【Abstract】With the success of Bitcoin, nowadays, both academia and industry have been focusing on the expansion of blockchain in non-cryptocurrency applications to facilitate the development of Industry 4.0. The incentive mechanism in blockchain, which encourages miners to participate in validation processes, is important to the maintenance of the system. However, the techniques, which are widely applied in existing blockchain systems, are not suitable for non-cryptocurrency applications with business models and have become a major issue that undermines the adoption of blockchain. In this paper, we propose a compatible incentive mechanism for non-cryptocurrency applications to encourage validators' actions to align with consensus algorithm. The compatible incentive mechanism works with a consensus algorithm to make the blockchain technology more adaptable in industry applications. The proposed design matches with the voting-based Practical Byzantine Fault Tolerance (PBFT) consensus algorithm which is adopted by most non-cryptocurrency applications. Game theory-based analysis is conducted to identify the problems caused by participants' misbehaviours. Meanwhile, a mechanism design based on game theory analysis is adopted to develop our incentive mechanism which satisfies the compatibility requirement. Both mathematical proof and simulation experiments are used to evaluate our mechanism design. The results demonstrate that our compatible incentive mechanism encourages the desired honest behaviour among validators so that the blockchain can be maintained to align with the consensus algorithm.
【Abstract】Electric power systems are transitioning towards a decentralized paradigm with the engagement of active prosumers (both producers and consumers) through using distributed multi-energy sources. This paper proposes a novel Blockchain based peer-to-peer trading architecture which integrates negotiation-based auction and pricing mechanisms in local electricity markets, through automating, standardizing, and self-enforcing trading procedures using smart contracts. The negotiation of the volume and price of the peer-to-peer electricity trading among prosumers is modeled as a cooperative game, and the interaction between a retailer and its ensemble of prosumers is modeled as a Stackelberg game. The flexibility provision from residential heating systems is incorporated into the energy scheduling of prosumers. Case studies demonstrate that the proposed architecture in local electricity markets helps improve local energy balance. Flexibility from the residential heating systems enables prosumers to be more responsive to the variation of retail electricity prices. The proposed model reduces 41.24% of average daily electricity costs for individual prosumers or consumers compared to the case without the peer-to-peer electricity trading.
【Abstract】The blockchain technology in the Internet of Vehicles (IoV) can be applied to solve security problems. Due to the high dynamics and resource constraints of the IoV, the traditional single-chain blockchain system is not suitable for the practical scenarios. In our previous work, we proposed a lightweight blockchain architecture based on the directed acyclic graph lattice (DAG-lattice) structure for the IoV. However, the current consensus algorithms are not suitable for the previous architecture mentioned above. Therefore, this article proposes a parallel consensus mechanism based on the DAG-lattice structure in the IoV using practical Byzantine fault tolerance (PBFT) as consensus algorithm. This mechanism solves the problem of low efficiency of PBFT caused by too many consensus nodes and the mobility of nodes by adopting the method of network sharding, and meanwhile to ensure that transactions can be reached on consensus parallelly. To avoid the selection of primary nodes from being predicted in advance, this article proposes a primary node selection method based on verifiable random function (VRF). Moreover, a method is proposed of selecting transactions based on weighted round robin (WRR) scheduling to motivate nodes for the purpose of maintaining a high reputation score. Finally, the performance of the proposed scheme is verified by experiments whose results show that the proposed consensus mechanism shows better performance than other comparable schemes in terms of the time added to the blockchain, transaction per second (TPS), consensus success rate, and the time of obtaining transaction. And the proposed mechanism is less dependent on roadside unit (RSU).
【Abstract】Blockchain is a distributed ledger in which participating users with varying levels of trust agree on the ledger's content using a consensus mechanism called consensus protocols. There has been a rising interest in the design of consensus protocols since they play a central role in blockchain architecture. However, many recently proposed consensus protocols lack experimental verification which hampers the possible deployment of these protocols in real-world blockchain networks. In this article, we propose a simple tool called simplified consensus protocol simulator (SIM-P) that can accurately simulate the behavior of these consensus protocols with ease. It is an agent-based stochastic simulator that relies on the sequential Monte Carlo method to model how block publishers are selected. The likelihood of each node (represented as agents) being selected as a block publisher is represented by independent trials in a binomial experiment. We provide a base SIM-P model that simulates Proof of Work (PoW) for benchmarking purposes. The PoW model also serves as the basic structure of the simulator that can be adapted to other protocols. We showcase the flexibility of SIM-P by proposing two additional simulation models for Proof of Reputation-X and Proof of Contribution, both of which lack experimental verification in their original design specifications. We show how the simulator can be used to produce vital metrics, such as throughput, resistance against the 51% attack, and energy consumption. We verify the accuracy of SIM-P by comparing PoW's simulated results with theoretical estimates and historical Bitcoin data.
【Keywords】Consensus protocol; Protocols; Bitcoin; Peer-to-peer computing; Adaptation models; Stochastic processes; Internet of Things; Blockchain; consensus protocol; proof of contribution; proof of reputation; Proof of Work (PoW); simulator
【Abstract】In this article, I extend the modalities of mental health integration to the metaverse further toward the alternative case of museums. Some countries have modeled health facilitations of psychological nature to museums either physically or virtually. The metaverse as the incorporation of digital and actual bodies poses a further philosophical question of addressing the network of institutional and personal somatic modifications in the post-COVID-19 era.
【Abstract】As an important form of education in the future, Edu-Metaverse cannot only innovate the existing teaching mode, provide diversified teaching resources and environments, realize intelligent teaching evaluation and certification methods, etc., but also realize the real integration of people's physical world and virtual world. Therefore, how to deepen the concept of metaverse into the field of education and creating an innovative education model has become the challenge of this research. To this end, this paper develops a comprehensive Edu-Metaverse ecosystem architecture which provides an effective implementation reference for the development of the Edu-Metaverse. In addition, the Edu-Metaverse teaching mode is constructed, and the feasibility of the Edu-Metaverse teaching mode and its breakthrough significance to the existing offline and online education are demonstrated through questionnaires. Through the case study of Edu-Metaverse teaching, the implementation scheme and effective ways of Edu-Metaverse are verified. The research shows that Edu-Metaverse can not only broaden and deepen the educational content, but also reduce the educational cost and improve the quality and efficiency of education, but it also has potential risks.
【Abstract】GaN-based Micro-LED has become a research hotspot as a novel display technology due to its numerous unique advantages. Especially in augmented reality and smart glasses applications, Micro-LED display chip with high transparency possesses unparalleled opportunities. In this work, GaN-based transparent single-color Micro-LED display chip based on double-side polished sapphire substrate was designed with a singlepixel size of 20 mu m x 20 mu m, and a resolution of 254 pixel per inch (PPI). The transparency reaches 80% among the whole display area similar to 0.18 inch, and the luminance of display chip can reach up to 25000 nits. It demonstratesa broad application prospects in augmented reality, smart glasses, and etc., providing promising vista for the development of "Metaverse" in the future.
【Abstract】In the set reconciliation problem, remote parties seek to reconcile similar sets of data according to an efficiency objec-tive, such as minimizing communication or computation. Though investigated for many individual distributed applications, this problem still lacks a holistic treatment, and this is the aim of this work. Specifically, we design and analyze GenSync, a unified set reconciliation framework that incorporates several state-of-the-art set reconciliation protocols with an integrated testbed. We compare and analyze the various protocols and offer general guidelines for selecting a good protocol for a given applica-tion. Through extensive experiments, we demonstrate that the optimal choice of protocol is highly sensitive to several parame-ters, including network properties (e.g., bandwidth and latency) and computing power. Notably, none of our framework's pro-tocols are universally dominant under diverse conditions, and a poor protocol choice may lead to a 5x hit in performance. To demonstrate our framework, we measure the effects of protocol choice in reconciling memory pools of adjacent Bitcoin nodes.
【Abstract】In this paper, a trusted multi-task distri-bution mechanism for Internet of Vehicles based on smart contract is proposed to improve the security and efficiency for the task distribution in Internet of Vehi-cles. Firstly, a three-tier trusted multi-task distribution framework is presented based on smart contract. The smart contract will be triggered by the task request. As the important part of the smart contract, the task distribution algorithm is stored on the blockchain and run automatically. In the process of the task distribu-tion, the cost of the task distribution and the system stability play a critical role. Therefore, the task dis-tribution problem is formulated to minimize the cost of the task distribution whilst maintaining the stability of the system based on Lyapunov theorem. Unfortu-nately, this problem is a mixed integer nonlinear pro-gramming problem with NP-hard characteristics. To tackle this, the optimization problem is decomposed into two sub problems of computing resource alloca-tion and task distribution decision, and an effective task distribution algorithm is proposed. Simulation re-sults show that the proposed algorithm can effectively improves system performance.
【Abstract】Consumer knowledge of the goods produced or processed by the numerous suppliers and processors is still relatively low due to the growing complexity of the structure of pharmaceutical supply chains. Information asymmetry in the pharmaceutical sector has an effect on welfare, sustainability, and health. (1) Background: In this respect, we wanted to develop a productive structure for a pharmaceutical supply chain that satisfies the consumer information needs and fosters consumer confidence in the pharmacy goods they buy. By using blockchain technology, the main goals were to develop and implement a pharmaceutical supply chain. (2) Objectives: The main objectives of this work were to leverage an Ethereum platform for the development of a tractability system in a pharmaceutical supply chain environment and to analyze the efficiency of MSMAChain with respect to the cost and execution of transactions based on our designed smart contracts. (3) Results: This research looked into a variety of issues related to the value, viability, and effects of blockchain technology for use in supply chain applications. The methods and creations in this environment were monitored and researched. It is vital to identify a number of crucial subjects including future research areas, in order to achieve the widespread acceptance of the supply chain traceability provided by blockchain technology. (4) Conclusions: MSMAChain, an Ethereum blockchain-based approach, leverages smart contracts and decentralized off-chain storage for efficient product traceability in terms of the cost and execution of transaction for a health care supply chain.
【Abstract】Metaverse is the buzz technology of the moment raising attention both from academia and industry. Many stakeholders are considering an extension of their existing applications into the metaverse environment for more usability. The healthcare industry is gradually making use of the metaverse to improve quality of service and enhance living conditions. In this paper, we focus on the potential of digital anti-aging healthcare in the metaverse environment. We show how we can use metaverse environment to enhance healthcare service quality and increase the life expectancy of patients through more confident processes, such as chronic disease management, fitness, and mental health control, in the metaverse. The convergence of artificial intelligence (AI), blockchain (BC), Internet of Things (IoT), immersive technologies, and digital twin in the metaverse environment presents new scopes for the healthcare industry. By leveraging these technologies, healthcare providers can improve patient outcomes, reduce healthcare costs, and create new healthcare experiences for a better life, thus facilitating the anti-aging process. AI can be used to analyze large-scale medical data and make personalized treatment plans, while blockchain can create a secure and transparent healthcare data ecosystem. As for IoT devices, they collect real-time data from patients, which is necessary for treatment. Together, these technologies can transform the healthcare industry and improve the lives of patients worldwide. The suggestions highlighted in this paper are worthy to undergo implementation and create more benefits that will promote a digital anti-aging process for its users for a longer life experience.
【Abstract】Internet of medical things (IoMT) enable physicians to provide precise care on the Internet for registered patients anywhere, bringing convenience to people's everyday life. Considering the importance of patient's privacy in IoMT, data security between patients and medical servers should be protected. Therefore, the authentication of identity and the agreement of a shared secret key are particularly important. In this work, we propose a lightweight anonymous authentication scheme between patients and medical servers in IoMT. We combine blockchain technology with biometric technology in order to form a shared session secret key. It can protect the privacy of patients through mutual authentication between patients and servers. Afterwards, the formal analysis of BAN logic shows that our scheme is secure. Non-formal analysis shows that our scheme achieves designed security objectives. Finally, comprehensive comparative experiments show that our proposed scheme achieves a better performance in both computation and communication efficiency.
【Abstract】The metaverse holds a prominent place in debates over the future direction of digital networks. Proponents claim that advances in virtual and augmented reality will shape every facet of social life. This article defines the metaverse, explores the state of the technology, and addresses its public policy significance. It makes use of a political economic perspective focusing on the concepts of commodification and spatialisation. Specifically, it considers how major platform and gaming companies plan to use the metaverse to expand market share. The article also addresses the cultural dimensions of the metaverse as the latest in a series of utopian visions of a digital sublime. It proceeds to take up the social problems associated with the metaverse and concludes by describing the essential policy principles that should guide public authorities in the regulating the metaverse. These principles include acknowledging that current concerns over implementation do not limit future deployment. Moreover, public policy should start by recognising that the metaverse is a public space and not the private property of the major platforms. Finally, policy must address specific social problems deepened by the arrival of the metaverse including crime, privacy, the impact on climate, and data ownership.
【Abstract】The continued proliferation of renewable energy sources (RES) in the residential sector enables private households to increasingly participate in the energy market. However, it also poses an infrastructural challenge as their spatial dispersion and the simultaneity of their energy generation increase the strain on the main grid. Local energy markets (LEMs) have been proposed to amend this effect by leveraging market dynamics to efficiently allocate privately generated energy in the immediate vicinity. Blockchain has been suggested as suitable information technology to reflect and support the decentralization and the parity characteristic of such LEMs. While some research on the topic has been conducted, concerns regarding anonymity in the proposed markets remain. In this study, we hence conceptualize a Blockchain-based LEM which expands on previous designs by introducing a one-time-address-based anonymization technique. The proposed concept also extends the double auction mechanisms of existing LEMs by a sealed offering protocol, providing information symmetry. The concept is prototypically implemented and validated using a Proof of Authority Ethereum network. It is shown that the implementation is sufficiently scalable for proposed LEM sizes.
【Abstract】Blockchain and Internet of Things (IoT) have become one of the most researched topics in recent years. The application areas of both these fields are quite broad and one can complement the other in bringing in the best possible outcome. Keeping that in mind, this paper proposed how Blockchain can be utilized to provide a more secure and improved IoT ecosystem where the components of the ecosystem will be more protected and less susceptible to unwanted intrusions. We also considered using InterPlanetary File System (IPFS) and Hyperledger Fabric as a means of IoT data storage, which can ensure better protection compared to centralized cloud storage. We have also utilized Ethereum Smart Contracts (SC) for Proof of Concept deployment of our model. The experimental outcome as well as the cost and security analysis of our deployed Smart Contracts suggest that it is more beneficial to use Blockchain and distributed storage systems to safeguard the IoT ecosystem and its data.
【Abstract】For reasons of energy security, affordability and environment, the foundations of our energy markets are in flux. A promising approach for addressing some of the challenges faced comes in the form of blockchain-based peer-to-peer (P2P) microgrids, which we argue are a potential solution to many of the pitfalls of existing grid architectures. More specifically, this paper analyses consensus mechanisms that could be employed in blockchain-based microgrids, demonstrating that proof of authority (PoA) is a promising direction when seeking to improve the dependability of the energy market. We go on to specify a viable architecture for a PoA-based microgrid and provide experimental results to demonstrate that PoA is superior to proof of work (PoW) in this context.
【Abstract】The CP-ABE access control method based on blockchain realizes fine-grained access control of data and ensures the storage of ciphertext security. However, there are some problems in updating the access control policy. For example, the blockchain cannot be used as ample data storage. The ciphertext size increases with the number of attributes and the complexity of the access control policy, and the CP-ABE based on bilinear mapping is expensive to calculate. Therefore, this paper proposes dividing the ciphertext into data-related ciphertext and policy-related ciphertext, which are stored in blockchain and IPFS. It is worth noting that this paper uses the RSA-based CP-ABE encryption method, which can effectively reduce the computational cost of encryption and decryption and achieve a constant ciphertext size. In addition, we also systematically analyze and compare the advantages and costs generated by CP-ABE based on bilinear mapping and CP-ABE based on RSA. Through experimental analysis, security analysis, and formal analysis, compared with the existing access control policy update methods, the scheme proposed in this paper shows better performance when frequently updating the access control policy.
【Abstract】As many users join the smart grid system, energy companies need user energy data to manage and improve energy delivery. However, while enjoying the services provided by energy companies, the energy data submitted by users may lead to the risk of privacy leakage. To solve this problem, this paper proposes a privacy-preserving scheme for smart grid based on blockchain and multi-receiver encryption (PPBME). The scheme utilizes lightweight multi-receiver encryption, blockchain, and smart contract technologies to solve the problem of privacy leakage when user data are shared. Also, our PPBME construction employs off-chain storage technology to improve the scalability of the blockchain, so that reducing the storage pressure of the blockchain. This paper also proposes a compensation mechanism for the loss of user privacy. According to the security analysis and computational cost analysis, our PPBME scheme is efficient and secure in supporting smart grid applications.
【摘要】主从区块链是一种面向领域的、采用高效密码学原理进行大数据可信化通信及存储的新型信息处理技术.随着领域数据规模的指数级增长，现有主从区块链系统存在的查询效率低，溯源时间长等问题愈发严重.针对这些问题，提出一种面向主从区块链的多级索引构建方法（multi-level index construction method for the master-slave blockchain，MSMLI）. 首先，MSMLI引入权重矩阵，基于主链结构将整个主从区块链进行分片，并对各个分片进行权重赋值；其次，针对每个分片内的主区块链，提出基于跳跃一致性哈希的主链索引构建方法（master chain index construction method based on jump consistent hash，JHMI），输入节点关键值和索引槽位数量，输出主链索引；最后，引入布隆过滤器，改进基于列的选择函数，对各个主区块对应的从属区块链构建2级复合索引. 在3种约束条件和2类数据集上实验结果表明，MSMLI对比现有方法，平均能够缩减9.28%的索引构建时间，提升12.07%的查询效率，同时降低24.4%的内存开销.
