, income brackets, deductions, exemptions, and subsidies to low-income people have been determined in such a way that the best works are determined according to the [s3] gini coefficient and progressivity index, with the restriction of providing current amount of tax revenue for the government. The results show that by introducing the new personal income tax, while maintaining the government's tax revenues and paying a negative tax to the low-income, horizontal inequality (measured by the Gini coefficient) and vertical inequality (measured by the Progressivity Index) can be significantly improved.

The Social Security Fund, as the largest pension fund in Iran, covers about half of the country's population, and its demographic and financial status is of social, political and economic importance. In this article, an attempt has been made to examine the demographic structure and the financial balance of this fund over the next 100 years (2020-2119). For this purpose, a one percent sample of the contributors and pensioners of the Social Security Fund is selected in the base year (2019) and its demographic and financial structure is predicted using a dynamic behavioral Microsimulation model. The results show that between 2020 and 2044, the population of the pensioners will increase at a high speed,so that the number of new retirees increases from about 145, 000 in 2020 to over 605, 000 in 2044. Moreover, in 2064, the total population of pensioners will pass the population of contributors, and as a result, the fund's support ratio will fall well below a number lower than 1. On the other hand, the ratio of cash incomes to expenditres will reach about 28% in 2044 (from about 82% in 2020) and the contribution rate, which equates the incomes and expenditures of the fund, will reach about 65% (from lower than 20% in 2020). The results show that tne next two decades is a crutial window for pension policy-making in Iranian Social Security Fund. Solving this crisis requires the adoption of various parametric and structural reforms focusing on the effective period of the next two decades.

Introduction: The Social Security Organization, as the largest pension fund in Iran, has unfavorable financial and demographic situation. Many researchers and policymakers have proposed increasing the retirement age as a solution to solve this problem, which is evaluated in the present study. Method: The method used in this study is the Microsimulation model, in which a sample of 1 percent of the contributors and pensioners of the Social Security Fund is selected and the effect of increasing the official retirement age in a 100-year period (from 2019 to 2118) is investigated. Findings: The results show that if the retirement age is increased by 5 years at the beginning of the simulation period, the contribution rate required to equalize the expenditures and cash incomes of the fund in 2043 will be 56% (instead of 63% in the case of no reform) and in 2118, it will reach 118% (instead of 125%). Discussion: The lack of significant effect of increasing the retirement age on the fund's financial balance can be due to the high population of people close to retirement, the absence of a minimum retirement age for hard and arduous jobs, and the 41% share of expenses independent of retirement age. In this way, in addition to plan for increasing the retirement age, it is necessary to take other measures such as reforming the rules of retirement in hard and arduous jobs and increasing the number contributors by encouraging voluntary contribution, reducing contribution evasion and increasing the working population.

Background: Given the impact of high intake of sugar-sweetened beverages on type 2 diabetes, intervention to reduce their consumption can be a top priority for any health system. Thus, the purpose of the present study is to simulate the impact of policy options related to reduce consumption of sugar-sweetened beverages (SSBs) on the prevalence and mortality of type 2 diabetes in Iranian men and women. Methods: A discrete event simulation (DES) model was used to predict the effect of several policy options on the prevalence and death from type 2 diabetes in Azar Cohort Databases. Population age-and sex-specific prevalence and incidence rate of diagnosed diabetes were derived from the national health data. The Preventable Risk Integrated Model (PRIME) model was used for coding the input parameters of simulation using R and Python software. Results: The prevalence and mortality rate of type 2 diabetes under the scenario of reduced consumption of SSBs indicated that the highest and the lowest prevalence and mortality rates of type 2 diabetes for men and women were related to no policy condition and replacing SSBs with healthy drinks, like water, respectively. Also, the maximum “number of deaths postponed/ prevented” from type 2 diabetes was related to replacing SSBs with water (n=2015), and an integration of reformulation and applying 10% tax on SSBs (n=1872), respectively. Conclusion: Simulating the effect of different policy options on reducing the consumption of SSBs showed “replacing of SSBs with water” as the most effective policy option in Iranian setting.

Congestion is one of the problems that has bothered many countries in recent decades and has imposed huge costs on many countries. For this reason, many researchers are looking for ways to reduce congestion in transportation networks. On the other hand, it is predicted that the emergence of Automated Vehicles and Connected and Automated Vehicles can be effective in reducing congestion on the roads and increasing the capacity of the roads. For this reason, this study investigates the effect of Automated Vehicles and Connected and Automated Vehicles on the capacity of roads. In this study, a freeway network with the Merge section is used and the simulations are implemented using SUMO microscopic simulator software. In this study, to determine the driving behavior, the car following model for longitudinal movements and the lane changing model for lateral movements have been used. The Krauss car-following model and the LC2013 lane-changing model were used to determine driving behavior in this study. The simulation results show that Automated Vehicles can increase road capacity by up to 52% and Connected and Automated Vehicles can increase road capacity by up to 65%, which indicates the potential of these vehicles to increase capacity and reduce congestion. The results also show that these vehicles can have a significant impact on capacity when the presence of these vehicles on the road is significant.

Traffic simulation represents an effective tool for evaluating the suggested alternatives to enhance traffic conditions prior to their application in real sites. U-turn sections represent examples of the complicated sections that cannot be analyzed properly without applying Microsimulation approach. Recently, in Iraq, speed humps were applied in prior to the merging locations and U-turn sections to enhance traffic safety. However, the characteristics of traffic at U-turn section with the presence of speed humps have got little attention in previous literatures. This paper uses VISSIM Microsimulation model to emulate traffic movements at selected U-turn sites in the cases of with and without speed humps. Three median U-turn sites have been selected where two of these sites have speed humps prior to the turning locations. Real traffic data have been obtained from these sites using video recordings to estimate specific parameters. The developed simulation models were successfully calibrated and validated with the real data. The models have been used in testing different scenarios including the effect of having different locations/ types of speed humps and finding the capacity of U-turn sections. The results showed that closer the speeds hump to the turning location is lower the time spent for merging. The time spent values are increased with the increasing of traffic speeds at humps. Higher capacity value is obtained for the site with an auxiliary lane and speeds hump compared with the other sites.

Pricing gasoline and optimal allocation of resources have always been topics of interest for governments and experts. The increasing jump in the exchange rate has created a significant difference between the nominal and real prices of gasoline. Therefore, in the present study, a solution is proposed to narrow the existing gap by introducing a floating tax proportional to gasoline consumption, and its effect on household income distribution is examined. On the other hand, the regressive feature is a weakness of the consumption tax system that leads to undesirable effects on income distribution by imposing a higher tax burden on vulnerable classes. Therefore, the proposed scenario in this study is similar to the current pricing system and is in the form of two-tiered rates (quota-based and non-quota-based rates). The quota-based section is exempt from taxes and is similar to the past procedure, while the non-quota-based gasoline price is calculated based on individuals' consumption, considering a 5% tax for each liter of consumption exceeding the monthly quota. If the consumption increases, instead of receiving more subsidies, the higher expenses will accompany the consumer. In this regard, by using an almost ideal demand system model, the effects of implementing the proposed scenario on inequality and income distribution among urban households were studied, and categorized into four gasoline consumption groups (less than 60 liters, 60 to 80 liters, 80 to 120 liters, and more than 120 liters) during the years 2017-2020, considering some demographic variables such as household size, gender, age, marital status, employment, education, and household head's ownership of housing. Price and income elasticities were extracted, and the compensatory variation (CV) index of changes was calculated. Assuming the implementation of the proposed scenario and the constancy of prices for all commodity groups except gasoline, the household expenditure data was simulated, and inequality was calculated using the Gini coefficient. The results show that if the above-mentioned scenario is implemented by the government, assuming the constancy of prices for other commodity groups, a relative improvement in the Gini coefficient is obtained, indicating a reduction in inequality.