Showing 11 results for Khosroshahi
Volume 10, Issue 2 (Spring 2022)
Abstract
Aims: The climate change consequences are more severe in semi-arid regions in the form of drought, desertification, and dust occurrence. The purpose of this study was to investigate the effects of climatic changes on dust occurrence and sand mobility in Kermanshah province, Iran.
Materials & Methods: The meteorological stations from 1992 to 2017 were selected within Kermanshah province. The trend of climate changes was analyzed by using the Mann-Kendall model. Furthermore, the dust storm index (DSI) method was used to study the frequency and severity of dust phenomenon.
Findings: The results explored that the highest precipitation is occurred in March and November in this province. DSI index was found higher value in Islamabad, Kermanshah, and Kangavar than that other station, mainly in the west of the province, occurring in in 2008 and the lowest values were in 2010 and 2013. The average wind speed was 4.6 ms-1, while the highest winds with more than 6 ms-1 speed and dominant west and southwest directions are occurred in the western part of the province. Consequently, the annual dust rose was western. Furthermore, the highest amount of dust with 175 days occurred in Saprobe Zahab (west of the province), which was mostly related to spring and summer seasons. Lancaster index explored that the sand mobility potential was prevalent in the southwestern (along to Iraq border)
Conclusion: The dust incidence is affected by climate change. Thus, maintaining vegetation and controlling land use change is essential management approach to adapting climate change in this region.
Volume 13, Issue 1 (1-2010)
Abstract
Objective: Toxoplasma gondii is an obligate intracellular protozoan that causes Toxoplasmosis in human and animal. In recent years, significant progress has been made in the identification of vaccine candidates which can induce protective responses. In this study we used complete Rhoptry protein 2 gene of Toxoplasma gondii as a single DNA vaccine and evaluated its immune responses in comparison with control groups.
Materials and Methods: BALB/c mice were immunized intramuscularly with three weaks time interval with pcROP2 (as case group) and pc-DNA3 and PBS (as control groups). After immunization, we evaluated the immune response using cytokine and antibody measurements.
Results: The results of cytokine (IFN-γ, IL-4) assays showed that mice immunized with pcROP2, elicited stronger Th1-type cellular immune responses than those immunized with empty plasmid, or PBS (high level of IFN-γ and low-level of IL-4).Also Anti-T. gondii IgG titres (OD) increased markedly in the pcROP2 group, which was significantly higher than those of control groups (P<0.05). When challenged with the highly virulent Toxoplasma gondii RH strain, mice immunized with pcROP2 had siginificantly higher survival rates compared to control groups (P<0.05).
Conclusion: This study showed that pc-ROP2 as a single DNA vaccine is effective to prime enhanced and balanced cellular and humeral immunity responses, and relatively improved mice survival time against toxoplasmosis.
Amir Rasti, Javad Hashemi Khosroshahi, Sina Sabbaghi Shahi, Mohammad Hossein Sadeghi,
Volume 15, Issue 13 (Special Issue 2016)
Abstract
Hamed Hassanpour, Amir Rasti, Mohammad Hossein Sadeghi, Javad Hashemi Khosroshahi,
Volume 15, Issue 13 (Special Issue 2016)
Abstract
Volume 16, Issue 86 (4-2019)
Abstract
In this research, the Carum copticum essence (0.25, 0.5 %) and beta-carotene (0.015, 0.03 %) in the film containing citric pectin were used to modify and determine the functional properties of the films. The dependent variables included moisture content, thickness, water vapor permeability, antioxidant properties, color indexes and microbial properties. The results showed that adding Carum copticum essence and beta-carotene reduced the amount of moisture significantly, the lowest amount of moisture was in the film contained the highest amount of essence and beta-carotene. The thickness of the films decreased significantly with the addition of essence and beta-carotene. The water vapor permeability increased and decreased by adding essence and beta-carotene, respectively. Addition of Carum copticum essence and beta-carotene increased the antioxidant properties of the films. The lightness parameter increased in films containing Carum copticum essence. Addition of β-carotene to 0.015% reduced the amount of lightness, but at higher concentrations, the lightness increased significantly, in the other hand Yellowness index was increased by adding beta-carotene and whiteness index decreased. In terms of microbial properties of the antimicrobial effect of Carum copticum essence on B. cereus was more than E. coli. Due to the fact that the beta-carotene pigment in different conditions changes the color of food products, the films will be used in intelligent packaging of food products.
Alireza Rostamzadeh Khosroshahi, Seied Esmaeel Razavi, Seyed Mehdi Mirsajedi,
Volume 18, Issue 6 (10-2018)
Abstract
Present study proposes a new multidimensional artificially characteristic-based (MACB) scheme for simulation of combined convection flows. Multidimensional characteristic structure for energy propagation in incompressible flow is derived for the first time. Four pseudo-waves are selected and equations are discretized along them to observe the physical behavior of domain. Viscous fluxes are computed by variables derivatives at the cell interfaces and for time discretization, a 4th-order Runge-Kutta method was used. According to the new scheme, two-dimensional flow with heat transfer in a square cavity and forced convection around a circular cylinder are solved for a wide range of Reynolds and Grashof numbers. Also, for comparison purposes, the CB scheme with averaging for energy equation is used. It was found that MACB has remarkable faster convergence in comparison with CB scheme and averaging methods. Also, by using MACB scheme, maximum permissible CFL number can be increased 80 percent in comparison to CB scheme. At higher Richardson numbers, the conventional flux averaging was failed to converge properly while MACB scheme presents the most rapid convergence. The computed results of MACB scheme are in good agreement with the benchmark solutions.
Hossein Abdollahi Khosroshahi, Mohammadali Badamchizadeh,
Volume 18, Issue 9 (12-2018)
Abstract
Robotic arms are widely used for 2D desktop applications. In this paper, a new mechanism for a planar robotic arm is presented. In addition to having the benefits of both series of parallel robots, the proposed mechanism also eliminates the disadvantages of both categories. The arm made on the same side as the parallel arms has rigidity, strength and precision, and other positive features of the parallel arms, and on the other hand, like the serial arms, due to the lack of singular points inside the workspace, has a large, symmetrical and also be able to move continuously in the entire workspace. The kinematics relations for the arm are derived, and a controller based on AVR microcontroller & computer for the arm are introduced. The results indicate an improvement in arm performance and the removal of singular points from within the workspace.
M. Aligholami , A. Rostamzadeh Khosroshahi ,
Volume 19, Issue 10 (October 2019)
Abstract
The aim of this study is the modeling of the solar chimney for achieving the relation between turbine output power and geometrical parameters. In this regards, 9 different models are determined based on the variety of chimney height and diameter for investigating the effects of geometrical parameters on the turbine performance. As well as, in order to improvement of system performance, the hydrophobic surfaces were evaluated with consideration of friction reduction by verification of slip condition on walls. The k-ε turbulent model was used to modeling turbulence flow and reverse-fan model was employed for simulating the turbine. For this purpose, the extracted data from the mass flow rate and velocity changes were validated with prior studies and then were compared in different pressure jumps in order to better comprehension of the performance of the turbine. The optimization was done through the defined models and it was observed that to have a better and optimized design, the geometrical parameters should have been considered in the system design simultaneously. Meanwhile, the chimney diameter should have been paid more attention as one of the most important design parameters. Also, the precise correlation was represented to estimate the turbine output power with respect to the height and diameter of the chimney. Furthermore, based on the applying of slip condition on walls for simulating hydrophobic surfaces, shear stresses reduction was done and it was revealed that the hydrophobic surfaces could have a positive effect on the performance of SCPP up to 5 percent.
Mohammad Aliakbari, Mehran Mahboobkhah, Ghader Khosroshahi,
Volume 22, Issue 10 (October 2022)
Abstract
Parallel robots, which have several advantages over serial robots, have been one of the important industrial developments to increase the efficiency of controllable devices. Parallel structures have more suitable features such as higher rigidity, higher movement speed, non-cumulative errors and flexibility of the end-effecter pose. However, the workspace of parallel robots, compared to serial robots, faces limitations due to the existence of multiple kinematic chains, as well as the complexities related to robot control. Small size of workspace is one of the main challenges of parallel robots. Designing moving platform of a parallel robot is of the factors affecting the workspace of the robot. C4 is a four-dof parallel robot that is developed based on the three-dof Delta robot. In current study, the influence of the moving platform design on the workspace and efficiency of the robot has been investigated. After the initial overall design of the robot, three proposed modes for the moving platform have been investigated by considering the robot's kinematic parameters and robot error analysis. According to the results of the workspace and the robot efficiency analyses, the most efficient design has been selected.
Volume 23, Issue 4 (winter 2023)
Abstract
The purpose of this study is to investigate the effect of oil price shocks on the components of the Iranian labor market and the role of government capital expenditure in this field. Labor market components include job vacancies, job finding rates, inflow rates to unemployment and unemployment rates. For this purpose, the structural vector autoregressive approach over the period 2005:2- 2019:3 has been used. The results of impulse response functions show that positive oil price shocks have significant effects on model variables. However, negative oil price shocks are not significant. The positive oil price shock increase government capital expenditure, but due to the inefficiency of government investment, job vacancies decrease and the inflow rates to unemployment increase. As a result, the unemployment rate has risen in response to positive oil price shocks. The results show the Dutch disease and the asymmetric effect of oil price shocks on the labor market.
Introduction:
In addition to creating economic problems, the problem of unemployment can be the source of behavioral disorders and political tensions and can be considered a threat to the health of a society. For this reason, analyzing the labor market and knowing the factors that lead to unemployment is one of the concerns of every economy. Oil is a source of income in exporting countries and an important production factor in importing countries. Therefore, oil price shocks are expected to have an impact on market developments in terms of income and cost effects. This study aims to answer the question of whether oil price shocks have an effect on the components of Iran's labor market. For this purpose, the effect of oil price shocks from the channel of construction expenditure on the rates of finding a job, entering unemployment, unemployment and job opportunities, which are adjustment factors and represent the components of the labor market, are investigated.
Methodology:
In this article, structural vector auto regression (SVAR) model is used to investigate the effect of oil price shock on labor market components. For this purpose, it is necessary to specify the VAR model first, and then analyze the SVAR model by applying restrictions on matrices A and B. Constraints are imposed on the relationships between the regression residuals and the disturbance terms of the structural equation system so that the structural form can be identified.
Results and Discussion:
The results related to the significance of the variables show that all the variables are at the significance level. In addition, the optimal lag for estimating the basic VAR model based on the Akaike criterion is 1. Examining the roots of the VAR equation system shows that all the roots are less than one and are inside the unit circle, so the effects of shocks disappear in the long-run and the system is stable. The findings show that one standard deviation shock to the series of positive changes in oil price causes its instant increase by 0.4 and its effect decreases in the second season and disappears from the third season onwards. Government construction expenditure has increased immediately in response to shocks (one-time lag amounts), but this increase is not lasting, and it has declined in the second season, and in the third season it disappears with a slight increase in shock effects that shows a strong dependence on oil revenues. Because the only source of construction expenditure is from oil revenues, job openings have declined due to these shocks, which last until the second season. Then it increases slightly, but less than the initial negative effect, and gradually the shock effect disappears. One standard deviation shock to the series of negative oil price changes will cause it to increase by 0.1 immediately, and its effect will disappear in the third quarter. The effect of negative oil price shocks on any of the variables is not significant. However, these shocks immediately reduce government construction spending. This again shows the dependence of construction expenditure on oil revenues because at the time of the drop in oil prices, construction expenditure is decreased and allocated to current expenditure.
Conclusion:
The aim of this study was to investigate the effect of oil price shocks on the labor market. For this purpose, the effects of positive and negative shocks of oil prices on construction expenditure, job opportunities, and unemployment rates, entering unemployment and finding jobs in a SVAR model were investigated. Positive (negative) shocks in oil prices immediately increase government construction spending. This increase (decrease) is not lasting and quickly decreases (increase) and from the third season onwards, the shock effects disappear. The positive shock of oil prices has a significant effect on four components of labor market, namely job opportunities, entering unemployment, job finding rate and unemployment rate. However, negative oil price shocks are not meaningful. Therefore, oil price shocks have asymmetric effects on the labor market. The results also confirm two problems of dependence on current expenditure and Dutch disease. Because shocks only affect the short term, while construction spending is expected to improve job opportunities in the long run.
Volume 24, Issue 3 (Autumn 2024)
Abstract
Introduction
Economic development is one of the main goals of all countries, and most scientists believe that development is only accessible if there is equality. For this reason, despite the differences and contradictions in schools and societies, the issue of inequality and especially economic inequality has been always a vital concern of economists and policymakers all over the world. Meanwhile, since justice is one of the fundamental goals of Islam, Islamic economists have a more scrutinizing and much clear vision of equality. Apart from the importance of economic equality in Islam, it has a cucial role in social security systems and equality concepts as well. Takaful insurance, is a widely used Islamic model in insurance risk coverage which has fundamental differences with conventional insurance mechanisms. Takaful is cooperative, not profit oriented, and fully allined and complied with Islamic rules and regulations. This study is aiming at investigating the effect of various layers of social security system on Islamic-economic equality in the Iranian provinces during 2008-2021. GMM prediction model is applied for predicting the effect of Takaful on inequality and directing houshold religious expenses towards Takaful insurance.
Methodology
According to previous theoretical and experimental literature, economic inequality can be affected by inequality in previous years. Therefore, in this study a dynamic econometric method is used to include the lagged dependant variable as one of the explanatory variables. In general, if a variable depends on vaiables of previous periods, among other independent ones, it is better to use a dynamic panel data model. Generalized method of moments is one of the common and widely used dynamic approaches. The reason for the popularity of this method is that it is very flexible and requires only some weak assumptions. Therefore, Generalized Method of Moments (GMM) greatly solves the problems of static panel data methods related to autocorrelation, variance heterogeneity, and skewness. The reason for using this method is that, firstly, there is a possibility that the current dependent variable is affected by the lagged variables, and secondly, since one of the ways to control the endogeneity of variables is to use instrumental variable and due to the fact that it is very difficult to find such an instrument, it is possible to use lagged variables as appropriate instruments applying GMM estimator.
Findings
The results of this research indicate that the inequality of the previous period has a positive and significant relationship with current economic inequality in all three models. This means that high inequality in the previous period causes high inequality in the current period. Moreover, consistent with some studies, GDP has a positive and significant relationship with economic inequality. It means that an increase in GDP is associated with increased inequality. This result indicates that in Iran, there is no antipoverty growth. Inflation rate has also a negative relationship with inequality in all models, and this relationship is significant in two models. Following some previous studies, this result can be interpreted as the negative relationship can be caused by the fact that the inflation of luxury goods is higher than the inflation of essential goods and therefore, increased inflation is more detrimental to the rich. In addition, all three layers of social assistance, basic social insurance, and supplementary social insurance significantly reduce inequality. Meanwhile, basic social insurance has the greatest effect, and social assistance has the least effect on reducing inequality. In addition, based on the results, it can be stated that by directing houshold religious expenses towards Takaful insurance, which is an Islamic insurance and a type of basic social insurance, it is possible to reduce Islamic-Economic inequality in 2023 and 2024. The amounts of the decreases are predicted to be a minimum of 0.31 and 0.25 (Chahar Mahal and Bakhtiari) and a maximum of 5.95 and 5.91 (Markazi).
Discussion and Conclusion
According to the results, investing in all three layers of social security can lead to a reduction in inequality. Therefore, it is suggested not to ignore any layer in policymaking. Due to the greater impact of basic insurance on equality, it is thought to consider it as the basic layer of social security and focus on this layer to reduce inequality more. Managers and policymakers can also focus on Takaful as one of the basic types of insurance and help to provide Islamic-Economic equality by directing houshold religious expenses towards Takaful. Moreover, it is suggested that the governmental plans should be based on combining economic growth with improved welfare and income distribution which is one of the main goals of the Islamic economy. It is also suggested that the religious and cultural officials should create the necessary explanation and enlightenment related to Takaful and social responsibility of people. The government responsiblity in creating a foundation and guiding people to fulfill their social responsibility by strengthening and developing Zakat headquarters and communicating with social security organization should not be underestimated.
