【影响因子】11.072
【主题类别】
区块链治理-市场治理-挖矿分析
【Abstract】When compared to traditional fiat currencies, cryptocurrencies represent a small, but growing, fraction of financial transactions. The rapid growth of cryptocurrencies has raised concerns regarding the environmental impact of this energy-intensive type of currency. In this study, water and carbon footprints associated with cryptocurrencies are assessed. These environmental footprints are then compared to the water and carbon footprints associated with conventional currencies, which is a novelty of this study. A spatially refined, bottomup analysis of the most energy-intensive aspects of each financial system is used in the comparison of these systems. Specifically, the energy use for printing money, bank branches, automated teller machines (ATM), and cashless transactions is evaluated at the country level and compared to the energy use of crypto mining around the world. Cryptocurrencies' electricity use of 236 x 106 megawatt hours (MWh) in 2021 surpassed that of the conventional transaction system, despite cryptocurrencies representing less than 0.5% of global cashless financial transactions. In terms of its water footprint, cryptocurrencies have an annual water consumption of 3670 x 106 cubic meters (m3). Cryptocurrencies' water footprint is more than double that of conventional currencies because crypto mining takes place in countries with higher water intensities for electricity. Crypto mining activities are also estimated to result in almost 139 x 106 tonnes carbon dioxide equivalent (CO2-eq) of global greenhouse gas emissions. While cryptocurrencies represent a small percentage of financial transactions, their environmental impact is much larger than the conventional financial transaction system. This study shows how regulatory changes, such as the 2021 crypto mining ban in China, and crypto mining location can have implications on the environmental footprint associated with cryptocurrency.
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】Cryptocurrency; Conventional currency; Water footprint; Carbon footprint; Spatial analysis
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 实证数据
【Author】 Pai, Sunil Park, Taewon Ball, Marshall Penkovsky, Bogdan Dubrovsky, Michael Abebe, Nathnael Milanizadeh, Maziyar Morichetti, Francesco Melloni, Andrea Fan, Shanhui Solgaard, Olav
【影响因子】10.644
【主题类别】
区块链技术-协同技术-量子区块链
【Abstract】As blockchain technology and cryptocurrency become increasingly mainstream, photonic computing has emerged as an efficient hardware platform that reduces ever-increasing energy costs required to verify transactions in decentralized cryptonetworks. To reduce sensitivity of these verifications to photonic hardware error, we propose and experimentally demonstrate a cryptographic scheme, LightHash, that implements robust, low-bit precision matrix multiplication in programmable silicon photonic networks. We demonstrate an error mitigation scheme to reduce error by averaging computation across circuits, and simulate energy-efficiency-error trade-offs for large circuit sizes. We conclude that our error-resistant and efficient hardware solution can potentially generate a new market for decentralized photonic blockchain.(c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 实验仿真
【DOI】 10.1364/OPTICA.476173
【影响因子】8.235
【主题类别】
区块链治理-市场治理-市场分析
【Abstract】Estimating the market risk is conditioned by the fat tail of the distribution of returns. But the tail index depends on the threshold of this distribution fat tail. We propose a methodology based on the decomposition of the series into positive outliers, Gaussian central part and negative outliers and uses the latter to estimate this cutoff point. Additionally, from this decomposition, we estimate extreme dependence correlation matrix which is used in the measurement of portfolio risk. For a sample consisting of six assets (Bitcoin, Gold, Brent, Standard&Poor-500, Nasdaq and Real Estate index), we find that our methodology presents better results, in terms of normality and volatility of the tail index, than the Kolmogorov-Smirnov distance, and its unnecessary capital consumption is lower. Also, in the measurement of the risk of a portfolio, the results of our proposal improve those of a t-Student copula and allow us to estimate the extreme dependence and the corresponding indexes avoiding the implicit restrictions of the elliptic and Archimedean copulas.
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】Tail index; Fat tail; Extreme dependence; Confidence level
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 实证数据
【Author】 Nguyen, Tri Katila, Risto Gia, Tuan Nguyen
【影响因子】7.307
【主题类别】
区块链应用-实体经济-无人机
【Abstract】Drone-based systems supporting Search and Rescue (SAR) missions help expeditiously improve the possibility of discovering the missing victims. Nonetheless, the current drone-based systems have some limitations, such as the need for humans in control of large-scale drones, drone's energy inefficiency, repercussion of quality of service (QoS) from abnormalities events, shortages of automaticity and real-time interactions, deficiency of swift decisions from artificial intelligence-based SAR, and underestimation of security issues in SAR systems. Therefore, developing a more advanced drone-based system is necessary to overcome these limitations. However, it is challenging to achieve the target due to trade-off relationships of technologies and strict requirements of time-critical SAR. This paper studies the feasibility of an Internet-of-Drones (IoD) system using blockchain and artificial intelligence at the edge to overcome limitations and improve SAR QoS. An advanced IoD system architecture from drones to a back-end system and end-users terminals has been proposed. Furthermore, advanced edge services and artificial intelligence at the edge have been presented for automatically searching for missing persons. In addition, computation offloading approaches have been provided to improve the energy efficiency of drones and reduce system latency. Last but not least, public and private blockchain, including Ethereum and Hyperledger Fabric, for providing secure and decentralized healthcare platform has been investigated and analyzed to enable real-time interaction between healthcare entities and improves healthcare services. The results show that the proposed system helps overcome the limitations and improve the SAR QoS. Besides, the proposed system satisfies the security requirements, including confidentiality, integrity, authentication, authorization, access control, privacy, trust, transparency, availability, automaticity, and tolerance. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】Internet-of-Drone (IoD); Edge computing; Blockchain; Search and Rescue (SAR); Energy efficiency; Computation offloading
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 实验仿真
【Author】 Bai, Qianlan Xu, Yuedong Liu, Nianyi Wang, Xin
CCF-A
【影响因子】7.231
【主题类别】
区块链技术-核心技术-挖矿策略
【Abstract】This paper studies a fundamental problem regarding the security of blockchain PoW consensus on how the existence of multiple misbehaving miners influences the profitability of selfish mining. Each selfish miner maintains a private chain and makes it public opportunistically for acquiring more rewards incommensurate to his Hash power. We first establish a general Markov chain model to characterize the state transition of public and private chains for Basic Selfish Mining (BSM), and derive the stationary profitable threshold of Hash power in closed form. It reduces from 25% for a single attacker to below 21.48% for two symmetric attackers theoretically, and further reduces to around 10% with eight symmetric attackers experimentally. We next explore the profitable threshold when one of the attackers performs strategic mining based on Partially Observable Markov Decision Process (POMDP) that only half of the attributes pertinent to a mining state are observable to him. An online algorithm is presented to compute the nearly optimal policy efficiently despite the large state space and high dimensional belief space. The profitable threshold is much lower for the strategic attacker. Last, we formulate a simple model of absolute mining revenue that yields an interesting observation: selfish mining is never profitable at the first difficulty adjustment period, but relies on the reimbursement of stationary selfish mining gains in future periods. The delay till being profitable of an attacker increases with the decrease of his Hash power, making blockchain miners more cautious about performing selfish mining.
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】Blockchains; Markov processes; Computational modeling; Bitcoin; Profitability; Delays; Publishing; Proof-of-work; selfish mining; profitability; Markov chain; partially observable MDP
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 理论模型
【Author】 Shekhtman, Louis M. Sela, Alon Havlin, Shlomo
【影响因子】3.630
【主题类别】
区块链治理-技术治理-交易网络分析
【Abstract】We consider the limits of privacy based on the knowledge of interactions in anonymous networks. In many anonymous networks, such as blockchain cryptocurrencies, dark web message boards, and other illicit networks, nodes are anonymous to outsiders, however the existence of a link between individuals is observable. For example, in blockchains, transactions between anonymous accounts are published openly. Here we consider what happens if one or more individuals in such a network are deanonymized by an outside investigator. These compromised individuals could then potentially leak information about others with whom they interacted, leading to a cascade of nodes' identities being revealed. We map this scenario to percolation and analyze its consequences on three real anonymous networks-(1) a blockchain transaction network, (2) interactions on the dark web, and (3) a political conspiracy network. We quantify, for different likelihoods of individuals possessing information on their neighbors, p, the fraction of accounts that can be identified in each network. We then estimate the minimum and most probable number of steps to a desired anonymous node, a measure of the effort to deanonymize that node. In all three networks, we find that it is possible to deanonymize a significant fraction of the network (> 50%) within less than 5 steps for values of p > 0.4. We show how existing measures and approaches from percolation theory can help investigators quantify the chances of deanonymizing individuals, as well as how users can maintain privacy.
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】Privacy; Percolation; Dark Web; Blockchain; Social networks
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 实证数据
【Author】 Ma, Zhuo Zhang, Jiawei
【影响因子】3.476
【主题类别】
区块链技术-协同技术-云计算
【Abstract】The emerging combination of Internet of Things (IoT) and aerospace integration aided by satellite and 6G communication techniques has stimulated the Internet of Unmanned Aerial Vehicles (UAVs), i.e., Internet of Drones (IoD). To accommodate and share the enormous real-time UAV data, cloud-based IoD is an inevitable choice to lower the heavy burden of mobile UAVs. Nevertheless, how to protect highly sensitive UAV data in such a honest-but-curious, open and distributed environment with resource-limited UAVs is a significant challenge. Although our previous work (PATLDAC) in SPNCE'21 devises a cloud-based UAV data access control scheme with policy privacy protection, limited access time and user traceability, it incurs inflexible and centralized cloud data storage and access as well as untrustworthy metadata in untrusted cloud environment for data access and user tracing. To this end, we further propose a blockchain-based privacy-aware data access control (BPADAC) scheme for distributed and secure UAV data sharing in cloud-based IoD. Based on fine-grained, traceable and privacy-preserving UAV data access characteristic of our previous work, we extend it by leveraging blockchain and Distributed Hash Table (DHT) for distributed and trustful UAV data access and storage, together with reliable and limited access mechanism to guarantee cloud UAV data sharing service provision. We also design public and undeniable user tracing mechanism to prevent user key abuse with traitor denial. Finally, we present formal security analysis and prototype the system leveraging the smart contracts of Ethereum blockchain for performance evaluation to show the feasibility of BPADAC.
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】Cloud computing; Autonomous aerial vehicles; Security; Access control; Blockchains; Memory; Data privacy; Cloud-based IoD; blockchain; CP-ABE; hidden access policy; limited access times
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 理论模型
【Author】 Tang, Wenpin Yao, David D.
【影响因子】2.894
【主题类别】
区块链技术-核心技术-扩展方案
【Abstract】We develop a continuous-time control approach to optimal trading in a Proof-of-Stake (PoS) blockchain, formulated as a consumption-investment problem that aims to strike the optimal balance between a participant's (or agent's) utility from holding/trading stakes and utility from consumption. We present solutions via dynamic programming and the Hamilton-Jacobi-Bellman (HJB) equations. When the utility functions are linear or convex, we derive close-form solutions and show that the bang-bang strategy is optimal (i.e., always buy or sell at full capacity). Furthermore, we bring out the explicit connection between the rate of return in trading/holding stakes and the participant's risk-adjusted valuation of the stakes. In particular, we show when a participant is risk-neutral or risk-seeking, corresponding to the risk-adjusted valuation being a martingale or a sub-martingale, the optimal strategy must be to either buy all the time, sell all the time, or first buy then sell, and with both buying and selling executed at full capacity. We also propose a risk-control version of the consumption-investment problem; and for a special case, the "stake-parity" problem, we show a mean-reverting strategy is optimal.
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】consumption-investment; cryptocurrency; continuous-time control; dynamic programming; HJB equations; Proof of Stake (PoS) protocol; risk control
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 理论模型
【DOI】 10.1111/mafi.12403
【影响因子】2.838
【主题类别】
区块链技术-协同技术-人工智能
区块链应用-实体经济-新闻传播
【Abstract】Disinformation and fake news are used by multiple actors to manipulate and influence the public with the purpose of gaining a series of advantages. This paper describes a promising solution to the increased spread of disinformation on the Internet. Our approach leverages blockchain technology combined with both crowd intelligence and federated artificial intelligence to develop efficient capabilities that address the disinformation phenomenon. The blockchain-based architecture of the platform creates a decentralized ecosystem that ensures transparency and trust, enabling the users to make correctly informed decisions in the face of disinformation. The key differentiating factor of the platform is the incorporation of both crowd and artificial intelligence in a system that can identify and respond to disinformation quickly and efficiently. The presented architecture can be used to build reactive and proactive platforms to effectively challenge disinformation.
你可以尝试使用大模型来生成摘要 立即生成
【Keywords】blockchain; fighting disinformation; crowd wisdom; artificial intelligence; governance protocol; cryptocurrency tokens
【发表时间】2023
【收录时间】2023-06-19
【文献类型】 实验仿真
【DOI】 10.3390/app13106088