Blockchain technology originated from virtual currency, which, since 2009, has sprung up all over the world and has gradually entered people's sight. Blockchain is a new integrated application model of distributed data storage, point-to-point transmission, consensus mechanism, cryptographic algorithm and other computer technologies. In a broad sense, blockchain technology is a new distributed infrastructure and computing method by using blockchain data structure to verify and store data, distributed node consensus algorithm to generate and update data, cryptography to ensure the security of data transmission and access, and intelligent contract composed of automatic script code to program and operate data.

Blockchain has the characteristics of decentralization, openness, independence, security and anonymity, including the core technologies of distributed ledger, asymmetric encryption, consensus mechanism and smart contract. With its distinctive advantages, blockchain technology is positioned to play an important role in innovative industry applications and the improvement of social governance. Governments, industry and academia all over the world have been paying close attention to the applications and developments of blockchain technology. Relevant technological and model innovations continue to emerge. Typical application fields of blockchain technology include finance, internet of things, logistics, public service, digital copyright, insurance, public welfare, among many others.

In order to discuss the latest research progress of blockchain technology, theory and applications, Journal of Systems Science and Information (JSSI) publishes this special issue, which selected eight latest research papers on development, theory and applications of blockchain technology in different fields, including one review article, three theoretical discussion articles and four papers on blockchain application scenarios. We will classify and review blockchain technology related studies from the above three aspects as follows

1) Overview of blockchain technology and application: Wang, et al. investigated the research status of blockchain-related studies and analyze the development and evolution of this latest hot area via bibliometric analysis in "A Systematic Overview of Blockchain Research". This research delivers a holistic picture of blockchain research, illuminates the future direction of research, and most importantly provides implications for both academic research as well as enterprise practice.

2) Blockchain technology related theoretical research: In "Research on Distributed Data Sharing System based on Internet of Things and Blockchain", Sun, et al. proposed a distributed data sharing system architecture based on the Internet of Things and blockchain technology. In this system, the distributed consensus mechanism of blockchain and the distributed storage technology are employed to manage the access and storage of Internet of Things data in a secure manner. A computing power allocation game in blockchain-backed cryptocurrency networks is addressed in "A Hashing Power Allocation Game with and without Risk-free Asset", where Cheng, et al. considered two settings of the game, depending on whether each miner can allocate their fund to a risk-free asset or not, and show that this game admits unique pure Nash equilibrium in closed-form for both settings. Cheng, et al. discussed the block withholding attack in a mining pool and establish an evolutionary game model to study the behavior tendency of the miners and the evolutionary stable strategies under different conditions, by formulating the replicator dynamic equations in "The Evolutionary Equilibrium of Block Withholding Attack".

3) Application scenarios of blockchain technology: Liu, et al. analyzed the impact of blockchain technology on the port supply chain and the technology sharing on the shipping market in "Blockchain Technology Investment and Sharing Strategy of Port Supply Chain under Competitive Environment". When the efficiency of technology investment and the proportion of market expansion reach a certain combination, there are two different equilibrium strategy choices: Only technology investment or technology sharing. Li, et al. proposed a human resource management mechanism based on blockchain technology in order to make the company's human resource management system more accurate, efficient, open and transparent. This paper provides the application scenarios of blockchain technology in human resource management system. Hoffmann proposes a robust and scalable blockchain technology with proof of stake and limited energy consumption to streamline banks' processes, resulting in lower transaction and administration costs by smart contracts in "Blockchain Use Cases Revisited: Micro-Lending Solutions for Retail Banking and Financial Inclusion". This facilitates small scale lending at high frequencies and short-term durations as well as an easier and more efficient way to connect small borrowers and lenders. Hu, et al. studied the benefits of the blockchain food traceability system (BFTS) in "Blockchain or not? Optimal Decisions for Food Retailers considering Consumer Expertise". By comparing the optimal total welfare under the BFTS and that under the traditional food traceability system (TFTS) in valuation analysis, conditions are established on when applying the BFTS is more valuable than applying the TFTS.

Donglei DU, Jian LI, Yongwu LI

May 6, 2021