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IEEE Annual Conference on Decision and Control

作者： Guodong Shi Alexandre Proutiere Mikael Johansson Karl H. Johansson ACCESS Linnaeus Centre School of Electrical Engineering Royal Institute of Technology Stockholm 10044 Sweden

ISBN: (纸本)9781467357159

We study convergence properties of a randomized consensus algorithm over a graph with both attractive and repulsive links. At each time instant, a node is randomly selected to interact with a random neighbor. Depending on if the link between the two nodes belongs to a given subgraph of attractive or repulsive links, the node update follows a standard attractive weighted average or a repulsive weighted average, respectively. The repulsive update has the opposite sign of the standard consensus update. In this way, it counteracts the consensus formation and can be seen as a model of link faults or malicious attacks in a communication network, or the impact of trust and antagonism in a social network. Various probabilistic convergence and divergence conditions are established. A threshold condition for the strength of the repulsive action is given for convergence in expectation: when the repulsive weight crosses this threshold value, the algorithm transits from convergence to divergence. An explicit value of the threshold is derived for classes of attractive and repulsive graphs. The results show that a single repulsive link can sometimes drastically change the behavior of the consensus algorithm. They also explicitly show how the robustness of the consensus algorithm depends on the size and other properties of the graphs.

关键词： random networks consensus algorithms gossiping sensor networks opinion dynamics social networks Random Network Social Networks threshold condition Converge Social Capital Sensor networks Gossip networks(communications) Weighted Average

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Formal Verification of an Industrial Distributed Algorithm: An Experience Report 9th

Formal Verification of an Industrial Distributed Algorithm: ...

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9th International Symposium on Leveraging Applications of Formal Methods, Verification and Validation

作者： Kosmatov, Nikolai Longuet, Delphine Soulat, Romain Thales Res & Technol Palaiseau France

ISBN: (纸本)9783030613617;9783030613624

Verification of distributed software is a challenging task. This paper reports on modeling and verification of a consensus algorithm developed by Thales. The algorithm has an arbitrary number of processes (nodes), which can possibly fail and restart at any time. Communications between nodes are periodic, but completely asynchronous. The goal of this algorithm is that, after a given amount of time since the last status change, the network of nodes agrees on a list of working nodes. Our verification approach is based on modeling both the source code of the algorithm and the possible interleavings of executions. We present how we were able to scale up to 100 processes using the rely-guarantee based technique. Some of the initially expected properties did not hold, and generated counter-examples helped to fix and prove them. We also successfully verified other consensus algorithms at Thales with the same approach. We describe our experiments on applying several model-checking tools and a symbolic execution tool, and present some lessons learned.

关键词： Distributed algorithm verification consensus algorithms Symbolic model checking Rely-guarantee Symbolic execution

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Analysis of Secured Hash Algorithm-256 in a Blockchain-Based Money Transaction System

Analysis of Secured Hash Algorithm-256 in a Blockchain-Based...

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2023 International Conference on Innovative Computing, Intelligent Communication and Smart Electrical Systems, ICSES 2023

作者： Singh, Jobanbir Sharma, Anubhav Kaur, Sandeep Chandigarh University Department of Computer Science Engineering Punjab India

ISBN: (纸本)9798350319200

Blockchain is not an antique term in the history of computer programming. Introduced and developed only in the last decade, Blockchain has become the first choice of all cyber security engineers. The study is concentrated on the integration of blockchain technology with a few of the strongest hashing algorithms with a focus on SHA-256. The study aims to create and compare adequate and feasible methods to enhance the accuracy and confidence among various enterprises whose systems accompany blockchainbased transactions. The study acknowledges that there has been an increase in the use of Bitcoin in the international market. With the increase in investment in cryptocurrency, blockchain has become one of the most future-proof and sensitive technologies available in the market. The following context discusses the origin of blockchain, the platforms and scripts standardized, and the algorithms that are involved or have the potential to make blockchain cryptographically stronger. It demonstrates the need for a new paradigm to improve efficiency and accuracy. © 2023 IEEE.

关键词： blockchain technology consensus algorithms cryptography hash functions software performance

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A Scalable Strategy for consensus-Based Secondary Reliable Control of DC Microgrids by Graph Decomposition

A Scalable Strategy for Consensus-Based Secondary Reliable C...

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第35届中国过程控制会议

作者： Yangjie Chen Minrui Fei Shanghai Key Laboratory of Power Station Automation Technology School of Mechatronic Engineering and Automation Shanghai University

This article examines a consensus-based method for reliable distributed secondary control in DC microgrids（mGs）,focusing on achieving effective current sharing and voltage balancing. To accomplish this objective, it is assumed that each Distributed Generation Unit（DGU） is equipped with a decentralized primary controller to maintain voltage stability. However,the core issue is that the problem exhibits non-convexity and demonstrates poor scalability as the size of DC mGs ***, Our objective is to develop a scalable strategy for distributed H control design. considering limited model information exchange and arbitrary control structures. To achieve this, we adopt a graph-theoretical perspective for the structured optimal H design of DC mGs, incorporating linear matrix inequality（LMI） constraints. By utilizing chordal graph decomposition,we decompose the design problem into low-dimensional problems with coupled constraints. Finally, we introduce a scalable strategy based on the alternating direction method of multipliers（ADMM） to solve the H optimization problem. This strategy ensures the stability of the closed-loop DC m Gs system by tolerating certain faults in DC mGs components through limited model information exchange.

关键词： DC microgrids consensus algorithms Graph Decomposition ADMM

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Event-based consensus for a class of heterogeneous multi-agent systems: An LMI approach

Event-based consensus for a class of heterogeneous multi-age...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Amir Amini Arash Mohammadi Amir Asif Electrical and Computer Engineering Concordia University Montreal QC Canada

ISBN: (纸本)9781509041183

Based on the theory of linear matrix inequalities (LMI), this paper proposes an event-based distributed consensus algorithm for linear multi-agent/sensor networks that are heterogeneous. The proposed scheme is event-based in the sense that each agent transmits its information to its neighbouring nodes only under predefined circumstances. Ensuring the stability of the closed-loop system, the Lyapunov theorem is utilized to compute design parameters (heterogeneous controller gains and transmission threshold) used in the proposed consensus algorithm. Numerical simulations demonstrate a performance gain in the convergence time and a reduction in the number of data transmissions with the proposed approach.

关键词： consensus algorithms Event-based transmission Distributed agent/sensor networks Linear Matrix Inequalities (LMIs) Event-based Interim Local Management Interface data transmission Multi-agent systems

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Newton-Raphson consensus for distributed convex optimization

Newton-Raphson consensus for distributed convex optimization

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IEEE Conference on Decision and Control

作者： Filippo Zanella Damiano Varagnolo Angelo Cenedese Gianluigi Pillonetto Luca Schenato Univ. of Padova Italy

ISBN: (纸本)9781612848006

We study the problem of unconstrained distributed optimization in the context of multi-agents systems subject to limited communication connectivity. In particular we focus on the minimization of a sum of convex cost functions, where each component of the global function is available only to a specific agent and can thus be seen as a private local cost. The agents need to cooperate to compute the minimizer of the sum of all costs. We propose a consensus-like strategy to estimate a Newton-Raphson descending update for the local estimates of the global minimizer at each agent. In particular, the algorithm is based on the separation of time-scales principle and it is proved to converge to the global minimizer if a specific parameter that tunes the rate of convergence is chosen sufficiently small. We also provide numerical simulations and compare them with alternative distributed optimization strategies like the Alternating Direction Method of Multipliers and the Distributed Subgradient Method.

关键词： distributed optimization convex optimization consensus algorithms multi-agent systems Newton-Raphson methods

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Scaling Private Collaborated Consortium Blockchains Using State Machine Replication Over Random Graphs

Scaling Private Collaborated Consortium Blockchains Using St...

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作者： Parth Shukla University of Windsor

学位级别：硕士

Blockchain technology has redefined the way the software industry's core mechanisms operate. With recent generations of improvement observed in blockchain, the industry is surging ahead towards replacing the existing computing paradigms with consortium blockchain-enabled solutions. For this, there is much research observed which aims to make blockchain technology's performance at par with existing systems. Most of the research involves the optimization of the consensus algorithms that govern the system. One of the major aspects of upcoming iterations in blockchain technology is making individual consortium blockchains collaborate with other consortium blockchains to validate operations on a common set of data shared among the systems. The traditional approach involves requiring all the organizations to run the consensus and validate the change. This approach is computationally expensive and reduces the modularity of the system. Also, the optimized consensus algorithms have their specific requirements and assumptions which if extended to all the organizations leads to a cluttered system with high magnitudes of dependencies. This thesis proposes an architecture that leverages the use of state machine replication extended to all the nodes of different organizations with seamless updates over a random graph network without involving all the nodes participating in the consensus. This also enables organizations to run their respective consensus algorithms depending on their requirements. This approach guarantees the finality of consistent data updates with reduced computations with high magnitudes of scalability and flexibility.

关键词： Blockchains Byzantine Fault Tolerance consensus algorithms Cryptograpgy Decentralized Computing Distributed Ledger

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Security of Cryptocurrencies in blockchain technology: State-of-art, challenges and future prospects

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JOURNAL OF NETWORK AND COMPUTER APPLICATIONS 2020年 163卷 102635-102635页

作者： Ghosh, Arunima Gupta, Shashank Dua, Amit Kumar, Neeraj Birla Inst Technol & Sci Dept Comp Sci & Informat Syst Pilani Rajasthan India Thapar Inst Technol & Sci Comp Sci & Engn Dept Patiala Punjab India Asia Univ Dept Comp Sci & Informat Engn Taichung Taiwan King Abdulaziz Univ Jeddah Saudi Arabia

In contemporary era of technologies, blockchain has acquired tremendous attention from various domains. It has wide spectrum of applications ranging from finance to social services and has greatly influenced the emerging business world. Since, blockchain technology is getting embedded in the e-commerce services, the crypto-currencies are gaining huge prevalence. Bitcoin and ethereum are few such crypto currencies, which have utilized decentralized nature of blockchain. Blockchain can be considered as a distributed database system containing immutable ledgers, which are prone to attack by malicious users. Although, from the initial digital currency to the present smart contract, the utilities of blockchain have been harnessed, the innovative technology has to rely on cryptography for its security. There are several reports, which emphases on the vulnerabilities and security of blockchain, however, there is a lack of a comprehensive and methodical survey in both application and technical views. In this survey article, the authors cover various aspects related to blockchain including its taxonomies and the situations in which a particular category of blockchain should be applied. The authors also focusses on the structure of blockchain and the working of the ongoing transactions in the cryptocurrency network. In addition, the authors also specify various categories of consensus protocols, smart contracts, forks, techniques for generating the consensus. A detailed taxonomy of blockchain along with their features and related real-world applications is also discussed. In addition, existing key platforms of blockchain related to the cryptocurrencies, hyperledger and multichain are also discussed. Existing emerging vulnerabilities of blockchain related to the recent attacks on bitcoin and etherum is also presented along with the defensive methodologies and future trends in blockchain.

关键词： Blockchain Distributed ledger Decentralization Cryptocurrency Digital currency consensus algorithms Smart contract Security

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Power sharing in actuated DC grids in mesh topology

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SUSTAINABLE ENERGY GRIDS & NETWORKS 2021年 28卷

作者： Contzen, Miguel Parada Biobio Univ Elect & Elect Dept Concepcion Chile

This paper deals with the problem of power sharing in DC micro-grids in mesh topology with multiple active buses. We formally analyze the feedback loop composed by the micro-grid as a multi-agents process, the DC generation units as actuators, the distributed arbitrary loads as disturbances, and a linear consensus based control strategy, in order to characterize its performance in terms of secondary level control objectives as power sharing and mean voltage regulation. Based on existing consensus control strategies, the novelty of this approach relays on the possibility of comparing the performance of different controllers through numeric indicators. Furthermore, the chosen control strategy is not necessarily derived as the Laplacian matrix of an undirected graph. In this way, the proposed strategy can be tuned to achieve optimal behavior in terms of convergence speed, disturbances rejection, or communication links requirements. Furthermore, by doing this we are able to prove that the traditional droop control strategy does not necessarily achieve the desired objectives in mesh topology. Therefore, we focus on the consensus dynamics of the closed loop system, deriving simple test to conclude on its behavior, and to propose a Linear Matrix Inequality (LMI) based procedure to verify the region of voltage deviations at which the control objective can be achieved. Finally, the results of the paper are illustrated through a simulation example. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： DC micro grids Secondary distributed control consensus algorithms Power sharing Mean voltage regulation Linear matrix inequalities (LMI)

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Unfolding the blockchain era: Timeline, evolution, types and real-world applications

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JOURNAL OF NETWORK AND COMPUTER APPLICATIONS 2022年第0期207卷

作者： Arooj, Ansif Farooq, Muhammad Shoaib Umer, Tariq Univ Educ Div Sci & Technol Lahore Pakistan Univ Management & Technol Lahore Pakistan COMSATS Univ Lahore Pakistan

Blockchain technology is based on a series of time-stamped and decentralized immutable records without third-party involvement. Since the infancy of the term, it has attained attention from academic researchers and industrial contributors, globally. The extensive characteristics of blockchain have created new investigation domains in multiple industries including finance, medical, education, governance etc. In this study, we have conducted the systematic literature mapping to collect all relevant research in the field of blockchain since the inception of this exclusive paradigm and presented a comprehensive assessment and analysis on the extracted research papers in a systematic manner. We have rigorously reviewed the relevant research papers found in the literature for understanding the state of the art techniques, methodologies and, applications of using blockchain in different industries. Moreover, we also have presented the evolution and future insights on the use of blockchain in several real-world applications and also consolidated the blockchain into different high level technical and applied perspectives.

关键词： Blockchain Block chain consensus algorithms Cryptocurrency Internet of Things Smart contract

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