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The foreign direct investment is one of the economic variables that can positively affect the economic growth, but according to some researches this does not apply to some countries. These researches implicate that this lack of positive effect is due to domestic qualification of the home country. One of the essential qualifications for positive effectiveness of foreign direct investment on the economic growth is the existence of developed financial market. Therefore, in this research we intend to examine the role of financial market in the effectiveness of foreign direct investment on the economic growth. To do this we made use of the data from 57 countries in the period 1990-2005 and the econometric technique of panel data. The results show that in developed countries because of their financial market, the effect of foreign direct investment on economic growth is positive and significant whereas in developing countries this effect is not significant.

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With regard to importance of investment as an engine of economic growth many economists such as Wicksel, Keynse and Harrod believe that investment is the main source of business cycles. Hence this study specifies investment function according to a basic macroeconomic model such as Ramsey model. Application of Ramsey model can help to extend macroeconomics with micro foundations in economy of Iran and prepares new scopes for researchers. The main idea of this study is specification of investment function according to Ramsey model and its estimation by cointegration technique for period (1990:Q1-2007:Q4). The result of econometric estimation indicated a long run relationship between investment, capital stock, and shadow price of capital, installation cost of capital, capital price and terms of trade. Results showed that capital stock, shadow price of capital and terms of trade have direct effects and, installation cost of capital and capital price have inverse effect on investment.

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This study tries to examine the way housing residential investment in Iran's urban area is influenced by the shocks of oil revenues, and for that, time series data spanning the period 1991:1-2007:4 are deployed in a Dynamic Stochastic General Equilibrium (DSGE) model including households, firms producing new residential houses, and the production of other economic firms as well as oil sector. The model is based on some simplify assumptions suitable to Iran's economy characteristics as: Iran as a small economy regarding capital flows, Oil Exports and goods imports and no price stickiness in housing sector. Moreover, the allocation of resources in the economy is determined by a central planning. The Model's solution and simulation is processed through using DYNARE as a subset of MATLAB software package. The results showed that the incidence of extreme volatility in the short ‌ behavior of housing residential investment in Iran's urban area, due to shocks of oil revenues, shocks was not Persistent and quickly disappeared. This implies that Iran's economy is suffering from Dutch Disease.

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  The purpose of this paper is to analyze the effects of inflation on real investment in Iran. After briefly reviewing the investment theories and their situation in Iran, we consider the determinants of investment by using annual data (1958-2009).

  Results of the Augmented Dickey- Fuller (ADF) test indicate that all of the variables appearing in model are I(1). So, the results of the threshold regression model indicate that real GDP, the trade openness index and inflation rate can influence investment.

Results also show that the effect of inflation on investment follows an asymmetric adjustment process. The threshold level for the rate of inflation has been estimated 11.9 percent. If the annual rate of inflation exceeds this threshold level, it will have a negative impact on investment. But, if inflation remains below this level, not only the negative effect fades away but also rising prices can boost investment.

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  In this paper a new model for optimal investment in advanced manufacturing machines is proposed, using fuzzy linear programming. In the first step decision-makers determine the strategic objectives of the company and their minimum acceptable achievement levels, using fuzzy numbers. Thereafter, feasible alternatives and their degree of influence to the achievement of each objective are concluded in the form of linguistic variables. To construct the model, the degree of influence of each alternative in the achievement of the objectives are considered as technological coefficients, and the minimum level of acceptance of objectives are considered as constraints (right hand side variables). Furthermore, the mutually exclusive alternatives, the interaction between machines and the constraint of limited investment of budget are included in the model. The aim of the model is to determine the number of machines that needs to be purchased in order to maximize the present value of investment. The calculation of net present value is executed based on discount cash flow, inflation rate, interest rate, revenue and costs of each machine on a fuzzy environment. Finally by presenting an empirical illustration, the performance of this model is clarified.