Blockchain systems are challenged by the so-called Trilemma tradeoff:
decentralization, scalability and security. Infrastructure and node
configuration, choice of the Consensus Protocol and complexity of the
application transactions are cited amongst the factors that affect the
tradeoffs balance. Given that Blockchains are complex, dynamic dynamic systems,
a dynamic approach to their management and reconfiguration at runtime is deemed
necessary to reflect the changes in the state of the infrastructure and
application. This paper introduces the utilisation of Digital Twins for this
purpose. The novel contribution of the paper is design of a framework and
conceptual architecture of a Digital Twin that can assist in maintaining the
Trilemma tradeoffs of time critical systems. The proposed Digital Twin is
illustrated via an innovative approach to dynamic selection of Consensus
Protocols. Simulations results show that the proposed framework can effectively
support the dynamic adaptation and management of the Blockchain

该论文介绍了利用数字孪生技术来帮助区块链系统的动态管理和重组，通过动态选择共识协议等方式维护区块链系统的性能平衡，模拟结果表明该数字孪生架构能够有效支持区块链的动态适应和管理。

区块链系统的动态管理数字孪生

Digital Twins for Dynamic Management of Blockchain Systems

Since the inception of Bitcoin, cryptocurrencies and the underlying
blockchain technology have attracted an increasing interest from both academia
and industry. Among various core components, consensus protocol is the defining
technology behind the security and performance of blockchain. From incremental
modifications of Nakamoto consensus protocol to innovative alternative
consensus mechanisms, many consensus protocols have been proposed to improve
the performance of the blockchain network itself or to accommodate other
specific application needs.
In this survey, we present a comprehensive review and analysis on the
state-of-the-art blockchain consensus protocols. To facilitate the discussion
of our analysis, we first introduce the key definitions and relevant results in
the classic theory of fault tolerance which help to lay the foundation for
further discussion. We identify five core components of a blockchain consensus
protocol, namely, block proposal, block validation, information propagation,
block finalization, and incentive mechanism. A wide spectrum of blockchain
consensus protocols are then carefully reviewed accompanied by algorithmic
abstractions and vulnerability analyses. The surveyed consensus protocols are
analyzed using the five-component framework and compared with respect to
different performance metrics. These analyses and comparisons provide us new
insights in the fundamental differences of various proposals in terms of their
suitable application scenarios, key assumptions, expected fault tolerance,
scalability, drawbacks and trade-offs. We believe this survey will provide
blockchain developers and researchers a comprehensive view on the
state-of-the-art consensus protocols and facilitate the process of designing
future protocols.

本文综述现有区块链共识协议，以五个核心组件为框架，分别为区块提议、区块验证、信息传播、区块最终确认和激励机制，分别从算法抽象和安全漏洞等角度进行评估和比较，为区块链开发者和研究人员提供了全面的现状展望和设计参考。

区块链网络分布式共识协议综述

A Survey of Distributed Consensus Protocols for Blockchain Networks

Fabric is a modular and extensible open-source system for deploying and
operating permissioned blockchains and one of the Hyperledger projects hosted
by the Linux Foundation (www.hyperledger.org).
Fabric is the first truly extensible blockchain system for running
distributed applications. It supports modular consensus protocols, which allows
the system to be tailored to particular use cases and trust models. Fabric is
also the first blockchain system that runs distributed applications written in
standard, general-purpose programming languages, without systemic dependency on
a native cryptocurrency. This stands in sharp contrast to existing blockchain
platforms that require "smart-contracts" to be written in domain-specific
languages or rely on a cryptocurrency. Fabric realizes the permissioned model
using a portable notion of membership, which may be integrated with
industry-standard identity management. To support such flexibility, Fabric
introduces an entirely novel blockchain design and revamps the way blockchains
cope with non-determinism, resource exhaustion, and performance attacks.
This paper describes Fabric, its architecture, the rationale behind various
design decisions, its most prominent implementation aspects, as well as its
distributed application programming model. We further evaluate Fabric by
implementing and benchmarking a Bitcoin-inspired digital currency. We show that
Fabric achieves end-to-end throughput of more than 3500 transactions per second
in certain popular deployment configurations, with sub-second latency, scaling
well to over 100 peers.

Fabric 是一个模块化且可扩展的开源系统，用于部署和运营权限块链（区块链核心技术）和 Hyperledger 项目的一部分。它支持模块化共识协议，可以针对特定的用例和信任模型进行定制。Fabric 是第一个在标准通用编程语言中运行分布式应用程序的区块链系统，无需原生加密货币。