【Author】 Syuhada, Khreshna Hakim, Arief Suprijanto, Djoko Muchtadi-Alamsyah, Intan Arbi, Lukman

【Source】RESOURCES POLICY

【影响因子】8.222

【主题类别】

区块链治理-市场治理-市场分析

【Abstract】Bitcoin is a new speculative investment with extremely volatile movement, thus possibly failing to act as a safe haven for crude oil when the price of this energy commodity plummeted following the global outbreak of COVID-19. Meanwhile, Tether is designed to behave similarly to the US dollar with stable fluctuation. In this study, we assessed their safe-haven properties in terms of risk reduction opportunities by proposing an improved version of Value-at-Risk (VaR) and Expected Shortfall (ES). Using vine copula-based AR-GJR-GARCH models, we demonstrated that Bitcoin exhibited inconsistent risk reduction capability for oil, particularly before COVID-19. When adding Tether into a portfolio containing oil and Bitcoin, the risk reduction was achieved for any portfolio allocation and was more pronounced amid the COVID-19 period. This suggests that Tether consistently served strong support for Bitcoin to protect oil investors against extreme risk and received a significant impact from the COVID-19 outbreak. However, the consistent safe-haven functionality of Tether was not as good as that of the US dollar in most cases, and this implied the vanishing of its stability. These results were robust when considering another asymmetric volatility model and another dependence model. Furthermore, the proposed improved VaR and ES forecasts outperformed their corresponding unimproved version in quantifying portfolio risk and therefore provided a more accurate assessment of safe-haven roles.

你可以尝试使用大模型来生成摘要 立即生成

【Keywords】Crude oil; Cryptocurrency; Stablecoin; Value-at-Risk; Expected Shortfall; COVID-19

【发表时间】2022

【收录时间】2023-03-02

【文献类型】 实证数据

【DOI】 10.1016/j.resourpol.2022.103111

【Author】 Li, Jiatao Han, Dezhi Wu, Zhongdai Wang, Junxiang Li, Kuan-Ching Castiglione, Arcangelo

【Source】FUTURE GENERATION COMPUTER SYSTEMS-THE INTERNATIONAL JOURNAL OF ESCIENCE

【影响因子】7.307

【主题类别】

区块链应用-实体经济-供应链

【Abstract】With the increasing sales of the medical device market, the medical incidents caused by passive medical devices are increasing, which needs to be solved from the medical device supply chain. In addition, there are complex rights retrieval and assignment problems in the medical device supply chain system, and the traditional Role-based Access Control (RBAC) model is no longer suitable for the actual application environment of the supply chain.This article combines the traditional RBAC model and the Attribute-based Access Control (ABAC) model for access control management in the medical device supply chain to overcome the limitations abovementioned, taking advantage of the ABAC model's flexibility to achieve granular and dynamic management of permissions, as also the RBAC model to simplify the permissions management of the entire system. Blockchain technology's traceability, non-tampering, and decentralization features are essential to eliminate passive and inferior medical equipment sales activities, solving the problem of mutual mistrust and 'Information Silo' between the two sides of medical device transactions. The access control model is implemented in the blockchain's smart contract, providing granular and dynamic authority management for the medical equipment supply chain and guaranteeing the security and privacy of medical device information in the supply chain. Three smart contracts on Hyperledger Fabric are designed for device management information, storage of implemented access control models, and implementation of access control policies. Experimental results show that the entire system is stable, ensuring high throughput and high security and promising.(c) 2022 Elsevier B.V. All rights reserved.

你可以尝试使用大模型来生成摘要 立即生成

【Keywords】Hyperledger fabric; ABAC model; RBAC model; Smart contract; Supply chain; Medical field

【发表时间】2023

【收录时间】2023-03-02

【文献类型】 理论模型

【DOI】 10.1016/j.future.2022.12.037

【Author】 Ilyas, Benkhaddra Kumar, Abhishek Setitra, Mohamed Ali Bensalem, ZineEl Abidine Lei, Hang

【Source】TRANSACTIONS ON EMERGING TELECOMMUNICATIONS TECHNOLOGIES

【影响因子】3.310

【主题类别】

区块链治理-技术治理-拒绝服务攻击检测

【Abstract】The attack named Distributed Denial of Service (DDoS) that takes place in the large blockchain network requires an efficient and robust attack detection and prevention mechanism for authenticated access. Blockchain is a distributed network in which the attacker tries to hack the network by utilizing all the resources with the application of enormous requests. Several methods like Rival Technique, filter modular approach and so on, were developed to detect and prevent the DDoS attack in the blockchain; still, detection accuracy is a challenging task. Hence, this research introduces an efficient technique using optimization-based deep learning by considering the blockchain network and smart contract for the detection and prevention of DDoS attacks. Based on the user request, the traffic is analyzed, and the verification using the smart contract is made to find the authenticated user. After the verification, the response is provided for the authenticated user, and the suspicious traffic is utilized for the detection of DDoS attacks using the Poaching Raptor Optimization-based deep neural network (Poaching Raptor-based DNN), in which the classifier is tuned using the proposed optimization algorithm to reduce the training loss. The proposed algorithm is designed by hybridizing the habitual practice of the raptor by considering the concurring behavior, hunting style along with poaching behavior of the Lobo to enhance the detection accuracy. After the attack detection, the nonattacker is responded, and the attacker is prevented by entering the IP/MAC address in the logfile. The performance of the proposed method is evaluated in terms of recall, precision, FPR, and accuracy and obtained the values of 96.3%, 98.22%, 3.33%, and 95.12%, respectively.

你可以尝试使用大模型来生成摘要 立即生成

【Keywords】

【发表时间】

【收录时间】2023-03-02

【文献类型】 实证数据

【DOI】 10.1002/ett.4729

【Author】 Rech, Frederik Yan, Chen Bagonza, Amon Pinter, Lubomir Musa, Hussam

【Source】PRAGUE ECONOMIC PAPERS

【影响因子】0.797

【主题类别】

区块链治理-市场治理-数字货币

【Abstract】The research and investment community seems to ignore the long-term sustainability of Bitcoin, which is reflected in four flaws: transaction fees, miners' revenue, concentration and electricity consumption. While most of the authors have aimed to examine one topic at a time, with a particular interest in electricity consumption and carbon footprint, the aim of this paper is to examine all these issues simultaneously to provide a more comprehensive view on long-term sustainability of Bitcoin. This paper looks at these flaws and reveals why Bitcoin is not sustainable in the long run, how decentralization is being lost, how the design is putting artificial and unrealistic pressure on the ecosystem, while all being powered by an unjustifiable amount of dirty electricity sources. Our main findings are as follows. Firstly, transaction fees are already high and set to increase in time, further discriminating small transactions against big ones. Secondly, miners' revenue comes mostly from the block reward. The block reward is the main income source for miners, but is set to be cut on a regular basis, making miners' revenue not sustainable in the long run. Thirdly, miner concentration is already an issue, with a possibility of deepening even more and diminishing the idea of decentralization. Fourthly, the high electricity demand and the associated carbon footprint thus cannot be justified by any means. We deem our results useful for overall policy and regulatory implications.

你可以尝试使用大模型来生成摘要 立即生成

【Keywords】Bitcoin; transaction fees; miners? revenue; miner concentration; Electricity consumption

【发表时间】2022

【收录时间】2023-03-02

【文献类型】 观点阐述

【DOI】 10.18267/j.pep.817

【Author】 Ismail, Firdous Sadaf Mohd Adane, Dattatraya S.

【Source】INTERNATIONAL JOURNAL OF NEXT-GENERATION COMPUTING

【影响因子】0.000

【主题类别】

区块链应用-实体经济-应用集

【Abstract】Advantages of decentralized systems over centralized approaches are reason for increasing incorporation of blockchain technology in almost every digital task. Core benefits of blockchain include decentralization, persistency, auditability and anonymity. This paper discusses Blockchain Technology from the perspective of related attributes, applications and challenges. Specifically, we try to elaborate on the current work pertaining to application of Blockchain Technology to different domains such as Internet of Things (IoT), Artificial Intelligence (AI), Big Data and Software Defined Networking (SDN) keeping in view the challenges of optimized storage, scalability and security.

你可以尝试使用大模型来生成摘要 立即生成

【Keywords】Blockchain Technology; Smart Contract; Artificial Intelligence; Internet of Things

【发表时间】2022

【收录时间】2023-03-02

【文献类型】 观点阐述

【DOI】

【Author】 Morais, Rui Crocker, Paul Leithardt, Valderi

【Source】ALGORITHMS

【影响因子】0.000

【主题类别】

区块链技术-核心技术-共识机制

【Abstract】This paper presents the research undertaken with the goal of designing a consensus algorithm for cryptocurrencies with less latency than the current state-of-the-art while maintaining a level of throughput and scalability sufficient for real-world payments. The result is Nero, a new deterministic leaderless byzantine consensus algorithm in the partially synchronous model that is especially suited for Directed Acyclic Graph (DAG)-based cryptocurrencies. In fact, Nero has a communication complexity of O(n(3)) and terminates in two message delays in the good case (when there is synchrony). The algorithm is shown to be correct, and we also show that it can provide eventual order. Finally, some performance results are given based on a proof of concept implementation in the Rust language.

你可以尝试使用大模型来生成摘要 立即生成

【Keywords】consensus; byzantine; directed acyclic graph

【发表时间】2023

【收录时间】2023-03-02

【文献类型】 实验仿真

【DOI】 10.3390/a16010038