【Abstract】The application of blockchain technology in supply chain management has become a popular area of discussion in research and practice. This paper develops a computational, data-driven synthesis of the scholarly literature versus news media on BT-enabled supply chain management (BT-SCM) to uncover major trends, understand how academic research is aligned with business practice, and find out existing gaps. Through text mining and topic modeling of 1148 full-text research papers and 5130 news articles, major themes within each domain, their patterns of evolution over time, and the depth and breadth of their associations were identified. Mapping ana-lyses were also conducted based on the supply chain operations reference (SCOR) model and the main SCM research streams to further explore existing knowledge gaps. The findings revealed that BT-enabled supply chain asset management, BT-enabled reverse logistics and closed-loop supply chain, and actual versus anticipated performance outcomes of BT-SCM are among important pathways for future research. The findings also high-lighted where there is more need to enhance the practical relevance of BT-SCM research considering advances in business adoption. The paper provides a comprehensive, unbiased assessment of the BT-SCM knowledge land-scape and a taxonomy of the research questions related to the technical and managerial aspects of BT-SCM that are particularly useful for the community of researchers in the field. It offers a practical framework that can be applied to assess the academic literature on other emerging technologies in SCM where state-of-the-practice is key to guiding research efforts.
【Abstract】Maintenance of generation units is a measure to ensure the reliability of power systems. In this paper, a novel blockchain-based truthful condition-based maintenance of generation units (T-CBMGU) platform is proposed to innovate and upgrade state-of-the-art CBMGU. In addition, two valid inequalities are proposed to accelerate the convergence speed of Benders decomposition in maintenance scheduling process. The proposed valid inequalities are formulated based on technical/physical analysis and greedy-based heuristic initialization. More specifically, for data acquisition and failure rate diagnosis/prognosis processes, T-CBMGU can ensure the immutability of the collected operational data. In this way, the influence of tampered data on the diagnosis/prognosis results in state-of-the-art CBMGU can be reduced. For maintenance scheduling and bidding to change scheduled time slot processes, in state-of-the-art CBMGU, the decision makers, i.e., independent system operators (ISOs), may not be trusted. However, in T-CBMGU, the scheduling and bidding processes are implemented automatically via smart contracts rather than by the ISOs; as such, incentives to manipulate data can be avoided. Finally, regarding performance of maintenance actions, in contrast to state-of-theart CBMGU, the implementation process can be truthfully recorded by the T-CBMGU platform, which facilitates backtracking of responsibility. Then, the T-CBMGU platform and the valid inequalities are tested for the IEEE 300-bus power system. Furthermore, cases with tampered data and distrust caused by fairness manipulation are simulated to show the importance of using T-CBMGU. Finally, the Benders decomposition algorithm with valid inequalities is compared with other solvers to demonstrate its fast convergence speed. (C) 2022 The Author(s). Published by Elsevier Ltd.
【Abstract】This study analyses the impact of different uncertainties on commodity markets to assess commodity markets' hedging or safe-haven properties. Using time-varying dynamic conditional correlation and wavelet-based Quantile-on-Quantile regression models, our findings show that, both before and during the COVID-19 crisis, soybeans and clean energy stocks offer strong safe-haven opportunities against cryptocurrency price uncertainty and geopolitical risks (GPR). Soybean markets weakly hedge cryptocurrency policy uncertainty, US economic policy uncertainty, and crude oil volatility. In addition, GSCI commodity and crude oil also offer a weak safe-haven property against cryptocurrency uncertainties and GPR. Consistent with earlier studies, our findings indicate that safe-haven traits can alter across frequencies and quantiles. Our findings have significant implications for investors and regulators in hedging and making proper decisions, respectively, under diverse uncertain circumstances.
【Abstract】The connection between the cryptocurrency and precious metal markets has attracted a lot of interest among academics, investors, and policymakers. The focus of this paper is to examine the role of bullish, neutral, and bearish investors' sentiments on the connection between the five (5) most traded crypto-currencies and the precious metals market. The following findings are perceptible from our analyses. First, in the spillover tests, there exists a significant high level of connection between the two markets. Second, the spillover results also reveal that tetherum and silver are net receivers of the shocks, while most of the cryptocurrencies are net transmitters of the volatility. Third, the BDS test shows strong evidence of non -linearity is a very crucial factor to be put into consideration when examining the role of investors' senti-ments on the interactions between the cryptocurrency and precious metals markets. Fourth, the non -parametric causality-in-quantile test confirms that the connectedness between the cryptocurrency and precious metal markets is speculation driven. These results have important policy implications for pol-icymakers and market participants.(c) 2022 Board of Trustees of the University of Illinois. Published by Elsevier Inc. All rights reserved.
【Abstract】Technological advancements have always been influencing our lives. Recently, the Internet of Things (IoT) and Blockchain (BC) are emerging as potentially disruptive technologies. Whereby, the IoT is a system of inter-related devices with unique identifiers for data sharing and device management and control. IoT is based on the inte-gration of traditional technologies including embedded systems, wireless sensor networks, control systems, and automation. While, the concept of IoT is continuously evolving with the convergence of multiple technologies including real-time analytics, machine learning, commodity sensor, and embedded systems. On the other hand, BC technology is a distributed ledger used to maintain the transaction logs of a network, and it has started revolutionizing data provenance, storage, secure, and traceable transaction management systems. There is limited use of blockchain technology for a fully decentralized, untrusted, and secure environment in the field of IoT. This article reviews the current state-of-art blockchain technology and its current utilization in different application domains of IoT. Furthermore, it presents the use of blockchain technology with digital ledger technology (DLT) and IoT. Similarly, the notable challenges of BC and IoT integration are presented. To the best of our knowledge, there is no such SLR available that provides a comprehensive review in this domain. Applying blockchain to solve IoT problems improves IoT security. Moreover, a taxonomy of application domains is pre-sented, which can be integrated with BC and IoT. The article identifies and discusses open research issues and challenges that need to be addressed to harness the potential of BC technology for IoT.
【Abstract】The practical Byzantine fault tolerant (PBFT) consensus mechanism is one of the most basic consensus algorithms (or protocols) in blockchain technologies. Thus its performance evaluation is an interesting and challenging topic due to the higher complexity of its consensus work in a peer-to-peer network. This study describes a simple stochastic performance model of the PBFT consensus mechanism. This model is refined not only as a queuing system with complicated service times but also as a level-independent quasi-birth-and-death (QBD) process. With regard to the level-independent QBD process, we apply the matrix-geometric solution to obtain the necessary and sufficient condition under which the PBFT consensus system is stable and then numerically compute the stationary probability vector of the QBD process. Thus, we provide four useful performance measures for the PBFT consensus mechanism, and we can numerically calculate these performance measures. Finally, we use numerical examples to verify the validity of our theoretical results and demonstrate how the four performance measures are influenced by certain key parameters of the PBFT consensus. Considering theory of multi-dimensional Markov processes, we are optimistic that the methodology and results presented in this study are applicable to a wide range of PBFT consensus mechanism and even other types of consensus mechanisms.
【Abstract】We use wavelet coherence analysis on global COVID-19 fear index and, soft commodities' spot and futures prices to investigate safe-haven properties of soft commodities over the period from January 28, 2020 to April 29, 2021. Our findings show that each of the sampled soft commodities shows safe-haven behavior in one of the spot or futures markets and for one of the short-term or long-term investors during the times of COVID-19. Our results also show that safe-haven properties of soft commodities are contingent upon the nature of the commodity. The findings of our mean-variance portfolio analysis indicate that the portfolios with commodity futures are less risky and efficient compared to the portfolio containing stocks only, thus robustly supporting the safe-haven properties of soft commodities during COVID-19. Our results not only have important implications for individual investors and asset managers in suggesting particular soft commodities to strengthen safe-haven and diversification features of their portfolios but also can assist the policy makers to understand and disentangle health fear dimension of several interlocking dynamics affecting the spot and futures prices of soft commodities during COVID-19.
【Abstract】Blockchain protocols require nodes to verify all received transactions before forwarding them. However, massive spam transactions cause the participants in blockchain systems to consume many resources in verifying and propagating transactions. This paper proposes a reputation-based mechanism to increase the efficiency of processing transactions by considering the reputations of the sending nodes. Reputations are in turn adjusted based on the quality of transaction processing. Our proposed reputation-based mechanism offers three main contributions. First, we modify the verification strategy so that nodes set a probability of verifying a received transaction considering the likelihood of it being spam: transactions from a node with a low reputation have a high probability of being verified. Second, we optimize the transaction forwarding protocol to reduce propagation delay by prioritizing forwarding transactions to reputable receivers. Third, we design a data request protocol that provides alternative data exchange methods for nodes with different reputations. A series of simulations demonstrate the performance of our reputation-based mechanism.
【Abstract】In the present era, the consensus for blockchain is of three types: consortium/permissioned, decentralized/permissionless, and somewhat decentralized. Presently, security and privacy of blockchain scenarios are in four directions: auditability and transparency, accountability and non-repudiation, contract privacy, and transactional privacies. Blockchain works on multilayered architectures with its consensus mechanisms. In this paper, important mechanisms of various consensus protocols for application specific usage are analyzed. In general, these consensus mechanisms have four groups of properties; all are examined and discussed. Moreover, the security analysis is shown. Furthermore, the paper examines the elliptic curve digital signature algorithm (ECDSA), which is in use by the cryptocurrencies along with many blockchain-based systems. Moreover, a variant of ECDSA (vECDSA) is also considered. In particular, ECDSA and vECDSA are compared in this research. In addition, modeling and analysis aspects related to the security and concurrency aspects of CPS are discussed. In particular, Petri-net-based models of CPS are considered, especially in terms of liveness and boundedness properties of the system.
【Keywords】cyber-physical systems (CPS); consensus protocols; security; Petri nets; Proof of Work (PoW); elliptic curve cryptography (ECC); ECDSA; elliptic curve discrete logarithm problem (ECDLP); vECDSA; Proof of Stake (PoS)
【Abstract】The consensus mechanism is a core component of Blockchain technology, allowing thousands of nodes to agree on a single and consistent view of the Blockchain. A carefully selected consensus mechanism can provide attributes such as fault tolerance and immutability to an application. The Internet of Things (IoT) is a use case that can take advantage of these unique Blockchain properties. IoT devices are commonly implemented in sensitive domains such as health, smart cities, and supply chains. Resilience and data integrity are important for these domains, as failures and malicious data tampering could be detrimental to the systems that rely on these IoT devices. Additionally, Blockchains are well suited for decentralised networks and networks with high churn rates. A difficulty involved with applying Blockchain technology to the IoT is the lack of computational resources. This means that traditional consensus mechanisms like Proof of Work (PoW) are unsuitable. In this paper, we will compare several popular consensus mechanisms using a set of criteria, with the aim of understanding which consensus mechanisms are suitable for deployment in the IoT, and what trade-offs are required. We show that there are opportunities for both PoW and PoS to be implemented in the IoT, with purpose-made IoT consensus mechanisms like PoSCS and Microchain. Our analysis shows that Microchain and PoSCS have characteristics that are well suited for IoT consensus.
【Abstract】The COVID-19 pandemic further outlined the importance of global healthcare services provisioning for diagnosing and treating patients who tend to travel and live for large periods away from home and can be anywhere at any given time. Advances in technology enable healthcare practitioners to access critical data regarding a person's health status to provide better services. Medical data are sensitive in nature, and therefore, a reliable mechanism should ensure that only authorized entities can access data when needed. This paper, through a layered consideration of a Globalized Healthcare Provisioning Ecosystem (GHPE), reveals the interdependencies among its major components and suggests a necessary abstraction to identify requirements for the design of an access control suitable for the ecosystem. These requirements are imposed by the nature of the medical data as well as by the newly introduced potentials of Internet of Medical Things (IoMT) devices. As a result, an attribute-based access control framework is proposed aiming to provide prompt and secure access to medical data globally by utilizing state-of-the-art technologies and standards, including Next-Generation Access Control (NGAC), blockchain and smart contracts. Three types of smart contracts are proposed that enable access control to implement attribute and policy stores where policy classes and attributes are decentralized and immutable. In addition, the usage of blockchain-based distributed identities allows patients to be in control of access to their medical data and also enables healthcare service providers to access medical data promptly and reliably through the proposed access control framework. The qualitative characteristics of the proposed approach toward a decentralized and patient-centric access control in GHPE are demonstrated and discussed based on an application paradigm.
【Abstract】Recommender system for the IoT (RSIoT) has attracted considerable attention. By leveraging emerging technologies such as the Internet of Things (IoT), artificial intelligence, and blockchain, RSIoT improves various indicators of residents' life. However, data integrity threats may affect the accuracy and consistency of the data particularly in the IoT environment where most devices are inherently dynamic and have limited resources that could fail in ensuring the quality of data transmission. Prior work has focused on processing big data and ensuring their integrity by considering cloud storage service as the popular way. In this article, we address integrity of data leveraging blockchain capabilities to ensure the integrity of the critical data. We adapted the Ethereum blockchain to our RCS for ensuring integrity of data during sharing them between doctor and patient without handling their data by third party. We build four smart contracts that enable our system of gaining more advantage of blockchain. We evaluated the performance of our smart contracts in Kovan and Rinkeby test networks. The preliminary results show the feasibility and effectiveness of the proposed solution.
【Abstract】Since the last decade, cloud-based Electronic Health Records (EHRs) have achieved important consideration to facilitate remote access of patient medical records. The modern evolution of Healthcare 4.0 applying the Internet of Things (IoT) elements with cloud computing reforms to obtain remote medical services has grown the researcher's recognition with the perspective of the smart city. The Healthcare 4.0 standard has consists of different layers to perform medical operations like periodic data sensing, data storage, data sharing, and auditing. The delicate and private medical records of victims lead to numerous difficulties while defending them from hackers. Therefore saving, obtaining, and distributing the patient medical data on the remote storage requires safety attentions so that medical records should not be compromised by the authorized user's components of E-healthcare systems. To achieve secure medical data storage, sharing, and accessing in Cloud Service Provider (CSP), various cryptography algorithms have been designed so far. But these traditional resolutions disappointed to manage the trade-off among the provisions of EHR safety in terms of computational competence, user-side verification, service-side verification, security, and without the trusted third party. Blockchain-based security techniques achieved notable recognition due to the strength to give strong security provisions for medical records storage and sharing with the least computation forces. The blockchain made focused on bitcoin technology among the researchers. Employing the blockchain in healthcare systems has been of current interest. This paper aims to present a systematic study of different blockchain-based solutions for the smart healthcare 4.0 system. The recent blockchain-based security solutions have been reviewed first and, then we presented a research gap considering the various parameters. The outcome of this paper discusses the current research gaps, the challenges of implementing the blockchain-based secure healthcare system, and the future roadmap or solutions.
【Abstract】Location-based services currently face two critical issues: an insufficient number of anonymous users and the problem of location semantic homogeneity. To prevent location homogeneity attacks, we suggest a blockchain-based anonymization approach. This scheme introduces blockchain to store the anonymous process of the requesting user and collaborating user as evidence, establishes an incentive mechanism to promote cooperation between the two parties, and then selects users who meet the semantic threshold through the location semantic tree to construct the final anonymous set. The security analysis and simulation experiments demonstrate that the scheme suggested in this article can effectively motivate and constrain each user. The semantic security value is close to the maximum value of 1, preventing homogeneity attacks caused by location semantics and protecting users' location privacy.
【Abstract】Quantum money allows banks to cast quantum money states that can be verified later and cannot be forged. Usually, the transmission of quantum states between banks and user needs to be involved. It is difficult to ensure the safe transmission of quantum states, which will lead to the loss and reconstruction of quantum money. In this paper, we make and store quantum states by the bank, and then the bank adds its own signature, which is public and verifiable by anyone. After the user adds his signature, the quantum currency is considered to be effective. We propose a trading application based on quantum money. We combine quantum money with blockchain to increase the security of quantum money. In addition, the analysis results show that our protocol is secure against some attacks.
【Abstract】A growing literature has employed the existing generalized spillover measures to measure the connectedness - or market integration - of cryptocurrencies. This method, while useful, does not properly control for the cross-correlations of the cryptocurrencies when computing aggregate spillovers from all others to any given cryptocurrency, whereas the joint spillover method of Lastrapes and Wiesen (2021) does. This paper further describes the novel multivariate conditioning sets employed by the joint spillover method. By employing these two techniques and evaluating the differences in the results, we demonstrate that controlling for the cross-correlations of cryptocurrencies matters for measuring aggregate spillovers and the overall connectedness of the cryptocurrency market. Using data on ten of the most traded cryptocurrencies, we find that the generalized spillover index overestimates overall connectedness by over nine percentage points relative to the new joint spillover index. This difference varies temporally and across cryptocurrencies.
【Abstract】The internet of things (IoT) is now advancing at a tremendous pace. Devices in the IoT can connect and communicate in a fully autonomous mode. Because of its autonomy and numerous infractions of security policies, the IoT network is subject to various security risks. However, because of this autonomy, dependable security and storage mechanisms for authentication to share data across IoT devices are essential. Furthermore, since it has initially been popularized in Bitcoin, blockchain development has accelerated. Blockchain can be used to solve security challenges in the IoT. Making secure communication between IoT devices is one approach to accomplish this. To address this issue, we present an effective technique for intranetwork and internetwork device-to-device secure communication that enables IoT device identification and authentication while also providing secure communication in an open environment. The method also provides data integrity in addition to authentication and secure communication. We have presented informal security analysis, which confirms that there is no important security threats in our protocol. The performance of the protocol is also better in comparison with previously published papers.
【Abstract】Rapid development of blockchain technologies promote involvement of methods using categorize research topics, identify the most topical trends, and ascertain the main publishing sources related to electronic data interchange. The study is based on an analysis of scientific publications (2015-2019 years) and investigation on the theory of supply chain and logistic the research is based on theoretical research methods that include a literature review and content analysis. The authors have reviewed 9,780 primary papers published between the years 2015-2019 from major academic databases (EBSCO, Elsevier ScienceDirect, Emerald Insight, Scopus, SSRN; Springer SpringerLink, Web of Science). The results of the research are presented, which at the logistics position describing the usage of blockchain technology for electronic data interchange in multiple industries. In concluding the research, the authors present the research gaps discovered, major trends, most discussed industries and suggestions for future research.
