scholarly journals Improved PBFT Algorithm For High-Frequency Trading Scenarios of Alliance Blockchain

2022 ◽  
Author(s):  
Song Tang ◽  
Zhiqiang Wang ◽  
Jian Jiang ◽  
Suli Ge ◽  
GaiFang Tan
Keyword(s):  
High Frequency ◽  
Communication Overhead ◽  
Byzantine Fault Tolerance ◽  
Consensus Process ◽  
Network Nodes ◽  
Consensus Algorithms ◽  
Blockchain Technology ◽  
Information Interaction ◽  
Simple Selection ◽  
Selection Of

Abstract With the continuous development of blockchain technology and the emergence of application scenarios, consensus algorithms are still the bottleneck restricting the number of network nodes and data writing efficiency that blockchain can support. How to improve the performance of alliance blockchains safely and efficiently has become an urgent problem to be solved at present. For the practical Byzantine fault tolerance algorithm (PBFT) commonly used in alliance blockchains, there are some problems, such as large communication overhead, simple selection of master nodes, and inability to expand and exit nodes dynamically in the network. This paper proposes an improved algorithm tPBFT (trust-based practical Byzantine algorithm), which is suitable for the high-frequency transaction scenario of alliance chains and introduces a trust interest scoring mechanism between network nodes to adjust the list of consensus nodes dynamically, simplify the PBFT consensus process and reduce the interaction overhead between network nodes. Theoretical analysis and experiments show that the improved tPBFT algorithm can effectively reduce the amount of information interaction between nodes, improve consensus efficiency and support more network nodes.

scholarly journals Improve PBFT Based on Hash Ring

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Wang Zhong ◽  
Xiandong Zheng ◽  
Wenlong Feng ◽  
Mengxing Huang ◽  
Siling Feng
Keyword(s):  
Fault Tolerance ◽  
Sharp Increase ◽  
Communication Complexity ◽  
Random Selection ◽  
Byzantine Fault Tolerance ◽  
Consensus Process ◽  
Frequent Switching ◽  
Proper Operation ◽  
Determination Mechanism ◽  
Selection Of

Aiming at the problems of practical Byzantine fault tolerance (PBFT) algorithm, such as high communication complexity, frequent switching views because of Byzantine node become primary nodes and random selection of primary node, HR-PBFT algorithm is proposed. First, the HR-PBFT algorithm uses a hash ring to group nodes, which ensures the randomness and fairness of the grouping. Then, a dual-view mechanism is used in the consensus process, where the first layer node maintains the primary view and the second layer node maintains the secondary view to ensure the proper operation of the algorithm. Finally, the Byzantine node determination mechanism is introduced to evaluate the node status according to the node behavior in the consensus process, improve the reliability of primary node selection, and reduce the frequency of view changes. The experimental results show that the optimized HR-PBFT algorithm can effectively improve the problem of the sharp increase in the number of communications caused by the increase in the number of nodes in the network and prevent frequent view changes.

scholarly journals A Coordination Technique for Improving Scalability of Byzantine Fault-Tolerant Consensus

2020 ◽  
Vol 10 (21) ◽  
pp. 7609
Author(s):  
Jungwon Seo ◽  
Deokyoon Ko ◽  
Suntae Kim ◽  
Sooyong Park
Keyword(s):  
Fault Tolerance ◽  
Performance Improvement ◽  
Fault Tolerant ◽  
The Other ◽  
Consensus Algorithm ◽  
Byzantine Fault Tolerance ◽  
Consensus Process ◽  
Consensus Algorithms ◽  
Byzantine Fault ◽  
Research Questions

Among various consensus algorithms, the Byzantine Fault Tolerance (BFT)-based consensus algorithms are broadly used for private blockchain. However, as BFT-based consensus algorithms are structured for all participants to take part in a consensus process, a scalability issue becomes more noticeable. In this approach, we introduce a consensus coordinator to execute a conditionally BFT-based consensus algorithm by classifying transactions. Transactions are divided into equal and unequal transactions. Moreover, unequal transactions are divided again and classified as common and trouble transactions. After that, a consensus algorithm is only executed for trouble transactions, and BFT-based consensus algorithms can achieve scalability. For evaluating our approach, we carried out three experiments in response to three research questions. By applying our approach to PBFT, we obtained 4.75 times better performance than using only PBFT. In the other experiment, we applied our approach to IBFT of Hyperledger Besu, and our result shows a 61.81% performance improvement. In all experiments depending on the change of the number of blockchain nodes, we obtained the better performance than original BFT-based consensus algorithms; thus, we can conclude that our approach improved the scalability of original BFT-based consensus algorithms. We also showed a correlation between performance and trouble transactions associated with transaction issue intervals and the number of blockchain nodes.

scholarly journals MedShard: Electronic Health Record Sharing Using Blockchain Sharding

2021 ◽  
Vol 13 (11) ◽  
pp. 5889
Author(s):  
Faiza Hashim ◽  
Khaled Shuaib ◽  
Farag Sallabi
Keyword(s):  
Healthcare System ◽  
Small Groups ◽  
Network Performance ◽  
Communication Overhead ◽  
Privacy And Security ◽  
Health Records ◽  
Medical Practitioners ◽  
Blockchain Technology ◽  
Simulation Results ◽  
Electronic Health

Electronic health records (EHRs) are important assets of the healthcare system and should be shared among medical practitioners to improve the accuracy and efficiency of diagnosis. Blockchain technology has been investigated and adopted in healthcare as a solution for EHR sharing while preserving privacy and security. Blockchain can revolutionize the healthcare system by providing a decentralized, distributed, immutable, and secure architecture. However, scalability has always been a bottleneck in blockchain networks due to the consensus mechanism and ledger replication to all network participants. Sharding helps address this issue by artificially partitioning the network into small groups termed shards and processing transactions parallelly while running consensus within each shard with a subset of blockchain nodes. Although this technique helps resolve issues related to scalability, cross-shard communication overhead can degrade network performance. This study proposes a transaction-based sharding technique wherein shards are formed on the basis of a patient’s previously visited health entities. Simulation results show that the proposed technique outperforms standard-based healthcare blockchain techniques in terms of the number of appointments processed, consensus latency, and throughput. The proposed technique eliminates cross-shard communication by forming complete shards based on “the need to participate” nodes per patient.

scholarly journals Interannual modulation of extratropical high frequency variability

1997 ◽  
Vol 40 (4) ◽  
Author(s):  
R. Caballero
Keyword(s):  
Normal Mode ◽  
Time Scales ◽  
High Frequency ◽  
Spherical Geometry ◽  
Simple Explanation ◽  
Space And Time ◽  
High Frequency Variability ◽  
Hemisphere Winter ◽  
Selection Of

A simple explanation is presented for the observed interannual changes in the dominant space and time scales of Northem Hemisphere winter extratropical high frequency variability. It is found that such changes can suc- cessfully be predicted by linearizing a 2-level quasi-geostrophic mode] in spherical geometry around the ob- served zona] mean states. The mechanisms responsible for the selection of the most unstable normal mode are investigated.

A loyalty program based on Waves blockchain and mobile phone interactions

2020 ◽  
Vol 35 ◽  
Author(s):  
Luis J. Dominguez Perez ◽  
Luis Ibarra ◽  
García-Fernández Alejandro ◽  
Agustín Rumayor ◽  
Carlos Lara-Alvarez
Keyword(s):  
Mobile Phone ◽  
Credit Cards ◽  
Customer Retention ◽  
Loyalty Program ◽  
Specific Data ◽  
Blockchain Technology ◽  
Selection Of

Abstract Loyalty cards programs have been used by retailers to increase customer retention. Loyality cards provide means to identify a particular customer and to collect customer-specific data, thus enabling individualized marketing; however, operating a loyalty program is complicated for retailers since they require to manage balances, collections, and transfers of customers. This is exactly the same problem the retailers were facing before credit cards were readily available. A new problem is that customers now have too many cards, customers may forget, or even deliberately decide to carry only a selection of their cards. This paper proposes a loyalty program based on a blockchain that does not require a physical card for identifying customers as it associates customers to their phone numbers, since nowadays people always carry their phone. In this perspective, companies can reduce overhead costs associated to managing the loyalty program. This paper reviews the technology required and describes the implementation of a loyalty program based on blockchains. Finally, it also enumerates the reasons for choosing the blockchain technology for this application.

scholarly journals Design of Secure Protocol for Cloud-Assisted Electronic Health Record System Using Blockchain

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2913 ◽  
Author(s):  
MyeongHyun Kim ◽  
SungJin Yu ◽  
JoonYoung Lee ◽  
YoHan Park ◽  
YoungHo Park
Keyword(s):  
Cloud Computing ◽  
Electronic Health Record ◽  
Medical Service ◽  
Mutual Authentication ◽  
Internet Security ◽  
Communication Overhead ◽  
Health Record ◽  
Blockchain Technology ◽  
Secure Protocol ◽  
Electronic Health

In the traditional electronic health record (EHR) management system, each medical service center manages their own health records, respectively, which are difficult to share on the different medical platforms. Recently, blockchain technology is one of the popular alternatives to enable medical service centers based on different platforms to share EHRs. However, it is hard to store whole EHR data in blockchain because of the size and the price of blockchain. To resolve this problem, cloud computing is considered as a promising solution. Cloud computing offers advantageous properties such as storage availability and scalability. Unfortunately, the EHR system with cloud computing can be vulnerable to various attacks because the sensitive data is sent over a public channel. We propose the secure protocol for cloud-assisted EHR system using blockchain. In the proposed scheme, blockchain technology is used to provide data integrity and access control using log transactions and the cloud server stores and manages the patient’s EHRs to provide secure storage resources. We use an elliptic curve cryptosystems (ECC) to provide secure health data sharing with cloud computing. We demonstrate that the proposed EHR system can prevent various attacks by using informal security analysis and automated validation of internet security protocols and applications (AVISPA) simulation. Furthermore, we prove that the proposed EHR system provides secure mutual authentication using BAN logic analysis. We then compare the computation overhead, communication overhead, and security properties with existing schemes. Consequently, the proposed EHR system is suitable for the practical healthcare system considering security and efficiency.

Observations of Meteors using an over-the-horizon Radar

1989 ◽  
Vol 8 (1) ◽  
pp. 88-93 ◽  
Author(s):  
R. M. Thomas ◽  
D. J. Netherway
Keyword(s):  
Signal Processing ◽  
High Frequency ◽  
Meteor Shower ◽  
Upper Atmosphere ◽  
High Frequency Band ◽  
Meteor Detection ◽  
Signal Environment ◽  
Frequency Management ◽  
Sporadic Meteors ◽  
Selection Of

AbstractWhen metre wavelength radars were first operated in the 1940s, echoes were obtained which could be attributed to backscatter from ionised trains produced by the ablation of meteroids in the upper atmosphere at altitudes near 100 km. Modern over-the-horizon skywave radars operating in the HF (High Frequency) band employ digital techniques for both radar control and signal processing and are aided by frequency management subsystems for the selection of appropriate frequencies for meteor detection based on real-time monitoring of the HF signal environment.This paper describes the results of using such a radar for meteor observations. We report the detection of the Eta Aquarid meteor shower and demonstrate that a large increase in the echo rate due to sporadic meteors is obtained as frequencies are reduced below 15 MHz and the underdense echo ceiling rises in altitude. Finally, we present preliminary observations of highly Doppler shifted echoes which travel at meteoric velocities and which we identify as meteor ‘head echoes’.

scholarly journals Exploiting Weak Ties in Incomplete Network Datasets Using Simplified Graph Convolutional Neural Networks

2020 ◽  
Vol 2 (2) ◽  
pp. 125-146 ◽  
Author(s):  
Neda H. Bidoki ◽  
Alexander V. Mantzaris ◽  
Gita Sukthankar
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Centrality Measures ◽  
Weak Ties ◽  
Original Graph ◽  
Convolutional Network ◽  
Strong Ties ◽  
Network Nodes ◽  
Node Removal ◽  
Selection Of

This paper explores the value of weak-ties in classifying academic literature with the use of graph convolutional neural networks. Our experiments look at the results of treating weak-ties as if they were strong-ties to determine if that assumption improves performance. This is done by applying the methodological framework of the Simplified Graph Convolutional Neural Network (SGC) to two academic publication datasets: Cora and Citeseer. The performance of SGC is compared to the original Graph Convolutional Network (GCN) framework. We also examine how node removal affects prediction accuracy by selecting nodes according to different centrality measures. These experiments provide insight for which nodes are most important for the performance of SGC. When removal is based on a more localized selection of nodes, augmenting the network with both strong-ties and weak-ties provides a benefit, indicating that SGC successfully leverages local information of network nodes.

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