---

The characterization of memory effects in crude oil markets is an interesting issue that has attracted the attention of researchers from different disciplines, from econophysics to more classical economics. The importance of the problem relies in the fact that the departure from uncorrelated behavior would imply the presence of not-random effects which, in principle, can be exploited for arbitrage. This paper tries to contribute into the issue by estimating the memory effects by means of different parametric, semi-parametric, and non-parametric methods. In the other words, this paper provides analysis on the memory of the oil markets measured via the fractional integration parameter (d) by estimating it with various methods such as the MLE, NLS, GPH, Whittle, Lo, Hurst Exponent and Wavelet. To achieve this goal, we use the daily time series for WTI and Brent spot crude oil prices as well as 3-month futures, and further divide them into yearly subsections to obtain the historical series of memories. Results of the whittle and wavelet estimations, which are better suitted for this analysis, show no evidence of a long memory process. However, the oil price time series exhibits a nonstationary mean-reverting behaviour. Note that in this paper the behaviour of memory is our concern instead of the memory value itself. The results of memory changes trend shows that memory of international oil markets does not have an important trend change. In the other words, in our study period the efficiency of the market does not have an important decline or increase.

---

  Environmental Kuznets Curve ( EKC) theory has evolved over several decades from its initial intuitive conception to the complex theoretical models of today. Through successive steps of empirical and theoretical debate, a quadratic relationship between income and environmental degradation has been proposed, criticized, defended, and criticized again.

  Along the way, each finding have new look at the subject. Critic that is provided by Mazzanti et al. (2007) and Stern (1998) is that instead of attempting to gain insight into the underlying mechanics of an EKC theoretical foundation, there are undue focus on exploring empirical regularities among a large set of variables. These critics from opponent and supporter cause researcher to review their approach and take more concerns on details and methodology of EKC theory that make the way of theoretical works.

In this paper, a microeconomics model is provided in which household confront with decision about consumption of dirty and clean goods. It is showed that household make decision in the way that, as income increases, environment pollution rise at first and then fall when household substitute dirty goods by clean goods.

---

 

  Data envelopment analysis (DEA) estimates the relative performance of decision making units (DMUs). This paper uses the idea of the Analytical hierarchy process (AHP) method and fuzzy set theory to modify the model of DEA which can be used to evaluate the performance of business units. In this paper, a new method has been proposed for estimating the performance of DMUs with interval data and weights of data. The models proposed in previous studies have interval data or interval weights of data, so the proposed model has more flexibility than previous studies . Thus, innovation has been done theoretically and the experimental part is for testing the theory. Finally, a method is introduced for ranking the DMUs by computed performance. In order to prove the applicability of the proposed method, a case study for ranking of some Iranian automotive companies products is given. The model results indicate that the proposed model will be useful for practical problems, especially when the number of choices is limited.

---

This paper tries to model the electricity demand in Iran’s industrial sector which captures economic factors and also non-economic exogenous factors. The structural time series model (STSM) approach is employed which allows using economic theory and time series flexibility. In this approach the role of UEDT (Underlying Energy Demand Trend) including technological improvement and structural changes is modeled, therefore the income and price elasticity are estimated more accurately. The results show that the UEDT has the stochastic nature. And UEDT has a great impact on industrial energy demand during 1975-2012. So, the electricity has not been used efficiently in this sector. In the short run the estimation of the income and price elasticity are 0.42 and 0.11 respectively. The value of the cross-price elasticity of electricity demand is estimated about 0.06. It shows that natural gas substitute electricity in industrial sector, however it is small.