• Title, Summary, Keyword: Consensus Analysis

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Observer-based Distributed Consensus Algorithm for Multi-agent Systems with Output Saturations

  • Lim, Young-Hun;Lee, Gwang-Seok
    • Journal of information and communication convergence engineering
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    • v.17 no.3
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    • pp.167-173
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    • 2019
  • This study investigates the problem of leader-following consensus for multi-agent systems with output saturations. This study assumes that the agents are described as a neutrally stable system, and the leader agent generates the bounded trajectory within the saturation level. Then, the objective of the leader-following consensus is to track the trajectory of the leader by exchanging information with neighbors. To solve this problem, we propose an observer-based distributed consensus algorithm. Then, we provide a consensus analysis by applying the Lyapunov stability theorem and LaSalle's invariance principle. The result shows that the agents achieve the leader-following consensus in a global sense. Moreover, we can achieve the consensus by choosing any positive control gain. Finally, we perform a numerical simulation to demonstrate the validity of the proposed algorithm.

Group Average-consensus and Group Formation-consensus for First-order Multi-agent Systems (일차 다개체 시스템의 그룹 평균 상태일치와 그룹 대형 상태일치)

  • Kim, Jae Man;Park, Jin Bae;Choi, Yoon Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.20 no.12
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    • pp.1225-1230
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    • 2014
  • This paper investigates the group average-consensus and group formation-consensus problems for first-order multi-agent systems. The control protocol for group consensus is designed by considering the positive adjacency elements. Since each intra-group Laplacian matrix cannot be satisfied with the in-degree balance because of the positive adjacency elements between groups, we decompose the Laplacian matrix into an intra-group Laplacian matrix and an inter-group Laplacian matrix. Moreover, average matrices are used in the control protocol to analyze the stability of multi-agent systems with a fixed and undirected communication topology. Using the graph theory and the Lyapunov functional, stability analysis is performed for group average-consensus and group formation-consensus, respectively. Finally, some simulation results are presented to validate the effectiveness of the proposed control protocol for group consensus.

Comparative Analysis of Blockchain Systems According to Validator Set Formation Method (검증자 집합 형성 방법에 따른 블록체인 시스템 비교 분석)

  • Kim, Sam-Taek
    • Journal of the Korea Convergence Society
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    • v.10 no.11
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    • pp.41-46
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    • 2019
  • Recently, the Byzantine Fault Tolerance(BFT) family of consensus algorithms has been attracting attention as the problems of the Proof-of-work (PoW) blockchain consensus algorithms result in energy waste and lack of scalability. One of the great features of the PBFT family consensus algorithms is the formation of a set of validators and consensus within them. In this paper, we compared and analyzed the scalability, targeted attackability, and civil attackability of Algorand, Stellar, and EOS validator set formation methods among BFT family consensus algorithms. Also, we found the problems of each verifier formation method through data analysis, and the consensus algorithms showed that the centralization phenomenon that the few powerful nodes dominate the whole system in common.

MMOG User Participation Based Decentralized Consensus Scheme and Proof of Participation Analysis on the Bryllite Blockchain System

  • Yun, Jusik;Goh, Yunyeong;Chung, Jong-Moon;Kim, OkSeok;Shin, SangWoo;Choi, Jin;Kim, Yoora
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.8
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    • pp.4093-4107
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    • 2019
  • Proof of Work (PoW) based blockchains have limitations in throughput, time consumption, and energy efficiency. In these systems, a miner will consume significant time and resources to obtain a reward for contributing to the blockchain. To overcome these limitations, recent research on blockchains are focused on accelerating the speed, scalability, and enhancing the security level. By enhancing specific procedures of blockchain system, the level of data integrity supported by the blockchain can become more robust, and efficient. In this paper, a new blockchain consensus model based on the Bryllite Consensus Protocol (BCP) is proposed to support a hyper-connected massively multiplayer online game (MMOG) ecosystem. The BCP scheme enables users to participate directly in new consensus processes through a Proof of Participation (PoP) algorithm. In this model, the consensus algorithm has a simpler form while maintaining high security level. In addition, because the BCP scheme gives users an equal chance to make a contribution to the blockchain, rewards are distributed in an equal fashion, which motivates user participation. The analysis of the proposed scheme is applied to the Bryllite consortium blockchain system (homed in Hong Kong), which is a new blockchain network developed for international game industries, gamers, and game events.

A newly developed consensus polymerase chain reaction to detect Mycoplasma species using 16S ribosomal RNA gene

  • Hong, Sunhwa;Park, Sang-Ho;Chung, Yung-Ho;Kim, Okjin
    • Korean Journal of Veterinary Service
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    • v.35 no.4
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    • pp.289-294
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    • 2012
  • Mycoplasmas are highly fastidious bacteria, difficult to culture and slow growing. Infections with Mycoplasma species can cause a variety of problems in living organisms and in vitro cell cultures. In this study, we investigated the usefulness of a genus-specific consensus PCR analysis method to detect Mycoplasma species. The developed consensus primer pairs MycoF and MycoR were designed specifically to amplify the 16S ribosomal RNA gene (rRNA) of Mycoplasma species by the optimized PCR system. The developed consensus PCR system effectively amplified 215 bp of Mycoplasma genus-specific region of 16S rRNA. In conclusion, we recommend this consensus PCR for monitoring Mycoplasma species in animals, human and cell culture system.

A Comparative Study on the Various Perspectives on the Nature of Science through Textbook Analysis Centering on the Consensus View, Features of Science, and Family Resemblance Approach (교과서 분석을 통한 과학의 본성에 대한 여러 관점의 비교 -전통적 접근, 과학의 특성, 가족 유사성 관점을 중심으로-)

  • Jho, Hunkoog
    • Journal of The Korean Association For Science Education
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    • v.39 no.5
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    • pp.681-694
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    • 2019
  • This study intends to delineate the characteristics of various perspectives on the nature of science (NOS) through the textbook analysis. Thus, centering on a science textbook called Science Laboratory Experiments, this study analyzes the elements of the NOS from three different perspectives: the consensus view, features of science (FOS), and family resemblance approach (FRA). While the consensus view highlights the similar elements of the NOS across the topics, the FOS is concerned about empirical ways for doing science. The FRA rather focuses on socio-cultural aspects of science activities. While the consensus view is useful to reify the features of the NOS, the FRA helps to understand science from various viewpoints. Regarding the philosophical account for three perspectives, all of them are ambiguous to some extent. The consensus view holds contradictory dispositions e.g., relativism vs. (post-)positivism, and critical realism and instrumentalism. The FOS supports empirical tradition but cannot effectively cope with the anomalous situation. The FRA is useful to show up the ways of science in both microscopic (personal) and macroscopic (social) viewpoints. However, the broader concept about science may mislead understanding of the NOS. Consequently, this study provides some implication for improving the framework of the NOS and teaching the NOS in the classroom.

LQ Inverse Optimal Consensus Protocol for Continuous-Time Multi-Agent Systems and Its Application to Formation Control (연속시간 다개체 시스템에 대한 LQ-역최적 상태일치 프로토콜 및 군집제어 응용)

  • Lee, Jae Young;Choi, Yoon Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.20 no.5
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    • pp.526-532
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    • 2014
  • In this paper, we present and analyze a LQ (Linear Quadratic) inverse optimal state-consensus protocol for continuous-time multi-agent systems with undirected graph topology. By Lyapunov analysis of the state-consensus error dynamics, we show the sufficient conditions on the algebraic connectivity of the graph to guarantee LQ inverse optimality and closed-loop stability. A more relaxed stability condition is also provided in terms of the algebraic connectivity. Finally, a formation control protocol for multiple mobile robots is proposed based on the target LQ inverse optimal consensus protocol, and the simulation results are provided to verify the performance of the proposed LQ inverse formation control method.

Consensus-Building on Most Important Problems: Analysis of Gallup Data from 1991 to 2006 (중요한 사회적 의제(MP)에 대한 공적 합의: $1991{\sim}2006$년의 갤럽데이터 분석)

  • Ha, Sung-Tae;Cho, Eui-Hyun
    • Korean journal of communication and information
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    • v.41
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    • pp.41-74
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    • 2008
  • Based on the theory of news media's agenda-setting function, this study analyzed Korean public's most important problems (MIP) and the degree of public consensus on the importance of those MIP's. The analysis was done in terms of both time and social strata. According to the findings, economy, social welfare, and political issues were in the for tier of the MIP list. The analysis of issue diversity (H-statistic) also demonstrated a relatively high degree of agenda consensus among Korean public despite some fluctuation in the consensus level, which appears to be higher than that among the American public. A decrease in the degree of agenda consensus with the passage of time appealed to be a general phenomenon across diverse social strata. However, the degrees of consensus-building were different in light of education, socioeconomic status, and the size of residential area. Those who are more educated, have more economic power, and live in a larger city had more chances to experience agenda consensus. These results seem to be basically attributable to the presumed positive relationship between these demographic variables and media exposure. The different degrees of public consensus according to the different levels of those demographic variables suggest that a closer investigation into the various influences on the importance of public issues among the respondents should be done in future studies.

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Performance Improvement of Distributed Consensus Algorithms for Blockchain through Suggestion and Analysis of Assessment Items (평가항목 제안 및 분석을 통한 블록체인 분산합의 알고리즘 성능 개선)

  • Kim, Do Gyun;Choi, Jin Young;Kim, Kiyoung;Oh, Jintae
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.41 no.4
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    • pp.179-188
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    • 2018
  • Recently, blockchain technology has been recognized as one of the most important issues for the 4th Industrial Revolution which can be represented by Artificial Intelligence and Internet of Things. Cryptocurrency, named Bitcoin, was the first successful implementation of blockchain, and it triggered the emergence of various cryptocurrencies. In addition, blockchain technology has been applied to various applications such as finance, healthcare, manufacturing, logistics as well as public services. Distributed consensus algorithm is an essential component in blockchain, and it enables all nodes belonging to blockchain network to make an agreement, which means all nodes have the same information. For example, Bitcoin uses a consensus algorithm called Proof-of-Work (PoW) that gives possession of block generation based on the computational volume committed by nodes. However, energy consumption for block generation in PoW has drastically increased due to the growth of computational performance to prove the possession of block. Although many other distributed consensus algorithms including Proof-of-Stake are suggested, they have their own advantages and limitations, and new research works should be proposed to overcome these limitations. For doing this, above all things, we need to establish an evaluation method existing distributed consensus algorithms. Based on this motivation, in this work, we suggest and analyze assessment items by classifying them as efficiency and safety perspectives for investigating existing distributed consensus algorithms. Furthermore, we suggest new assessment criteria and their implementation methods, which can be used for a baseline for improving performance of existing distributed consensus algorithms and designing new consensus algorithm in future.

Harmony through Holistic Engagement: An Emic Model of Greater East Asian Regionalism

  • von Feigenblatt, Otto F.
    • Journal of Contemporary Eastern Asia
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    • v.12 no.2
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    • pp.61-87
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    • 2013
  • This study applies grounded theory to develop an emic substantive theory of regional integration in Greater East Asia. The role of norms and policies is explored through discursive content analysis of a wide theoretical sample of official elite policy statements dealing with regionalism and related policy areas. A resulting model of regional integration titled "Harmony through Holistic Engagement" is then discussed in relation to the etic consensus on the phenomenon. The study concludes that the etic consensus on the nature of regional integration in Greater East Asia greatly differs from the results of an emic approach and thus reflects a normative consensus rather than a descriptive reality.