درخت حوزه‌های تخصصی

In recent years, the fluctuation in agricultural commodity prices in Iran is increased and thus, accurate forecasting of price change is necessary. In this article, a flexible combined method in modeling monthly prices of beef, lamb and chicken from April 2001 to March 2021, was proposed. In this new method, three different approaches namely simple averaging, discounted and shrinkage methods were effectively used to combine the forecasting outputs of three hybrid methods (MLPANN-GA, MLPANN-PSO and MLPANN-ICA) together. In implementation stage of hybrid methods, based on test and error method, the optimal MLPANN structure was found with 3/2/4–6–1 architectures and the controlling parameters are carefully assigned. The results obtained from three hybrid methods indicate that, based on the RMSE statistical index, the MLPANN-ICA method performs the best when forecasting prices for beef, lamb, and chicken. The outputs of three combination approaches show that the shrinkage method, with a parameter value of K=0.25, achieves the highest prediction accuracy when forecasting prices for these three meats. In summary, the proposed method outperforms the other three hybrid methods overall.

Environment quality and its determinants are one of the main challenges of the present and future of humanity and sustainable development is interpreted in the direction of preserving and improving the environment. In recent years, many studies have been conducted on the factors affecting environmental quality. One of the main topics that have been less considered in the related studies is the impact of governance on the quality of the environment. In this study, the impact of good governance components, including economic freedom, trade freedom, and political freedom, on the Environmental Performance Index (EPI) and its sub-indices including environmental health, ecosystem vitality, and climate change is investigated. The data required for statistical analysis are related to Middle East and North Africa region countries and Turkiye (MENAT) during 2000-2021. The panel data method was used to estimate the model and examine the relationship between the variables. The findings show that there is a positive and significant relationship between economic freedom and political freedom with the environmental performance index (EPI), and there is no significant relationship between trade freedom and EPI. </span>In addition, the study found that economic freedom had a detrimental effect on ecosystem vitality and climate change, leading to negative impacts in these areas. However, it had a positive impact on environmental health, indicating that it contributed positively to this aspect. On the other hand, political freedom was observed to have a positive effect on the vitality of the ecosystem and climate change. However, it did not have a significant impact on the overall health of the environment, suggesting that its influence was more prominent in specific areas related to ecosystem vitality and climate change. <span style="layout-grid-mode: line;" data-mce-fragment="1">The result of this research showed that economic freedom has led to more investment in the oil and gas sector of MENA countries, and therefore wastewater and gas emissions have had a negative impact on the vitality of the environment and climate change, but with the increase in production and sales of oil and Gas, per capita income of countries has increased, and environmental health has improved. Also, considering that political freedom among the MENA region has a lot of diversity, the results showed that the countries with more political freedom, through greater awareness of the society and more accountability of the governments and the establishment of environmental protection laws, had a positive impact on the environment. Of course, the environmental health index is more influenced by the economic situation and per capita production of countries and political freedom has little effect on it.