Ali Izadi - Department of Electrical and Computer Engineering, Majlesi Branch, Islamic Azad University, Majlesi, Iran
Hamidreza Fardad - Department of Electrical and Computer Engineering, Nikabad Branch, Islamic Azad University, Nikabad, Iran

Block chain technology, known by popular crypto currencies mainly Bitcoin, is widely used in several fields, not only in the financial sector but also in the healthcare industry as well as supply chain management sectors. To produce an efficient block chain, consensus algorithms are an essential part of it. Proof of Work (POW) and Proof of Stake (POS) protocols are widely used in many block chain networks such as Bitcoin, Ethereum, and Litecoin. Block size optimization solves the trade-off between maximum revenue and becomes an alternative payment system. In this research, differential evolution algorithm was used to determine the size of the blocks. The simulation of this research has been done in MATLAB environment. In order to evaluate the proposed method, two scenarios of the number of miners and the type of request have been used. In this research, statistical criteria have been used to evaluate the proposed method. The criteria used in this research include maximum, minimum, average and standard deviation criteria. The results showed that in the scenario of the number of miners, the best answer was obtained in the case where the number of miners was equal to ۳. In the request type scenario, the dependency of the requests has been checked. In this case, requests are considered dependent and non-dependent. The results showed that in the non-dependency mode, the request processing time has decreased because in this mode the requests can be executed simultaneously with each othe. in the dependency mode, the requests have priority over each other.  In this case until the desired request is not executed, the next request cannot be executed.

Block chain technology, Bitcoin, block chain, Proof of Work, Differential evolution algorithm