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One of the very important issues in designing hand prosthesis is to consider their cover or cortex. The purpose of this research is to design a cover to have a similar behavior, as much as possible, to the human natural skin, in power transmission and deformation pattern. A layer made of Lorica®, which has similar properties to natural skin, has been added to the conventional cover which composed of three layers. Using finite element analysis Software, ANSYS V.15, the new four-layered cover has been investigated on three dimensional model of the hand prosthetics with different thickness for the outer layer, and the pattern of deformation and internal stresses in the prosthesis are measured. Optimal thickness of the outermost layer is evaluated due to stress and strain distribution and their transformation to prosthesis metallic core. The relationship between the thickness of this layer and the distribution of stress and deformation of the cover is not linear and direct and the thickness of 1.5mm shows better results among the measured values in this section. In this study, the fourth layer was added to improve the frictional and elastic properties of formerly used prosthetic covers, and its effects on stress and strain distribution in the prosthesis was investigated. It is determined that due to lack of linear correlation between the thickness and stress distribution, the optimal thickness of each layer must be selected based on design limitation like the ability of embedding tactile sensors in future for the minimum thickness.

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Introduction:
The purpose of this paper is to analyze the relationship between economic growth, energy consumption and ecological footprint in 27 developing countries and 27 developed countries during the period 1990-2018.

Methodology:
This paper analyzes the relationship between economic growth, energy consumption, and ecological footprint in 27 selected developing countries and 27 selected developed countries over a period of 1990-2018. The present model was developed according to as Akadiri et al. (2019) and Mohammad et al. (2019), which are in the form of the following three equations:
EFPit=α1+α2iEGit+α3iNRECit+α4iRECit+α5iTECit+α6iURBit+α7iFRit+α8iMRit+α9iHCit+εit                                                                        (1)
 NRECit=β1+β2iEFPit+β3iEGit+β4iURBit+β5iFDit+εit                         (2) 
 EGit=γ1+γ2iEFPit+γ3iNRECit+γ4iRECit+γ5iFDit+γ6iTOit+γ7iLit+γ8iKit+γ9iPIit+γ10iHCit+γ11iMRit+γ12iKOFEit+εit                                     (3)
The EFP is an ecological footprint index that compares the rate of resource consumption and production of human waste with the rate of resource reproduction and waste disposal by the biosphere, being defined in terms of the amount of land needed to maintain this cycle. EG is described as the economic growth. NREC is the consumption of non-renewable energy and includes energy from combustible non-renewable energy, such as oil, gas, hydrocarbons, coal, and nuclear energy. REC is the consumption of renewable energy. FD is financial development. URB is the growth rate of urbanization. TO is the degree of trade openness. L is the labor force. K is an investment. HC is human capital. FR is the fertility rate. MR is the mortality rate. PI is political instability. TEC is the technology. KOFE is the globalization of the economy. In order to analyze the relationship between the mentioned variables, the Generalized Method of Moments (Sys-GMM) was used.

Results and Discussion:
The results showed that in both groups of developed and developing countries, economic growth was correlated with energy consumption and ecological footprint index. Nonrenewable energy consumption, urbanization rate, fertility rate and mortality rate in both groups of the country had positive effects and the renewable energy, technological growth rate and human capital had negative effects on ecological footprint. Economic growth had a negative effect on the ecological footprint of developed countries and a positive effect on the ecological footprint of developing countries, which indicates that more developed countries rely on the use of renewable energy. Ecological footprint has a negative effect and economic growth, urbanization rate and financial development had positive effects on energy consumption in both groups of countries. Ecological footprint has had a negative effect on the economic growth of developed countries and a positive effect on the economic growth of developing countries. Renewable and non-renewable energy, financial development, degree of trade openness, physical capital, labor and economic globalization had positive effects and political instability and mortality rates had negative effects on economic growth in both groups.

Conclusion:
Based on the results of the research, it is suggested that countries, especially developing countries, try to create and use clean energy. High information, proper education, exchange of information with other countries to benefit from the information and advanced goods that are in line with the environment, taxation of producers who use polluting energy and granting tax exemptions and low-interest and long-term loans to producers who use clean energy will reduce the ecological footprint. Given the impact of non-renewable and renewable energy on growth and economic development, the contradiction of the impact of economic growth on the ecological footprint in developed and developing countries indicates that developed countries have adopted an approach based on which renewable energy is used rather than non-renewable energy in the production process. While the use of non-renewable energy sources in developing countries, although leading to economic growth, has led to environmental degradation. Since increasing economic growth is one of the most important economic goals of countries, it is necessary for policymakers to take measures in terms of economic growth, which imposes the least damage to the environment and achieves the goals of sustainable development. In this regard, it is recommended that the developing countries, as well as the developed countries, use renewable and less polluting energy such as solar, wind, and hydropower instead of non-renewable energy.

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Introduction:
According to the models of growth, renewable and non-renewable energy  affect economic growth, but the consumption of renewable energy due to less pollution, contributes to sustainable growth. So, countries strive to create the conditions for the use of renewable energy, such as electricity. By balancing competition in market such as the electricity market, on the micro level surplus of consumer and producer welfare is maximized without government intervention, and the incentive for the private sector to enter the market increases. On the macro level, due to lower prices and increased production, electricity consumption as renewable energy increases and reduces environmental degradation and increases sustainable growth. Over the past decades, in the electricity industry, natural monopoly conditions have been established in the sectors of production, transmission and distribution, and the surplus of consumer and producer welfare has not been maximized, so government intervention was justified. In recent years, due to technological advances and the elimination of natural monopolies, the incentive for the private sector to enter the electricity sector has been strengthened. The purpose of this article is to measure the degree of competition in 9 electricity companies in Iran during the period 2011-2019.

Methodology: 

In order to measure the degree of competition in Iran's electricity industry, two structural approaches, i.e., Entropy coefficient and non-structural Panzar-Rosse were used. 

The entropy measure is used as an alternative to variance, in fact entropy is the inverse measure of concentration, when entropy increases, concentration decreases:
E=i=1nSi.log1Si    ,    0≤E≤log⁡(n)                                                         (1)
Si  is the market share and the value of this index is equal to zero for the monopoly market and increases nonlinearly as the market becomes more competitive.
Measurement of degree of competition by Panzar-Ross method, using the GMM method is as fallows:
LnTRit=α0+α1LnQit+βLLnWLit+βKLnWKit+βELnWEit    (2)  

WLit
  is the labor input price, WKit
  is the capital input price, WEit
  is the energy input price of the power generation company i in the time period t. TRit
  is total revenue, Qit
  is production of the i-th power generation company at time t. In the dynamic specification, the Panzar-Rosse criterion for evaluating the market structure is defined as follows:

PRH=i=13βi1-α1                                                                                                       (3)
If i=13βi=1 , the market is competitive and a decrease (increase) in the price of inputs causes the same decrease (increase) in marginal cost and marginal revenue. If 0<i=13βi<1 , the market has monopolistic competition and is between competition and monopoly.

Results and Discussion:

The calculation of entropy coefficient, which is one of the structural methods in measuring competitiveness, obtained a number equal to 0.215 for the Iranian electricity industry during 2011-2019. Considering that the mentioned number is between zero and one, it shows that the concentration in Iran's electricity industry has decreased during the period under review and this industry has been placed in a state between competitive and monopoly. In other words, the conditions of the electricity industry have moved out of the traditional state and full monopoly, although it still needs to establish arrangements to become more competitive and close to full competition. On the other hand, Panzar-Rosse non-structural method was also estimated and its index was calculated, which obtained a value of 0.253. This amount of Panzar-Rosse non-structural index also confirms the results of the non-structural approach in Iran's electricity industry. Due to the fact that the results of both structural and non-structural approaches in calculating the level of competitiveness in Iran's electricity industry confirm each other, more confidence is created regarding the obtained result.

Conclusion: 

Considering the important and effective role of electricity in other industries of the country, the existence of more competition that leads to a decrease in the price and increase in the production of electricity, from a micro point of view, it has led to an increase in consumer and producer surplus, and from a macro point of view, it has also led to a reduction in environmental pollution. Reducing the exploitation of non-renewable energies and as a result of intergenerational justice and ultimately the realization of sustainable growth and development. Although the results of the calculation of competitiveness indicators indicate that the electricity industry is moving away from the monopoly state and moving towards the competitive state, more efforts should be made in order to increase the degree of competition and achieve complete competition in the country.

 In this way, the country's economic managers and policy makers should increase the number of power plants in Iran's electricity network while removing the existing legal obstacles on the path of restructuring from monopoly to full competition in the country's electricity industry in order to reduce the level of concentration and monopoly in Iran's electricity market. On the other hand, creating a suitable environment for the correct and healthy competition of electricity companies, improving the productivity of production inputs and using the optimal combination of inputs through research and development, as well as short-term and long-term planning to improve the level of production and improve the cost structure, and encouraging and supporting elites and inventors in line with the development of new electricity production plans and technologies such as solar electricity technology can help to make the structure of the electricity industry more competitive.

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