Research On Marching-on In-time Scheme And The Fast Algorithm Of Time Domain Integral Equation

With the advent of the era of knowledge and economy,knowledge plays an increasingly important role in production and life.The technology of knowledge sharing is based on blockchain and knowledge sharing has become a current research priority,the aim of which is to make knowledge and information interrelate with each other.Based on knowledge sharing,the sharing network usually has wide geographical distribution and complex network conditions with the high demand for efficiency and security.However,most of the consensus algorithms for current blockchain are based on the design of synchronous or semi-synchronous network assumption.Such consensus algorithms cannot solve the problems of network delay and cannot guarantee scalability and security at the same time,so it is difficult to apply blockchain-based knowledge sharing with a desirable result.This thesis aims at enhancing the adaptability of asynchronous environment and improving the security of sharding blockchain in a knowledge-sharing environment.The thesis puts forward an improved Dumbo algorithm based on DAG and a reputation-based self-adaptive sharding algorithm.The main research directions and innovations are as follows:(1)In order to solve the problems of insufficient support for asynchronous network environment and low efficiency of asynchronous consensus algorithm,this thesis proposes an improved Dumbo algorithm based on DAG.The improved algorithm optimizes the Dumbo consensus process,allows the blockchain to run in parallel in the consensus stage,and uses the book structure based on directed acyclic graph to record the new blocks generated in parallel.In order to speed up the detection of conflict transactions in directed acyclic graph ledger and reduce the maintenance cost of blockchain,DAG Dumbo algorithm introduces checkpoints to record the current state of blockchain in DAG network.Dag Dumbo algorithm can make the blockchain adapt to the asynchronous working environment and improve the throughput of consensus algorithm.(2)In order to improve the efficiency of blockchain and solve the problems of security and dynamic network adaptability,the thesis proposes a self-adaptive sharding algorithm which is based on reputation value.The algorithm defines a computing method for nodes credit,and the algorithm provides the method of malicious node exit and fast join for the new node around the node credit.On this basis,the algorithm uses a reputation based cuckoo fragment reorganization method to ensure the security of the Committee in each era.By reducing the number of malicious nodes in the network,the adaptive fragmentation algorithm based on reputation value improves the correct proportion of nodes in the partitioned blockchain,enhances the network anti-attack ability,and improves the resource utilization efficiency of the blockchain in the dynamic network environment.(3)In the thesis,two consensus algorithms are used to build a knowledge sharing platform in which knowledge sharing,query,registration and other basic functions are realized.The experiment proves that the improved consensus algorithm can meet the performance and security requirements in knowledge sharing.