In permissioned blockchain networks,the Proof of Authority(PoA)consensus,which uses the election of authorized nodes to validate transactions and blocks,has beenwidely advocated thanks to its high transaction throughp...In permissioned blockchain networks,the Proof of Authority(PoA)consensus,which uses the election of authorized nodes to validate transactions and blocks,has beenwidely advocated thanks to its high transaction throughput and fault tolerance.However,PoA suffers from the drawback of centralization dominated by a limited number of authorized nodes and the lack of anonymity due to the round-robin block proposal mechanism.As a result,traditional PoA is vulnerable to a single point of failure that compromises the security of the blockchain network.To address these issues,we propose a novel decentralized reputation management mechanism for permissioned blockchain networks to enhance security,promote liveness,and mitigate centralization while retaining the same throughput as traditional PoA.This paper aims to design an off-chain reputation evaluation and an on-chain reputation-aided consensus.First,we evaluate the nodes’reputation in the context of the blockchain networks and make the reputation globally verifiable through smart contracts.Second,building upon traditional PoA,we propose a reputation-aided PoA(rPoA)consensus to enhance securitywithout sacrificing throughput.In particular,rPoA can incentivize nodes to autonomously form committees based on reputation authority,which prevents block generation from being tracked through the randomness of reputation variation.Moreover,we develop a reputation-aided fork-choice rule for rPoA to promote the network’s liveness.Finally,experimental results show that the proposed rPoA achieves higher security performance while retaining transaction throughput compared to traditional PoA.展开更多
1.Introduction Carbon neutrality has emerged as a global goal due to its pivotal role in addressing the challenges of global climate change.Before the United Nations Climate Summit was held in November 2020,124 countr...1.Introduction Carbon neutrality has emerged as a global goal due to its pivotal role in addressing the challenges of global climate change.Before the United Nations Climate Summit was held in November 2020,124 countries promised to reach net-zero emissions[1].Solar energy is one of the important renewable energy sources that significantly curtail carbon emissions originating from fossil fuels.展开更多
As one of the most valuable technologies,blockchains have received extensive attention from researchers and industry circles and are widely applied in various scenarios.However,data on a blockchain cannot be deleted.A...As one of the most valuable technologies,blockchains have received extensive attention from researchers and industry circles and are widely applied in various scenarios.However,data on a blockchain cannot be deleted.As a result,it is impossible to clean invalid and sensitive data and correct erroneous data.This,to a certain extent,hinders the application of blockchains in supply chains and Internet of Things.To address this problem,this study presents a deletable and modifiable blockchain scheme(DMBlockChain)based on record verification trees(RVTrees)and the multisignature scheme.(1)In this scheme,an RVTree structure is designed and added to the block structure.The RVTree can not only ensure that a record is true and valid but,owing to its unique binary structure,also verify whether modification and deletion requests are valid.(2)In DMBlockChain,the multisignature mechanism is also introduced.This mechanism requires the stakeholders’signatures for each modification or deletion request and thus ensures that a record will not be modified arbitrarily.A user’s request is deemed valid only if it is dually verified by the RVTree and the multisignature mechanism.The analysis finds that DMBlockChain can provide a secure and valid means for modifying and deleting records in a block while ensuring the integrity of the block and that DMBlockChain can effectively save space in some scenarios that require frequent records modification.展开更多
At present,the mortality rate and disability rate caused by cardiovascular and cerebrovascular diseases are very high in China.Individuals with refractory hypertension are at a greater risk of developing chronic kidne...At present,the mortality rate and disability rate caused by cardiovascular and cerebrovascular diseases are very high in China.Individuals with refractory hypertension are at a greater risk of developing chronic kidney disease,heart failure,stroke and myocardial infarction.Therefore,how to effectively control blood pressure and identify the cause of refractory hypertension is a problem that medical workers need to solve,and it is also the key to prevent cardiovascular disease.In recent years,the government actively supports the development of traditional Chinese medicine.Since the curative effect of traditional Chinese medicine is recognized by the public,the prospect of traditional Chinese medicine in the prevention and treatment of refractory hypertension is considerable,and it is expected to become the main key research direction in the future.展开更多
High-performance active terahertz modulators as the indispensable core components are of great importance for the next generation communication technology.However,they currently suffer from the tradeoff between modula...High-performance active terahertz modulators as the indispensable core components are of great importance for the next generation communication technology.However,they currently suffer from the tradeoff between modulation depth and speed.Here,we introduce two-dimensional(2D)tellurium(Te)nanofilms with the unique structure as a new class of optically controlled terahertz modulators and demonstrate their integrated heterojunctions can successfully improve the device performances to the optimal and applicable levels among the existing all-2D broadband modulators.Further photoresponse measurements confirm the significant impact of the stacking order.We first clarify the direction of the substrate-induced electric field through first-principles calculations and uncover the unusual interaction mechanism in the photoexcited carrier dynamics associated with the charge transfer and interlayer exciton recombination.This advances the fundamental and applicative research of Te nanomaterials in high-performance terahertz optoelectronics.展开更多
基金supported by the Shenzhen Science and Technology Program under Grants KCXST20221021111404010,JSGG20220831103400002,JSGGKQTD20221101115655027,JCYJ 20210324094609027the National KeyR&DProgram of China under Grant 2021YFB2700900+1 种基金the National Natural Science Foundation of China under Grants 62371239,62376074,72301083the Jiangsu Specially-Appointed Professor Program 2021.
文摘In permissioned blockchain networks,the Proof of Authority(PoA)consensus,which uses the election of authorized nodes to validate transactions and blocks,has beenwidely advocated thanks to its high transaction throughput and fault tolerance.However,PoA suffers from the drawback of centralization dominated by a limited number of authorized nodes and the lack of anonymity due to the round-robin block proposal mechanism.As a result,traditional PoA is vulnerable to a single point of failure that compromises the security of the blockchain network.To address these issues,we propose a novel decentralized reputation management mechanism for permissioned blockchain networks to enhance security,promote liveness,and mitigate centralization while retaining the same throughput as traditional PoA.This paper aims to design an off-chain reputation evaluation and an on-chain reputation-aided consensus.First,we evaluate the nodes’reputation in the context of the blockchain networks and make the reputation globally verifiable through smart contracts.Second,building upon traditional PoA,we propose a reputation-aided PoA(rPoA)consensus to enhance securitywithout sacrificing throughput.In particular,rPoA can incentivize nodes to autonomously form committees based on reputation authority,which prevents block generation from being tracked through the randomness of reputation variation.Moreover,we develop a reputation-aided fork-choice rule for rPoA to promote the network’s liveness.Finally,experimental results show that the proposed rPoA achieves higher security performance while retaining transaction throughput compared to traditional PoA.
文摘1.Introduction Carbon neutrality has emerged as a global goal due to its pivotal role in addressing the challenges of global climate change.Before the United Nations Climate Summit was held in November 2020,124 countries promised to reach net-zero emissions[1].Solar energy is one of the important renewable energy sources that significantly curtail carbon emissions originating from fossil fuels.
基金This work was supported by the Scientific and technological project of Henan Province(Grant Nos.202102310340,212102210414)Foundation of University Young Key Teacher of Henan Province(Grant Nos.2019GGJS040,2020GGJS027)+1 种基金Key scientific research projects of colleges and universities in Henan Province(Grant No.21A110005)National Natual Science Foundation of China(61701170).
文摘As one of the most valuable technologies,blockchains have received extensive attention from researchers and industry circles and are widely applied in various scenarios.However,data on a blockchain cannot be deleted.As a result,it is impossible to clean invalid and sensitive data and correct erroneous data.This,to a certain extent,hinders the application of blockchains in supply chains and Internet of Things.To address this problem,this study presents a deletable and modifiable blockchain scheme(DMBlockChain)based on record verification trees(RVTrees)and the multisignature scheme.(1)In this scheme,an RVTree structure is designed and added to the block structure.The RVTree can not only ensure that a record is true and valid but,owing to its unique binary structure,also verify whether modification and deletion requests are valid.(2)In DMBlockChain,the multisignature mechanism is also introduced.This mechanism requires the stakeholders’signatures for each modification or deletion request and thus ensures that a record will not be modified arbitrarily.A user’s request is deemed valid only if it is dually verified by the RVTree and the multisignature mechanism.The analysis finds that DMBlockChain can provide a secure and valid means for modifying and deleting records in a block while ensuring the integrity of the block and that DMBlockChain can effectively save space in some scenarios that require frequent records modification.
文摘At present,the mortality rate and disability rate caused by cardiovascular and cerebrovascular diseases are very high in China.Individuals with refractory hypertension are at a greater risk of developing chronic kidney disease,heart failure,stroke and myocardial infarction.Therefore,how to effectively control blood pressure and identify the cause of refractory hypertension is a problem that medical workers need to solve,and it is also the key to prevent cardiovascular disease.In recent years,the government actively supports the development of traditional Chinese medicine.Since the curative effect of traditional Chinese medicine is recognized by the public,the prospect of traditional Chinese medicine in the prevention and treatment of refractory hypertension is considerable,and it is expected to become the main key research direction in the future.
基金supported by the National Natural Science Foundation of China(Nos.62075142,12074271,12074416,and 12222414)the Youth Innovation Promotion Association of CAS(No.Y2022003).
文摘High-performance active terahertz modulators as the indispensable core components are of great importance for the next generation communication technology.However,they currently suffer from the tradeoff between modulation depth and speed.Here,we introduce two-dimensional(2D)tellurium(Te)nanofilms with the unique structure as a new class of optically controlled terahertz modulators and demonstrate their integrated heterojunctions can successfully improve the device performances to the optimal and applicable levels among the existing all-2D broadband modulators.Further photoresponse measurements confirm the significant impact of the stacking order.We first clarify the direction of the substrate-induced electric field through first-principles calculations and uncover the unusual interaction mechanism in the photoexcited carrier dynamics associated with the charge transfer and interlayer exciton recombination.This advances the fundamental and applicative research of Te nanomaterials in high-performance terahertz optoelectronics.
基金This work has been supported by the National Natural Science Foundation of China （Nos. 61621003, 61422309, 61379092 and 11661141019）, the Strategic Priority Research Program of the Chinese Academy of Sciences （CAS） （XDB13040600） and CAS Frontier Science Research Key Project for Top Young Scientist （QYZDB-SSW-SYS008）.
