The Internet of Vehicles(IoV)operates in highly dynamic and open network environments and faces serious challenges in secure and real-time authentication and consensus mechanisms.Existing methods often suffer from com...The Internet of Vehicles(IoV)operates in highly dynamic and open network environments and faces serious challenges in secure and real-time authentication and consensus mechanisms.Existing methods often suffer from complex certificate management,inefficient consensus protocols,and poor resilience in high-frequency communication,resulting in high latency,poor scalability,and unstable network performance.To address these issues,this paper proposes a secure and efficient distributed authentication scheme for IoV with reputation-driven consensus and SM9.First,this paper proposes a decentralized authentication architecture that utilizes the certificate-free feature of SM9,enabling lightweight authentication and key negotiation,thereby reducing the complexity of key management.To ensure the traceability and global consistency of authentication data,this scheme also integrates blockchain technology,applying its inherent invariance.Then,this paper introduces a reputation-driven dynamic node grouping mechanism that transparently evaluates and groups’node behavior using smart contracts to enhance network stability.Furthermore,a new RBSFT(Reputation-Based SM9 Friendly-Tolerant)consensus mechanism is proposed for the first time to enhance consensus efficiency by optimizing the PBFT algorithm.RBSFT aims to write authentication information into the blockchain ledger to achieve multi-level optimization of trust management and decision-making efficiency,thereby significantly improving the responsiveness and robustness in high-frequency IoV scenarios.Experimental results show that it excels in authentication,communication efficiency,and computational cost control,making it a feasible solution for achieving IoV security and real-time performance.展开更多
To improve the overall magnetic properties of Sm(CoFeCuZr)zsintered magnets,a dual-alloy sintering process that involves mixing high-iron,low-copper powders with low-iron,high-copper powders was systematically inve...To improve the overall magnetic properties of Sm(CoFeCuZr)zsintered magnets,a dual-alloy sintering process that involves mixing high-iron,low-copper powders with low-iron,high-copper powders was systematically investigated.The results demonstrate that this method significantly improves the Cu-lean phenomenon at the grain boundaries,achieves multiscale uniform microstructures,greatly enhances the pinning field strength,and ultimately produces a high-performance dual-alloy magnet with a maximum energy product((BH)max)exceeding 240 kJ/m3and an intrinsic coercivity(Hcj)exceeding 2400 kA/m.In particular,when 35 wt.%of low-iron,high-copper alloy powder is incorporated,the dual-alloy magnet achieves a remanence of 1.13 T,Hcjof 2691.2 kA/m and(BH)maxof 248 kJ/m3.To evaluate the overall magnetic performance,the sum of Hcj(in kA/m)and(BH)max(in kJ/m3)is used as a combined parameter,yielding a value of 2939.2.Compared with single-alloy magnets of the same composition,the dual-alloy sintering process yields magnets with a more uniform elemental distribution and superior magnetic properties.展开更多
Synergistic interactions between small molecules(SMs)and carbon-engine microbes(CEMs)play key roles in soil organic carbon(SOC)accumulation.The SMs(typically<1000 Da),primarily derived from root exudates and polyme...Synergistic interactions between small molecules(SMs)and carbon-engine microbes(CEMs)play key roles in soil organic carbon(SOC)accumulation.The SMs(typically<1000 Da),primarily derived from root exudates and polymer degradation,enhance CEM functions by fueling microbial metabolism via rapid uptake,elevating carbon use efficiency for persistent necromass formation,and enriching mineral-binding and aggregate-forming taxa.展开更多
SmCo7-xMx(M=Cu,Zr,Hf,Si,Ga)intermetallic compounds,with distinctive disordered crystal structure and excellent magnetic performance,are of great importance for application as high-temperature rare-earth permanen...SmCo7-xMx(M=Cu,Zr,Hf,Si,Ga)intermetallic compounds,with distinctive disordered crystal structure and excellent magnetic performance,are of great importance for application as high-temperature rare-earth permanent magnets.In this study,the relationship between the valence electronic structure,structural stability and magnetic and thermal properties of Sm(Co,M)7intermetallic compounds is revealed by using an empirical electron theory of solids and molecules.The structural stability is strongly related to the valence electronic structure that is modulated by doping the third element M into SmCo7.The calculated bond lengths,magnetic moments and Curie temperatures show good agreement with experimental ones.The magnetic moment and Curie temperature strongly depend on the number of 3d magnetic electrons,and can be modulated by mutual electron transformation between 3d magnetic electron and covalence electron.展开更多
域名系统(domain name system,DNS)作为互联网的基础设施,负责将人类可读的域名转换为机器可读的互联网协议(Internet protocol,IP)地址。然而,传统的DNS协议在设计时并未充分考虑安全性,容易受到诸如缓存投毒、中间人攻击等安全威胁。...域名系统(domain name system,DNS)作为互联网的基础设施,负责将人类可读的域名转换为机器可读的互联网协议(Internet protocol,IP)地址。然而,传统的DNS协议在设计时并未充分考虑安全性,容易受到诸如缓存投毒、中间人攻击等安全威胁。域名系统安全扩展(DNS security extensions,DNSSEC)通过引入数字签名机制,确保DNS响应的完整性和真实性,能够有效提升DNS系统的安全性,从而有效防止这些攻击。DNSSEC支持多种密码算法,RFC(request for comments)9563规定了在DNSSEC中使用SM2SM3算法的公钥记录、签名记录格式以及算法号。为推广国家商用密码(Shang Mi,SM)算法在DNSSEC领域的应用,本文对基于SM2SM3算法的DNSSEC应用关键问题进行了分析研究并提出解决方案。展开更多
A rational design of Cu distribution is crucial for achieving optimal magnetic properties in Sm2Co17-type magnets.In this study,nanostructured PrO2 powders were employed to induce Cu redistribution at grain b...A rational design of Cu distribution is crucial for achieving optimal magnetic properties in Sm2Co17-type magnets.In this study,nanostructured PrO2 powders were employed to induce Cu redistribution at grain boundaries while preserving the cellular microstructure.The corresponding coercivity(Hcj),remanence(Br),and maximum energy product((BH)max) were significantly enhanced in the 1 wt% PrO2-doped magnet,with improvements of 4.36 kOe,0.22 kGs and 1.1 MGOe,respectively.These results surpass those of most rare-earth-oxide-doped Sm2Co17-type magnets reported to date.Microstructure characterization and micromagnetic simulations confirm that the coarse Cu-rich phase induced by PrO2 doping enhances the pinning strength at grain boundaries,thereby contributing to the observed coercivity enhancement.The(Sm1-xPrx)2Co17 phase exhibits a higher substitution energy barrier at Co sites,which promotes Cu migration toward grain boundaries.Meanwhile,the(Sm1-xPrx)2Co17phase also slightly improves the remanence in the 1 wt% PrO2-doped magnet due to its higher saturation magnetization(Ms).However,excessive PrO2 doping(2 wt%),while further increasing coercivity by 6.45 kOe,adversely affects squareness and remanence.This study demonstrates a viable strategy for fabricating high-performance Sm2Co17-type permanent magnets while enabling efficient utilization of rare-earth Pr oxides.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61762071,Grant No.61163025).
摘要The Internet of Vehicles(IoV)operates in highly dynamic and open network environments and faces serious challenges in secure and real-time authentication and consensus mechanisms.Existing methods often suffer from complex certificate management,inefficient consensus protocols,and poor resilience in high-frequency communication,resulting in high latency,poor scalability,and unstable network performance.To address these issues,this paper proposes a secure and efficient distributed authentication scheme for IoV with reputation-driven consensus and SM9.First,this paper proposes a decentralized authentication architecture that utilizes the certificate-free feature of SM9,enabling lightweight authentication and key negotiation,thereby reducing the complexity of key management.To ensure the traceability and global consistency of authentication data,this scheme also integrates blockchain technology,applying its inherent invariance.Then,this paper introduces a reputation-driven dynamic node grouping mechanism that transparently evaluates and groups’node behavior using smart contracts to enhance network stability.Furthermore,a new RBSFT(Reputation-Based SM9 Friendly-Tolerant)consensus mechanism is proposed for the first time to enhance consensus efficiency by optimizing the PBFT algorithm.RBSFT aims to write authentication information into the blockchain ledger to achieve multi-level optimization of trust management and decision-making efficiency,thereby significantly improving the responsiveness and robustness in high-frequency IoV scenarios.Experimental results show that it excels in authentication,communication efficiency,and computational cost control,making it a feasible solution for achieving IoV security and real-time performance.
基金supported by the National Key Research and Development Program for Young Scientists,China(No.2023YFB3508400)the National Natural Science Foundation of China(Nos.51871005,51931007)+1 种基金the Key Program of Science and Technology Development Project of Beijing Municipal Education Commission of China(No.KZ202010005009)the Program of Top Disciplines Construction in Beijing,China(No.PXM2019_014204_500031)。
摘要To improve the overall magnetic properties of Sm(CoFeCuZr)zsintered magnets,a dual-alloy sintering process that involves mixing high-iron,low-copper powders with low-iron,high-copper powders was systematically investigated.The results demonstrate that this method significantly improves the Cu-lean phenomenon at the grain boundaries,achieves multiscale uniform microstructures,greatly enhances the pinning field strength,and ultimately produces a high-performance dual-alloy magnet with a maximum energy product((BH)max)exceeding 240 kJ/m3and an intrinsic coercivity(Hcj)exceeding 2400 kA/m.In particular,when 35 wt.%of low-iron,high-copper alloy powder is incorporated,the dual-alloy magnet achieves a remanence of 1.13 T,Hcjof 2691.2 kA/m and(BH)maxof 248 kJ/m3.To evaluate the overall magnetic performance,the sum of Hcj(in kA/m)and(BH)max(in kJ/m3)is used as a combined parameter,yielding a value of 2939.2.Compared with single-alloy magnets of the same composition,the dual-alloy sintering process yields magnets with a more uniform elemental distribution and superior magnetic properties.
基金support from the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2023325)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDA28020202 and XDA28110100)+3 种基金the National Key R&D Program of China(Nos.2022YFD1500203 and 2022YFD1500401)the National Natural Science Foundation of China(No.42177332)the China Agriculture Research System(Nos.CARS-03 and CARS-52)the Key Project for Promoting Technology in Inner Mongolia,China(No.NMKJXM202401-01)。
摘要Synergistic interactions between small molecules(SMs)and carbon-engine microbes(CEMs)play key roles in soil organic carbon(SOC)accumulation.The SMs(typically<1000 Da),primarily derived from root exudates and polymer degradation,enhance CEM functions by fueling microbial metabolism via rapid uptake,elevating carbon use efficiency for persistent necromass formation,and enriching mineral-binding and aggregate-forming taxa.
摘要SmCo7-xMx(M=Cu,Zr,Hf,Si,Ga)intermetallic compounds,with distinctive disordered crystal structure and excellent magnetic performance,are of great importance for application as high-temperature rare-earth permanent magnets.In this study,the relationship between the valence electronic structure,structural stability and magnetic and thermal properties of Sm(Co,M)7intermetallic compounds is revealed by using an empirical electron theory of solids and molecules.The structural stability is strongly related to the valence electronic structure that is modulated by doping the third element M into SmCo7.The calculated bond lengths,magnetic moments and Curie temperatures show good agreement with experimental ones.The magnetic moment and Curie temperature strongly depend on the number of 3d magnetic electrons,and can be modulated by mutual electron transformation between 3d magnetic electron and covalence electron.
摘要域名系统(domain name system,DNS)作为互联网的基础设施,负责将人类可读的域名转换为机器可读的互联网协议(Internet protocol,IP)地址。然而,传统的DNS协议在设计时并未充分考虑安全性,容易受到诸如缓存投毒、中间人攻击等安全威胁。域名系统安全扩展(DNS security extensions,DNSSEC)通过引入数字签名机制,确保DNS响应的完整性和真实性,能够有效提升DNS系统的安全性,从而有效防止这些攻击。DNSSEC支持多种密码算法,RFC(request for comments)9563规定了在DNSSEC中使用SM2SM3算法的公钥记录、签名记录格式以及算法号。为推广国家商用密码(Shang Mi,SM)算法在DNSSEC领域的应用,本文对基于SM2SM3算法的DNSSEC应用关键问题进行了分析研究并提出解决方案。
基金financially supported by the fifth batch of major research and development projects in Panxi Experimental Zone(Grant No.2021dfky005).
摘要A rational design of Cu distribution is crucial for achieving optimal magnetic properties in Sm2Co17-type magnets.In this study,nanostructured PrO2 powders were employed to induce Cu redistribution at grain boundaries while preserving the cellular microstructure.The corresponding coercivity(Hcj),remanence(Br),and maximum energy product((BH)max) were significantly enhanced in the 1 wt% PrO2-doped magnet,with improvements of 4.36 kOe,0.22 kGs and 1.1 MGOe,respectively.These results surpass those of most rare-earth-oxide-doped Sm2Co17-type magnets reported to date.Microstructure characterization and micromagnetic simulations confirm that the coarse Cu-rich phase induced by PrO2 doping enhances the pinning strength at grain boundaries,thereby contributing to the observed coercivity enhancement.The(Sm1-xPrx)2Co17 phase exhibits a higher substitution energy barrier at Co sites,which promotes Cu migration toward grain boundaries.Meanwhile,the(Sm1-xPrx)2Co17phase also slightly improves the remanence in the 1 wt% PrO2-doped magnet due to its higher saturation magnetization(Ms).However,excessive PrO2 doping(2 wt%),while further increasing coercivity by 6.45 kOe,adversely affects squareness and remanence.This study demonstrates a viable strategy for fabricating high-performance Sm2Co17-type permanent magnets while enabling efficient utilization of rare-earth Pr oxides.