We find that tilt and decentration of intraocular lens (IOL) commonly cause visualquality deterioration after cataract surgery. Multiple factors affect IOL tilt anddecentration in the pre-, mid-, and post-operation ph...We find that tilt and decentration of intraocular lens (IOL) commonly cause visualquality deterioration after cataract surgery. Multiple factors affect IOL tilt anddecentration in the pre-, mid-, and post-operation phases. Moreover, the tilt anddecentration of 1-piece IOL are less correlated with internal ocular HOAs thanthose of 3-piece IOL. Aspherical IOLs are more sensitive to decentration or tiltthan spherical IOLs. Furthermore, the optical performance of toric IOLs with anaccurate axis remains stable irrespective of tilt and decentration. The opticalquality of asymmetric multifocal IOLs varies significantly after decentration andtilt in different directions. The image quality enhances or deteriorates in thedirection of the decentered IOL. An extended depth of focus IOL can achievegood visual acuity in the distant, intermediate, and near range. Additionally, itstilt and decentration have less impact on the vision than bifocal and trifocal IOL.This is the first review that compares the effect of IOL tilt and decentration onimage quality for various IOL designs. The result indicates that a deeperunderstanding of tilt and decentration of various IOLs can help achieve a bettervisual effect to visually improve refractive cataract surgery.展开更多
As the geometric center of circular grating does not coincide with the rotation center,the angle measurement error of circular grating is analyzed. Based on the moire fringe equations in decentration condition,the mat...As the geometric center of circular grating does not coincide with the rotation center,the angle measurement error of circular grating is analyzed. Based on the moire fringe equations in decentration condition,the mathematical model of angle measurement error is derived. It is concluded that the decentration between the centre of circular grating and the center of revolving shaft leads to the first-harmonic error of angle measurement. The correctness of the result is proved by experimental data. The method of error compensation is presented,and the angle measurement accuracy of the circular grating is effectively improved by the error compensation.展开更多
· AIM: To evaluate the optical performance of toric intraocular lenses(IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned.· METHODS: Optical performances of...· AIM: To evaluate the optical performance of toric intraocular lenses(IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned.· METHODS: Optical performances of toric T5 and SN60 AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from0° to 90°. The ratio of the modulation transfer function(MTF) between a decentered and a centered IOL(MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance.· RESULTS: Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased,whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentrationratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60 AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60 AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs.· CONCLUSION: Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.展开更多
To investigate the characteristics and associated factors of intraocular lens(IOL)tilt and decentration in pediatric cataract patients undergoing primary IOL implantation and to explore their impact on postoperative o...To investigate the characteristics and associated factors of intraocular lens(IOL)tilt and decentration in pediatric cataract patients undergoing primary IOL implantation and to explore their impact on postoperative optical quality.Methods Children who underwent cataract extraction with posterior capsulotomy,primary anterior vitrectomy,and in-the-bag IOL implantation over 6 months were enrolled.Patient data and ocular biometric parameters were retrieved from electronic files.Retroillumination images were obtained to evaluate capsular outcomes.IOL tilt and decentration were assessed using the swept-source optical coherence tomography,and wavefront aberrations were measured with the OPD-Scan III.Results A total of 125 eyes from 125 patients with a mean age at surgery of 4.74±1.49 years were included.The IOLs demonstrated a mean tilt of 6.02±1.97°toward the temporal direction and a mean decentration of 0.28±0.13〓〓mm toward the superior-temporal direction.Multivariate analysis revealed that shorter axial length(AL;P=0.009)and significant cortical proliferation(P〓〓=〓〓0.021)were associated with greater IOL tilt.In addition,smaller corneal diameter(CD;P=0.008)and incomplete capsulorhexis-IOL overlap(P=0.022)were associated with larger IOL decentration.Patients with IOL tilt≥7°and decentration≥0.40〓〓mm exhibited higher internal total higher-order aberrations(tHOA)and internal astigmatism,both of which were positively correlated with IOL misalignment(all P〓〓<〓〓0.05)Conclusions Shorter AL,smaller CD,significant cortical proliferation,and incomplete capsulorhexis-IOL overlap contributed to greater IOL misalignment in pediatric cataract patients with primary in-the-bag IOL implantation,which may compromise postoperative optical quality by increasing internal tHOA and astigmatism.展开更多
Background:To investigate the decentration and tilt of plate-haptic multifocal intraocular lenses(MfIOLs)in myopic eyes.Methods:Myopic(axial length[AXL]>24.5 mm)and non-myopic(21.0 mm<AXL≤24.5 mm)cataract eyes ...Background:To investigate the decentration and tilt of plate-haptic multifocal intraocular lenses(MfIOLs)in myopic eyes.Methods:Myopic(axial length[AXL]>24.5 mm)and non-myopic(21.0 mm<AXL≤24.5 mm)cataract eyes were enrolled in this prospective study and randomly assigned to receive implantation of Zeiss AT LISA tri 839MP lenses(Group A)or Tecnis ZMB00 lenses(Group B).In total,122 eyes of 122 patients were available for analysis.Decentration and tilt of MfIOLs,high-order aberrations(HOAs),and modulation transfer functions(MTFs)were evaluated using the OPD-Scan III aberrometer 3 months postoperatively.Subjective symptoms were assessed with a Quality of Vision questionnaire.Results:Near and distance visual acuities,tilt and horizontal decentration did not differ between the two groups,postoperatively.However,myopic eyes of Group B showed greater vertical decentration than those of Group A(−0.17±0.14 mm vs.-0.03±0.09 mm,respectively),particularly when the MfIOLs were placed horizontally or obliquely.Overall decentration of myopic eyes was greater in Group B than in Group A(0.41±0.15 mm vs.0.16±0.10 mm,respectively).In Group B,AXL was negatively correlated with vertical decentration and positively correlated with overall decentration.No such correlations were found in Group A.Intraocular total HOAs,coma,trefoil and spherical aberrations were lower in Group A than in Group B for a 6.0 mm pupil among myopic eyes.Generally,Group A had better MTFs and fewer subjective symptoms than Group B among myopic eyes.Conclusions:Plate-haptic design of MfIOLs may be a suggested option for myopic cataract eyes due to the less inferior decentration and better visual quality postoperatively.展开更多
Background:This retrospective study was designed to investigate the sole influence of orthokeratology(OK)lens fitting decentration on the Zernike coefficients of the reshaped anterior corneal surface.Methods:This stud...Background:This retrospective study was designed to investigate the sole influence of orthokeratology(OK)lens fitting decentration on the Zernike coefficients of the reshaped anterior corneal surface.Methods:This study comprised a review of 106 right eyes and measurements of corneal topography both before OK and at 1-month follow-up visit.A routine was designed to calculate local corneal surface astigmatism and assist the determination of OK lens fitting decentration from pupil center.The pupil-centered corneal Zernike coefficients of baseline(PCCB)and post-treatment(PCCP)were calculated.Meanwhile,the OK-lens-centered corneal Zernike coefficients of post-treatment(OCCP)were also calculated and considered as the presumptive ideal fitting group without decentration.Relationships between lens fitting decentration and the change of Zernike coefficients including(PCCP−PCCB)and(PCCP−OCCP)were analyzed.Results:Patients with a mean age of 11±2.36 years old had an average spherical equivalent refractive error of−3.52±1.06 D before OK.One month after treatment,OK lens fitting decentration from pupil center was 0.68±0.35 mm.RMS of 3rd-order(P<0.05),RMS of 4th-order(P<0.001)and RMS of total high order(P<0.001)corneal Zernike coefficients were increased in PCCP by comparing with OCCP,which was solely caused by lens fitting decentration.Nevertheless,no significant difference was observed in C^(0)_(2)(P>0.05).For the high order corneal Zernike coefficients in(PCCP–OCCP),radial distance of decentration was correlated with C^(−1)_(3)(r=−0.296,P<0.05),C^(1)_(3)(r=−0.396,P<0.001),and C^(0)_(4)(r=0.449,P<0.001),horizontal decentration was significantly correlated with C^(1)_(3)(r=0.901,P<0.001)and C^(1)_(5)(r=0.340,P<0.001),and vertical decentration was significantly correlated with C^(−1)_(3)(r=0.904,P<0.001).Conclusions:OK lens fitting decentration within 1.5 mm hardly influenced the change of corneal spherical power for myopia correction,but significantly induced additional corneal high order Zernike coefficients including C^(−1)_(3),C^(1)_(3),C^(0)_(4),and C^(1)_(5).展开更多
Optimizing routing and resource allocation in decentralized unmanned aerial vehicle(UAV)networks remains challenging due to interference and rapidly changing topologies.The authors introduce a novel framework combinin...Optimizing routing and resource allocation in decentralized unmanned aerial vehicle(UAV)networks remains challenging due to interference and rapidly changing topologies.The authors introduce a novel framework combining double deep Q-networks(DDQNs)and graph neural networks(GNNs)for joint routing and resource allocation.The framework uses GNNs to model the network topology and DDQNs to adaptively control routing and resource allocation,addressing interference and improving network performance.Simulation results show that the proposed approach outperforms traditional methods such as Closest-to-Destination(c2Dst),Max-SINR(mSINR),and Multi-Layer Perceptron(MLP)-based models,achieving approximately 23.5% improvement in throughput,50% increase in connection probability,and 17.6% reduction in number of hops,demonstrating its effectiveness in dynamic UAV networks.展开更多
This work evaluates an architecture for decentralized authentication of Internet of Things(IoT)devices in Low Earth Orbit(LEO)satellite networks using IOTA Identity technology.To the best of our knowledge,it is the fi...This work evaluates an architecture for decentralized authentication of Internet of Things(IoT)devices in Low Earth Orbit(LEO)satellite networks using IOTA Identity technology.To the best of our knowledge,it is the first proposal to integrate IOTA’s Directed Acyclic Graph(DAG)-based identity framework into satellite IoT environments,enabling lightweight and distributed authentication under intermittent connectivity.The system leverages Decentralized Identifiers(DIDs)and Verifiable Credentials(VCs)over the Tangle,eliminating the need for mining and sequential blocks.An identity management workflow is implemented that supports the creation,validation,deactivation,and reactivation of IoT devices,and is experimentally validated on the Shimmer Testnet.Three metrics are defined and measured:resolution time,deactivation time,and reactivation time.To improve robustness,an algorithmic optimization is introduced that minimizes communication overhead and reduces latency during deactivation.The experimental results are compared with orbital simulations of satellite revisit times to assess operational feasibility.Unlike blockchain-based approaches,which typically suffer from high confirmation delays and scalability constraints,the proposed DAG architecture provides fast,cost-free operations suitable for resource-constrained IoT devices.The results show that authentication can be efficiently performed within satellite connectivity windows,positioning IOTA Identity as a viable solution for secure and scalable IoT authentication in LEO satellite networks.展开更多
The relation between conflict and governance has been dominated by type of government rather than by system of government.With increasing conflict in countries with ethnic and religious diversity,the debate has gradua...The relation between conflict and governance has been dominated by type of government rather than by system of government.With increasing conflict in countries with ethnic and religious diversity,the debate has gradually shifted to understand better the link between conflict and system of government.There is a growing evidence that suggests federal system performs better than unitary system in managing diversity and reducing conflict.Decentralization is even seen to be more effective than federal system not only in managing diversity and reducing conflict but also in delivering public goods.This article provides an account of evolution of system of government in South Sudan.It finds a clear association of centralized unitary system with violent conflict and a relative peace during period of decentralized government or federal system.A decentralized federal system may be appropriate for South Sudan in managing diversity and mitigating conflict.Despite the popular demand by their citizens for a federal system to manage diversity and reduce violent conflict,the ruling elites in the post-independent South Sudan adopted instead an autocratic centralized unitary system that contributed among other factors to the persistent violent conflicts,erosion of social cohesion,and rising mistrust between state and citizens and between and among the communities of South Sudan.展开更多
As AI systems scale, the limitations of cloud-based architectures, including latency, bandwidth, and privacy concerns, demand decentralized alternatives. Federated learning (FL) and Edge AI provide a paradigm shift by...As AI systems scale, the limitations of cloud-based architectures, including latency, bandwidth, and privacy concerns, demand decentralized alternatives. Federated learning (FL) and Edge AI provide a paradigm shift by combining privacy preserving training with efficient, on device computation. This paper introduces a cutting-edge FL-edge integration framework, achieving a 10% to 15% increase in model accuracy and reducing communication costs by 25% in heterogeneous environments. Blockchain based secure aggregation ensures robust and tamper-proof model updates, while exploratory quantum AI techniques enhance computational efficiency. By addressing key challenges such as device variability and non-IID data, this work sets the stage for the next generation of adaptive, privacy-first AI systems, with applications in IoT, healthcare, and autonomous systems.展开更多
Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with H_(2) production can reduce the carbon footprint associated with transportation of water,waste,and energy carrier.This study...Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with H_(2) production can reduce the carbon footprint associated with transportation of water,waste,and energy carrier.This study reports Ir-doped NiFe_(2)O_(4)(NFI,~5 at%Ir)spinel layer with TiO_(2) overlayer(NFI/TiO_(2)),as a scalable heterojunction anode for direct electrolysis of wastewater with circumneutral pH in a single-compartment cell.In dilute(0.1 M)NaCl solutions,the NFI/TiO_(2) marks superior activity and selectivity for chlorine evolution reaction,outperforming the benchmark IrO_(2).Robust operation in near-neutral pH was confirmed.Electroanalyses including operando X-ray absorption spectroscopy unveiled crucial roles of TiO_(2) which serves both as the primary site for Cl−chemisorption and a protective layer for NFI as an ohmic contact.Galvanostatic electrolysis of NH4+-laden synthetic wastewater demonstrated that NFI/TiO_(2)not only achieves quasi-stoichiometric NH_(4)^(+)-to-N_(2)conversion,but also enhances H_(2)generation efficiency with minimal competing reactions such as reduction of dissolved oxygen and reactive chlorine.The scaled-up WEC with NFI/TiO_(2)was demonstrated for electrolysis of toilet wastewater.展开更多
In response to the critical need to balance fiscal expenditure governance with sustainable development,this study identifies the optimal level of fiscal expenditure decentralization that enhances sustainable outcomes....In response to the critical need to balance fiscal expenditure governance with sustainable development,this study identifies the optimal level of fiscal expenditure decentralization that enhances sustainable outcomes.The study aims to determine the optimal expenditure decentralization that maximizes sustainable development outcomes across these dimensions.Theoretically,we analyze the impact mechanism of expenditure decentralization on sustainable development and hypothesize that there is an inverted U-shaped relationship between them,along with the possibility of finding an optimal level of expenditure decentralization.We test this hypothesis by measuring sustainable development in the context of a panel data set for 52 countries covering the period 1991–2016 using the National Sustainable Development Index(NSDI).We find strong support for the inverted U-shaped relationship between expenditure decentralization and sustainable development in both the short and long run.Sustainable development is the coordination of economic,social,and environmental development to balance intergenerational welfare and maximize the total welfare of all generations.Excessive and insufficient expenditure decentralization can potentially negatively affect the efficiency of public goods provision and residents’utility,thereby adversely impacting total welfare and sustainable development.The results are robust to alternative specifications and to IV estimation to correct for potential endogeneity.The expenditure decentralization level most conducive to sustainable development lies between 30.9%and 34.5%.The optimal decentralization range was determined using the Lind–Mehlum method,supporting the main findings of this study.This research thus contributes to the literature by quantifying the complex relationship between fiscal decentralization policies and sustainable development,providing a clear,actionable pathway for policymakers seeking sustainable outcomes.展开更多
This paper introduces federated services as a smart service ecology with federated security to align distributed data supply with diversified service demands spanning digital and societal contexts.It presents the comp...This paper introduces federated services as a smart service ecology with federated security to align distributed data supply with diversified service demands spanning digital and societal contexts.It presents the comprehensive researches on the theoretical foundation and technical system of federated services,aiming at advancing our understanding and implementation of this novel service paradigm.First,a thorough examination of the characteristics of federated security within federated services is conducted.Then,a five-layer technical framework is formulated under a decentralized intelligent architecture,ensuring secure,agile,and adaptable service provision.On this basis,the operational mechanisms underlying data federation and service confederation is analyzed,with emphasis on the smart supply-demand matching model.Furthermore,a scenario-oriented taxonomy of federated services accompanied by illustrative examples is proposed.Our work offers actionable insights and roadmap for realizing and advancing federated services,contributing to the refinement and wider adoption of this transformative service paradigm in the digital era.展开更多
The rapid evolution of quantum computing poses significant threats to traditional cryptographic schemes,particularly in Decentralized Finance(DeFi)systems that rely on legacy mechanisms like RSA and ECDSA for digital ...The rapid evolution of quantum computing poses significant threats to traditional cryptographic schemes,particularly in Decentralized Finance(DeFi)systems that rely on legacy mechanisms like RSA and ECDSA for digital identity verification.This paper proposes a quantum-resilient,blockchain-based identity verification framework designed to address critical challenges in privacy preservation,scalability,and post-quantum security.The proposed model integrates Post-quantum Cryptography(PQC),specifically lattice-based cryptographic primitives,with Decentralized Identifiers(DIDs)and Zero-knowledge Proofs(ZKPs)to ensure verifiability,anonymity,and resistance to quantum attacks.A dual-layer architecture is introduced,comprising an identity layer for credential generation and validation,and an application layer for DeFi protocol integration.To evaluate its performance,the framework is tested on multiple real-world DeFi platforms using metrics such as verification latency,throughput,attack resistance,energy efficiency,and quantum attack simulation.The results demonstrate that the proposed framework achieves 90%latency reduction and over 35%throughput improvement compared to traditional blockchain identity solutions.It also exhibits a high quantum resistance score(95/100),with successful secure verification under simulated quantum adversaries.The revocation mechanism—implemented using Merkle-tree-based proofs—achieves average response times under 40 ms,and the system maintains secure operations with energy consumption below 9 J per authentication cycle.Additionally,the paper presents a security and cost tradeoff analysis using ZKP schemes such as Bulletproofs and STARKs,revealing superior bits-per-byte efficiency and reduced proof sizes.Real-world adoption scenarios,including integration with six major DeFi protocols,indicate a 25%increase in verified users and a 15%improvement in Total Value Locked(TVL).The proposed solution is projected to remain secure until 2041(basic version)and 2043(advanced version),ensuring long-term sustainability and future-proofing against evolving quantum threats.This work establishes a scalable,privacy-preserving identity model that aligns with emerging post-quantum security standards for decentralized ecosystems.展开更多
Blockchain Technology(BT)has emerged as a transformative solution for improving the efficacy,security,and transparency of supply chain intelligence.Traditional Supply Chain Management(SCM)systems frequently have probl...Blockchain Technology(BT)has emerged as a transformative solution for improving the efficacy,security,and transparency of supply chain intelligence.Traditional Supply Chain Management(SCM)systems frequently have problems such as data silos,a lack of visibility in real time,fraudulent activities,and inefficiencies in tracking and traceability.Blockchain’s decentralized and irreversible ledger offers a solid foundation for dealing with these issues;it facilitates trust,security,and the sharing of data in real-time among all parties involved.Through an examination of critical technologies,methodology,and applications,this paper delves deeply into computer modeling based-blockchain framework within supply chain intelligence.The effect of BT on SCM is evaluated by reviewing current research and practical applications in the field.As part of the process,we delved through the research on blockchain-based supply chain models,smart contracts,Decentralized Applications(DApps),and how they connect to other cutting-edge innovations like Artificial Intelligence(AI)and the Internet of Things(IoT).To quantify blockchain’s performance,the study introduces analytical models for efficiency improvement,security enhancement,and scalability,enabling computational assessment and simulation of supply chain scenarios.These models provide a structured approach to predicting system performance under varying parameters.According to the results,BT increases efficiency by automating transactions using smart contracts,increases security by using cryptographic techniques,and improves transparency in the supply chain by providing immutable records.Regulatory concerns,challenges with interoperability,and scalability all work against broad adoption.To fully automate and intelligently integrate blockchain with AI and the IoT,additional research is needed to address blockchain’s current limitations and realize its potential for supply chain intelligence.展开更多
In this work, we address the codiagnosability analysis problem of a networked discrete event system under malicious attacks. The considered system is modeled by a labeled Petri net and is monitored by a series of site...In this work, we address the codiagnosability analysis problem of a networked discrete event system under malicious attacks. The considered system is modeled by a labeled Petri net and is monitored by a series of sites, in which each site possesses its own set of sensors, without requiring communication among sites or to any coordinators. A net is said to be codiagnosable with respect to a fault if at least one site could deduce the occurrence of this fault within finite steps. In this context, we focus on a type of malicious attack that is called stealthy intermittent replacement attack. The stealthiness demands that the corrupted observations should be consistent with the system's normal behavior, while the intermittent replacement setting entails that the replaced transition labels must be recovered within a bounded of consecutive corrupted observations(called as K-corruption intermittent attack). Particularly, there exists a coordination between attackers that are separately effected on different sites, which holds the same corrupted observation for each common transition under attacks. From an attacker viewpoint, this work aims to design Kcorruption intermittent attacks for violating the codiagnosability of systems. For this purpose, we propose an attack automaton to analyze K-corruption intermittent attack for each site, and build a new structure called complete attack graph that is used to analyze all the potential attacked paths. Finally, an algorithm is inferred to obtain the K-corruption intermittent attacks, and examples are given to show the proposed attack strategy.展开更多
Smart contracts on the Ethereum blockchain continue to revolutionize decentralized applications (dApps) by allowing for self-executing agreements. However, bad actors have continuously found ways to exploit smart cont...Smart contracts on the Ethereum blockchain continue to revolutionize decentralized applications (dApps) by allowing for self-executing agreements. However, bad actors have continuously found ways to exploit smart contracts for personal financial gain, which undermines the integrity of the Ethereum blockchain. This paper proposes a computer program called SADA (Static and Dynamic Analyzer), a novel approach to smart contract vulnerability detection using multiple Large Language Model (LLM) agents to analyze and flag suspicious Solidity code for Ethereum smart contracts. SADA not only improves upon existing vulnerability detection methods but also paves the way for more secure smart contract development practices in the rapidly evolving blockchain ecosystem.展开更多
Traditional Internet of Things(IoT)architectures that rely on centralized servers for data management and decision-making are vulnerable to security threats and privacy leakage.To address this issue,blockchain has bee...Traditional Internet of Things(IoT)architectures that rely on centralized servers for data management and decision-making are vulnerable to security threats and privacy leakage.To address this issue,blockchain has been advocated for decentralized data management in a tamper-resistance,traceable,and transparent manner.However,a major issue that hinders the integration of blockchain and IoT lies in that,it is rather challenging for resource-constrained IoT devices to perform computation-intensive blockchain consensuses such as Proof-of-Work(PoW).Furthermore,the incentive mechanism of PoW pushes lightweight IoT nodes to aggregate their computing power to increase the possibility of successful block generation.Nevertheless,this eventually leads to the formation of computing power alliances,and significantly compromises the decentralization and security of BlockChain-aided IoT(BC-IoT)networks.To cope with these issues,we propose a lightweight consensus protocol for BC-IoT,called Proof-of-Trusted-Work(PoTW).The goal of the proposed consensus is to disincentivize the centralization of computing power and encourage the independent participation of lightweight IoT nodes in blockchain consensus.First,we put forth an on-chain reputation evaluation rule and a reputation chain for PoTW to enable the verifiability and traceability of nodes’reputations based on their contributions of computing power to the blockchain consensus,and we incorporate the multi-level block generation difficulty as a rewards for nodes to accumulate reputations.Second,we model the block generation process of PoTW and analyze the block throughput using the continuous time Markov chain.Additionally,we define and optimize the relative throughput gain to quantify and maximize the capability of PoTW that suppresses the computing power centralization(i.e.,centralization suppression).Furthermore,we investigate the impact of the computing power of the computing power alliance and the levels of block generation difficulty on the centralization suppression capability of PoTW.Finally,simulation results demonstrate the consistency of the analytical results in terms of block throughput.In particular,the results show that PoTW effectively reduces the block generation proportion of the computing power alliance compared with PoW,while simultaneously improving that of individual lightweight nodes.This indicates that PoTW is capable of suppressing the centralization of computing power to a certain degree.Moreover,as the levels of block generation difficulty in PoTW increase,its centralization suppression capability strengthens.展开更多
The proof-of-stake(PoS)mechanism is a consensus protocol within blockchain technology that determines the validation of transactions and the minting of new blocks based on the participant’s stake in the cryptocurrenc...The proof-of-stake(PoS)mechanism is a consensus protocol within blockchain technology that determines the validation of transactions and the minting of new blocks based on the participant’s stake in the cryptocurrency network.In contrast to proof-of-work(PoW),which relies on computational power to validate transactions,PoS employs a deterministic and resourceefficient approach to elect validators.Whereas,an inherent risk of PoS is the potential for centralization among a small cohort of network participants possessing substantial stakes,jeopardizing system decentralization and posing security threats.To mitigate centralization issues within PoS,this study introduces an incentive-aligned mechanism named decentralized proof-of-stake(DePoS),wherein the second-largest stakeholder is chosen as the final validator with a higher probability.Integrated with the verifiable random function(VRF),DePoS rewards the largest stakeholder with uncertainty,thus disincentivizing stakeholders from accumulating the largest stake.Additionally,a dynamic evolutionary game model is innovatively developed to simulate the evolution of staking pools,thus facilitating the investigation of staking pool selection dynamics and equilibrium stability across PoS and DePoS systems.The findings demonstrate that DePoS generally fosters wealth decentralization by discouraging the accumulation of significant cryptocurrency holdings.Through theoretical analysis of stakeholder predilection in staking pool selection and the simulation of the evolutionary tendency in pool scale,this research demonstrates the comparative advantage in decentralization offered by DePoS over the conventional PoS.展开更多
With the evolution of next-generation communication networks,ensuring robust Core Network(CN)architecture and data security has become paramount.This paper addresses critical vulnerabilities in the architecture of CN ...With the evolution of next-generation communication networks,ensuring robust Core Network(CN)architecture and data security has become paramount.This paper addresses critical vulnerabilities in the architecture of CN and data security by proposing a novel framework based on blockchain technology that is specifically designed for communication networks.Traditional centralized network architectures are vulnerable to Distributed Denial of Service(DDoS)attacks,particularly in roaming scenarios where there is also a risk of private data leakage,which imposes significant operational demands.To address these issues,we introduce the Blockchain-Enhanced Core Network Architecture(BECNA)and the Secure Decentralized Identity Authentication Scheme(SDIDAS).The BECNA utilizes blockchain technology to decentralize data storage,enhancing network security,stability,and reliability by mitigating Single Points of Failure(SPoF).The SDIDAS utilizes Decentralized Identity(DID)technology to secure user identity data and streamline authentication in roaming scenarios,significantly reducing the risk of data breaches during cross-network transmissions.Our framework employs Ethereum,free5GC,Wireshark,and UERANSIM tools to create a robust,tamper-evident system model.A comprehensive security analysis confirms substantial improvements in user privacy and network security.Simulation results indicate that our approach enhances communication CNs security and reliability,while also ensuring data security.展开更多
基金Supported by Haidian District Innovation and Transformation Fund of China,No. HDCXZHK2021212
文摘We find that tilt and decentration of intraocular lens (IOL) commonly cause visualquality deterioration after cataract surgery. Multiple factors affect IOL tilt anddecentration in the pre-, mid-, and post-operation phases. Moreover, the tilt anddecentration of 1-piece IOL are less correlated with internal ocular HOAs thanthose of 3-piece IOL. Aspherical IOLs are more sensitive to decentration or tiltthan spherical IOLs. Furthermore, the optical performance of toric IOLs with anaccurate axis remains stable irrespective of tilt and decentration. The opticalquality of asymmetric multifocal IOLs varies significantly after decentration andtilt in different directions. The image quality enhances or deteriorates in thedirection of the decentered IOL. An extended depth of focus IOL can achievegood visual acuity in the distant, intermediate, and near range. Additionally, itstilt and decentration have less impact on the vision than bifocal and trifocal IOL.This is the first review that compares the effect of IOL tilt and decentration onimage quality for various IOL designs. The result indicates that a deeperunderstanding of tilt and decentration of various IOLs can help achieve a bettervisual effect to visually improve refractive cataract surgery.
基金Sponsored by the Eleventh Five-year Plan Defense Pre-research Fund ( Grant No 51309040201)
文摘As the geometric center of circular grating does not coincide with the rotation center,the angle measurement error of circular grating is analyzed. Based on the moire fringe equations in decentration condition,the mathematical model of angle measurement error is derived. It is concluded that the decentration between the centre of circular grating and the center of revolving shaft leads to the first-harmonic error of angle measurement. The correctness of the result is proved by experimental data. The method of error compensation is presented,and the angle measurement accuracy of the circular grating is effectively improved by the error compensation.
文摘· AIM: To evaluate the optical performance of toric intraocular lenses(IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned.· METHODS: Optical performances of toric T5 and SN60 AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from0° to 90°. The ratio of the modulation transfer function(MTF) between a decentered and a centered IOL(MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance.· RESULTS: Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased,whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentrationratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60 AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60 AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs.· CONCLUSION: Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.
基金supported by the Wenzhou Basic Research Foundation(20240348)the National Natural Science Foundation of China(82371042),and the Provincial Construction Project of Zhejiang(WKJ-ZJ-2441).
文摘To investigate the characteristics and associated factors of intraocular lens(IOL)tilt and decentration in pediatric cataract patients undergoing primary IOL implantation and to explore their impact on postoperative optical quality.Methods Children who underwent cataract extraction with posterior capsulotomy,primary anterior vitrectomy,and in-the-bag IOL implantation over 6 months were enrolled.Patient data and ocular biometric parameters were retrieved from electronic files.Retroillumination images were obtained to evaluate capsular outcomes.IOL tilt and decentration were assessed using the swept-source optical coherence tomography,and wavefront aberrations were measured with the OPD-Scan III.Results A total of 125 eyes from 125 patients with a mean age at surgery of 4.74±1.49 years were included.The IOLs demonstrated a mean tilt of 6.02±1.97°toward the temporal direction and a mean decentration of 0.28±0.13〓〓mm toward the superior-temporal direction.Multivariate analysis revealed that shorter axial length(AL;P=0.009)and significant cortical proliferation(P〓〓=〓〓0.021)were associated with greater IOL tilt.In addition,smaller corneal diameter(CD;P=0.008)and incomplete capsulorhexis-IOL overlap(P=0.022)were associated with larger IOL decentration.Patients with IOL tilt≥7°and decentration≥0.40〓〓mm exhibited higher internal total higher-order aberrations(tHOA)and internal astigmatism,both of which were positively correlated with IOL misalignment(all P〓〓<〓〓0.05)Conclusions Shorter AL,smaller CD,significant cortical proliferation,and incomplete capsulorhexis-IOL overlap contributed to greater IOL misalignment in pediatric cataract patients with primary in-the-bag IOL implantation,which may compromise postoperative optical quality by increasing internal tHOA and astigmatism.
基金Publication of this article was supported by research grants from the National Natural Science Foundation of the People’s Republic of China(grant nos.81870642,81670835 and 81470613)the Shanghai High Myopia Study Group,the International Science and Technology Cooperation Foundation of Shanghai(grant no.14430721100)the Outstanding Youth Medical Talents Program of Shanghai Health and Family Planning Commission(grant no.2017YQ011).
文摘Background:To investigate the decentration and tilt of plate-haptic multifocal intraocular lenses(MfIOLs)in myopic eyes.Methods:Myopic(axial length[AXL]>24.5 mm)and non-myopic(21.0 mm<AXL≤24.5 mm)cataract eyes were enrolled in this prospective study and randomly assigned to receive implantation of Zeiss AT LISA tri 839MP lenses(Group A)or Tecnis ZMB00 lenses(Group B).In total,122 eyes of 122 patients were available for analysis.Decentration and tilt of MfIOLs,high-order aberrations(HOAs),and modulation transfer functions(MTFs)were evaluated using the OPD-Scan III aberrometer 3 months postoperatively.Subjective symptoms were assessed with a Quality of Vision questionnaire.Results:Near and distance visual acuities,tilt and horizontal decentration did not differ between the two groups,postoperatively.However,myopic eyes of Group B showed greater vertical decentration than those of Group A(−0.17±0.14 mm vs.-0.03±0.09 mm,respectively),particularly when the MfIOLs were placed horizontally or obliquely.Overall decentration of myopic eyes was greater in Group B than in Group A(0.41±0.15 mm vs.0.16±0.10 mm,respectively).In Group B,AXL was negatively correlated with vertical decentration and positively correlated with overall decentration.No such correlations were found in Group A.Intraocular total HOAs,coma,trefoil and spherical aberrations were lower in Group A than in Group B for a 6.0 mm pupil among myopic eyes.Generally,Group A had better MTFs and fewer subjective symptoms than Group B among myopic eyes.Conclusions:Plate-haptic design of MfIOLs may be a suggested option for myopic cataract eyes due to the less inferior decentration and better visual quality postoperatively.
基金supported by the Scientific and Technological Program of Wenzhou[Y20160438,G20160033]National Natural Science Foundation of China[61775171]+1 种基金Natural Science Foundation of Zhejiang Province[LY14F050009,LY16H120007]National Key Research and Development Program of China[2016YFC0100200].
文摘Background:This retrospective study was designed to investigate the sole influence of orthokeratology(OK)lens fitting decentration on the Zernike coefficients of the reshaped anterior corneal surface.Methods:This study comprised a review of 106 right eyes and measurements of corneal topography both before OK and at 1-month follow-up visit.A routine was designed to calculate local corneal surface astigmatism and assist the determination of OK lens fitting decentration from pupil center.The pupil-centered corneal Zernike coefficients of baseline(PCCB)and post-treatment(PCCP)were calculated.Meanwhile,the OK-lens-centered corneal Zernike coefficients of post-treatment(OCCP)were also calculated and considered as the presumptive ideal fitting group without decentration.Relationships between lens fitting decentration and the change of Zernike coefficients including(PCCP−PCCB)and(PCCP−OCCP)were analyzed.Results:Patients with a mean age of 11±2.36 years old had an average spherical equivalent refractive error of−3.52±1.06 D before OK.One month after treatment,OK lens fitting decentration from pupil center was 0.68±0.35 mm.RMS of 3rd-order(P<0.05),RMS of 4th-order(P<0.001)and RMS of total high order(P<0.001)corneal Zernike coefficients were increased in PCCP by comparing with OCCP,which was solely caused by lens fitting decentration.Nevertheless,no significant difference was observed in C^(0)_(2)(P>0.05).For the high order corneal Zernike coefficients in(PCCP–OCCP),radial distance of decentration was correlated with C^(−1)_(3)(r=−0.296,P<0.05),C^(1)_(3)(r=−0.396,P<0.001),and C^(0)_(4)(r=0.449,P<0.001),horizontal decentration was significantly correlated with C^(1)_(3)(r=0.901,P<0.001)and C^(1)_(5)(r=0.340,P<0.001),and vertical decentration was significantly correlated with C^(−1)_(3)(r=0.904,P<0.001).Conclusions:OK lens fitting decentration within 1.5 mm hardly influenced the change of corneal spherical power for myopia correction,but significantly induced additional corneal high order Zernike coefficients including C^(−1)_(3),C^(1)_(3),C^(0)_(4),and C^(1)_(5).
文摘Optimizing routing and resource allocation in decentralized unmanned aerial vehicle(UAV)networks remains challenging due to interference and rapidly changing topologies.The authors introduce a novel framework combining double deep Q-networks(DDQNs)and graph neural networks(GNNs)for joint routing and resource allocation.The framework uses GNNs to model the network topology and DDQNs to adaptively control routing and resource allocation,addressing interference and improving network performance.Simulation results show that the proposed approach outperforms traditional methods such as Closest-to-Destination(c2Dst),Max-SINR(mSINR),and Multi-Layer Perceptron(MLP)-based models,achieving approximately 23.5% improvement in throughput,50% increase in connection probability,and 17.6% reduction in number of hops,demonstrating its effectiveness in dynamic UAV networks.
基金This work is part of the‘Intelligent and Cyber-Secure Platform for Adaptive Optimization in the Simultaneous Operation of Heterogeneous Autonomous Robots(PICRAH4.0)’with reference MIG-20232082,funded by MCIN/AEI/10.13039/501100011033supported by the Universidad Internacional de La Rioja(UNIR)through the Precompetitive Research Project entitled“Nuevos Horizontes en Internet de las Cosas y NewSpace(NEWIOT)”,reference PP-2024-13,funded under the 2024 Call for Research Projects.
文摘This work evaluates an architecture for decentralized authentication of Internet of Things(IoT)devices in Low Earth Orbit(LEO)satellite networks using IOTA Identity technology.To the best of our knowledge,it is the first proposal to integrate IOTA’s Directed Acyclic Graph(DAG)-based identity framework into satellite IoT environments,enabling lightweight and distributed authentication under intermittent connectivity.The system leverages Decentralized Identifiers(DIDs)and Verifiable Credentials(VCs)over the Tangle,eliminating the need for mining and sequential blocks.An identity management workflow is implemented that supports the creation,validation,deactivation,and reactivation of IoT devices,and is experimentally validated on the Shimmer Testnet.Three metrics are defined and measured:resolution time,deactivation time,and reactivation time.To improve robustness,an algorithmic optimization is introduced that minimizes communication overhead and reduces latency during deactivation.The experimental results are compared with orbital simulations of satellite revisit times to assess operational feasibility.Unlike blockchain-based approaches,which typically suffer from high confirmation delays and scalability constraints,the proposed DAG architecture provides fast,cost-free operations suitable for resource-constrained IoT devices.The results show that authentication can be efficiently performed within satellite connectivity windows,positioning IOTA Identity as a viable solution for secure and scalable IoT authentication in LEO satellite networks.
文摘The relation between conflict and governance has been dominated by type of government rather than by system of government.With increasing conflict in countries with ethnic and religious diversity,the debate has gradually shifted to understand better the link between conflict and system of government.There is a growing evidence that suggests federal system performs better than unitary system in managing diversity and reducing conflict.Decentralization is even seen to be more effective than federal system not only in managing diversity and reducing conflict but also in delivering public goods.This article provides an account of evolution of system of government in South Sudan.It finds a clear association of centralized unitary system with violent conflict and a relative peace during period of decentralized government or federal system.A decentralized federal system may be appropriate for South Sudan in managing diversity and mitigating conflict.Despite the popular demand by their citizens for a federal system to manage diversity and reduce violent conflict,the ruling elites in the post-independent South Sudan adopted instead an autocratic centralized unitary system that contributed among other factors to the persistent violent conflicts,erosion of social cohesion,and rising mistrust between state and citizens and between and among the communities of South Sudan.
文摘As AI systems scale, the limitations of cloud-based architectures, including latency, bandwidth, and privacy concerns, demand decentralized alternatives. Federated learning (FL) and Edge AI provide a paradigm shift by combining privacy preserving training with efficient, on device computation. This paper introduces a cutting-edge FL-edge integration framework, achieving a 10% to 15% increase in model accuracy and reducing communication costs by 25% in heterogeneous environments. Blockchain based secure aggregation ensures robust and tamper-proof model updates, while exploratory quantum AI techniques enhance computational efficiency. By addressing key challenges such as device variability and non-IID data, this work sets the stage for the next generation of adaptive, privacy-first AI systems, with applications in IoT, healthcare, and autonomous systems.
基金supported by the National Research Foundation of Korea(NRF)grants(2022R1A2C4001228,2022M3H4A4097524,2022M3I3A1082499,and 2021M3I3A1084818)the Technology Innovation Program(20026415)of the Ministry of Trade,Industry&Energy(MOTIE,Korea)the supports from Nanopac for fabrication of scaled-up reactor.
文摘Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with H_(2) production can reduce the carbon footprint associated with transportation of water,waste,and energy carrier.This study reports Ir-doped NiFe_(2)O_(4)(NFI,~5 at%Ir)spinel layer with TiO_(2) overlayer(NFI/TiO_(2)),as a scalable heterojunction anode for direct electrolysis of wastewater with circumneutral pH in a single-compartment cell.In dilute(0.1 M)NaCl solutions,the NFI/TiO_(2) marks superior activity and selectivity for chlorine evolution reaction,outperforming the benchmark IrO_(2).Robust operation in near-neutral pH was confirmed.Electroanalyses including operando X-ray absorption spectroscopy unveiled crucial roles of TiO_(2) which serves both as the primary site for Cl−chemisorption and a protective layer for NFI as an ohmic contact.Galvanostatic electrolysis of NH4+-laden synthetic wastewater demonstrated that NFI/TiO_(2)not only achieves quasi-stoichiometric NH_(4)^(+)-to-N_(2)conversion,but also enhances H_(2)generation efficiency with minimal competing reactions such as reduction of dissolved oxygen and reactive chlorine.The scaled-up WEC with NFI/TiO_(2)was demonstrated for electrolysis of toilet wastewater.
基金supported by Zhejiang Province Philosophy and Social Science Planning Fund(24NDQN090YB)Hangzhou City Philosophy and Social Science Planning Fund(Z23JC041)the Major program project of the National Social Science Fund of China(No:19ZDA055).
文摘In response to the critical need to balance fiscal expenditure governance with sustainable development,this study identifies the optimal level of fiscal expenditure decentralization that enhances sustainable outcomes.The study aims to determine the optimal expenditure decentralization that maximizes sustainable development outcomes across these dimensions.Theoretically,we analyze the impact mechanism of expenditure decentralization on sustainable development and hypothesize that there is an inverted U-shaped relationship between them,along with the possibility of finding an optimal level of expenditure decentralization.We test this hypothesis by measuring sustainable development in the context of a panel data set for 52 countries covering the period 1991–2016 using the National Sustainable Development Index(NSDI).We find strong support for the inverted U-shaped relationship between expenditure decentralization and sustainable development in both the short and long run.Sustainable development is the coordination of economic,social,and environmental development to balance intergenerational welfare and maximize the total welfare of all generations.Excessive and insufficient expenditure decentralization can potentially negatively affect the efficiency of public goods provision and residents’utility,thereby adversely impacting total welfare and sustainable development.The results are robust to alternative specifications and to IV estimation to correct for potential endogeneity.The expenditure decentralization level most conducive to sustainable development lies between 30.9%and 34.5%.The optimal decentralization range was determined using the Lind–Mehlum method,supporting the main findings of this study.This research thus contributes to the literature by quantifying the complex relationship between fiscal decentralization policies and sustainable development,providing a clear,actionable pathway for policymakers seeking sustainable outcomes.
基金supported by the National Key Research and Development Program of China(2021YFB2104800)the National Natural Science Foundation of China(62103411,62436010,72171230)the Science and Technology Development Fund of Macao SAR(0093/2023/RIA2,0050/2020/A1).
文摘This paper introduces federated services as a smart service ecology with federated security to align distributed data supply with diversified service demands spanning digital and societal contexts.It presents the comprehensive researches on the theoretical foundation and technical system of federated services,aiming at advancing our understanding and implementation of this novel service paradigm.First,a thorough examination of the characteristics of federated security within federated services is conducted.Then,a five-layer technical framework is formulated under a decentralized intelligent architecture,ensuring secure,agile,and adaptable service provision.On this basis,the operational mechanisms underlying data federation and service confederation is analyzed,with emphasis on the smart supply-demand matching model.Furthermore,a scenario-oriented taxonomy of federated services accompanied by illustrative examples is proposed.Our work offers actionable insights and roadmap for realizing and advancing federated services,contributing to the refinement and wider adoption of this transformative service paradigm in the digital era.
文摘The rapid evolution of quantum computing poses significant threats to traditional cryptographic schemes,particularly in Decentralized Finance(DeFi)systems that rely on legacy mechanisms like RSA and ECDSA for digital identity verification.This paper proposes a quantum-resilient,blockchain-based identity verification framework designed to address critical challenges in privacy preservation,scalability,and post-quantum security.The proposed model integrates Post-quantum Cryptography(PQC),specifically lattice-based cryptographic primitives,with Decentralized Identifiers(DIDs)and Zero-knowledge Proofs(ZKPs)to ensure verifiability,anonymity,and resistance to quantum attacks.A dual-layer architecture is introduced,comprising an identity layer for credential generation and validation,and an application layer for DeFi protocol integration.To evaluate its performance,the framework is tested on multiple real-world DeFi platforms using metrics such as verification latency,throughput,attack resistance,energy efficiency,and quantum attack simulation.The results demonstrate that the proposed framework achieves 90%latency reduction and over 35%throughput improvement compared to traditional blockchain identity solutions.It also exhibits a high quantum resistance score(95/100),with successful secure verification under simulated quantum adversaries.The revocation mechanism—implemented using Merkle-tree-based proofs—achieves average response times under 40 ms,and the system maintains secure operations with energy consumption below 9 J per authentication cycle.Additionally,the paper presents a security and cost tradeoff analysis using ZKP schemes such as Bulletproofs and STARKs,revealing superior bits-per-byte efficiency and reduced proof sizes.Real-world adoption scenarios,including integration with six major DeFi protocols,indicate a 25%increase in verified users and a 15%improvement in Total Value Locked(TVL).The proposed solution is projected to remain secure until 2041(basic version)and 2043(advanced version),ensuring long-term sustainability and future-proofing against evolving quantum threats.This work establishes a scalable,privacy-preserving identity model that aligns with emerging post-quantum security standards for decentralized ecosystems.
基金supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project Number(PNURSP2025R97)Princess Nourah bint Abdulrahman University,Riyadh,Saudi Arabia。
文摘Blockchain Technology(BT)has emerged as a transformative solution for improving the efficacy,security,and transparency of supply chain intelligence.Traditional Supply Chain Management(SCM)systems frequently have problems such as data silos,a lack of visibility in real time,fraudulent activities,and inefficiencies in tracking and traceability.Blockchain’s decentralized and irreversible ledger offers a solid foundation for dealing with these issues;it facilitates trust,security,and the sharing of data in real-time among all parties involved.Through an examination of critical technologies,methodology,and applications,this paper delves deeply into computer modeling based-blockchain framework within supply chain intelligence.The effect of BT on SCM is evaluated by reviewing current research and practical applications in the field.As part of the process,we delved through the research on blockchain-based supply chain models,smart contracts,Decentralized Applications(DApps),and how they connect to other cutting-edge innovations like Artificial Intelligence(AI)and the Internet of Things(IoT).To quantify blockchain’s performance,the study introduces analytical models for efficiency improvement,security enhancement,and scalability,enabling computational assessment and simulation of supply chain scenarios.These models provide a structured approach to predicting system performance under varying parameters.According to the results,BT increases efficiency by automating transactions using smart contracts,increases security by using cryptographic techniques,and improves transparency in the supply chain by providing immutable records.Regulatory concerns,challenges with interoperability,and scalability all work against broad adoption.To fully automate and intelligently integrate blockchain with AI and the IoT,additional research is needed to address blockchain’s current limitations and realize its potential for supply chain intelligence.
基金supported in part by the IN2CCAM project that has received funding from the European Union's Horizon Europe research and innovation programme(101076791)the National Natural Science Foundation of China(62403378)the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBQN-0669)
文摘In this work, we address the codiagnosability analysis problem of a networked discrete event system under malicious attacks. The considered system is modeled by a labeled Petri net and is monitored by a series of sites, in which each site possesses its own set of sensors, without requiring communication among sites or to any coordinators. A net is said to be codiagnosable with respect to a fault if at least one site could deduce the occurrence of this fault within finite steps. In this context, we focus on a type of malicious attack that is called stealthy intermittent replacement attack. The stealthiness demands that the corrupted observations should be consistent with the system's normal behavior, while the intermittent replacement setting entails that the replaced transition labels must be recovered within a bounded of consecutive corrupted observations(called as K-corruption intermittent attack). Particularly, there exists a coordination between attackers that are separately effected on different sites, which holds the same corrupted observation for each common transition under attacks. From an attacker viewpoint, this work aims to design Kcorruption intermittent attacks for violating the codiagnosability of systems. For this purpose, we propose an attack automaton to analyze K-corruption intermittent attack for each site, and build a new structure called complete attack graph that is used to analyze all the potential attacked paths. Finally, an algorithm is inferred to obtain the K-corruption intermittent attacks, and examples are given to show the proposed attack strategy.
文摘Smart contracts on the Ethereum blockchain continue to revolutionize decentralized applications (dApps) by allowing for self-executing agreements. However, bad actors have continuously found ways to exploit smart contracts for personal financial gain, which undermines the integrity of the Ethereum blockchain. This paper proposes a computer program called SADA (Static and Dynamic Analyzer), a novel approach to smart contract vulnerability detection using multiple Large Language Model (LLM) agents to analyze and flag suspicious Solidity code for Ethereum smart contracts. SADA not only improves upon existing vulnerability detection methods but also paves the way for more secure smart contract development practices in the rapidly evolving blockchain ecosystem.
基金supported in part by National Key R&D Program of China(Grant No.2021YFB1714100)in part by the National Natural Science Foundation of China(NSFC)under Grant 62371239+5 种基金in part by the the Program of Science and Technology Cooperation of Nanjing with International/Hong Kong,Macao and Taiwan(Grant No.202401019)in part by the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515012407)in part by the the Research Center for FinTech and Digital-Intelligent Management at Shenzhen University,in part by the National Natural Science Foundation of China under Grant 62271192in part by the Equipment Pre-Research Joint Research Program of Ministry of Education under Grant 8091B032129in part by the Major Science and Technology Projects of Longmen Laboratory under Grant 231100220300 and 231100220200in part by the Central Plains Leading Talent in Scientific and Technological Innovation Program under Grant 244200510048.
文摘Traditional Internet of Things(IoT)architectures that rely on centralized servers for data management and decision-making are vulnerable to security threats and privacy leakage.To address this issue,blockchain has been advocated for decentralized data management in a tamper-resistance,traceable,and transparent manner.However,a major issue that hinders the integration of blockchain and IoT lies in that,it is rather challenging for resource-constrained IoT devices to perform computation-intensive blockchain consensuses such as Proof-of-Work(PoW).Furthermore,the incentive mechanism of PoW pushes lightweight IoT nodes to aggregate their computing power to increase the possibility of successful block generation.Nevertheless,this eventually leads to the formation of computing power alliances,and significantly compromises the decentralization and security of BlockChain-aided IoT(BC-IoT)networks.To cope with these issues,we propose a lightweight consensus protocol for BC-IoT,called Proof-of-Trusted-Work(PoTW).The goal of the proposed consensus is to disincentivize the centralization of computing power and encourage the independent participation of lightweight IoT nodes in blockchain consensus.First,we put forth an on-chain reputation evaluation rule and a reputation chain for PoTW to enable the verifiability and traceability of nodes’reputations based on their contributions of computing power to the blockchain consensus,and we incorporate the multi-level block generation difficulty as a rewards for nodes to accumulate reputations.Second,we model the block generation process of PoTW and analyze the block throughput using the continuous time Markov chain.Additionally,we define and optimize the relative throughput gain to quantify and maximize the capability of PoTW that suppresses the computing power centralization(i.e.,centralization suppression).Furthermore,we investigate the impact of the computing power of the computing power alliance and the levels of block generation difficulty on the centralization suppression capability of PoTW.Finally,simulation results demonstrate the consistency of the analytical results in terms of block throughput.In particular,the results show that PoTW effectively reduces the block generation proportion of the computing power alliance compared with PoW,while simultaneously improving that of individual lightweight nodes.This indicates that PoTW is capable of suppressing the centralization of computing power to a certain degree.Moreover,as the levels of block generation difficulty in PoTW increase,its centralization suppression capability strengthens.
文摘The proof-of-stake(PoS)mechanism is a consensus protocol within blockchain technology that determines the validation of transactions and the minting of new blocks based on the participant’s stake in the cryptocurrency network.In contrast to proof-of-work(PoW),which relies on computational power to validate transactions,PoS employs a deterministic and resourceefficient approach to elect validators.Whereas,an inherent risk of PoS is the potential for centralization among a small cohort of network participants possessing substantial stakes,jeopardizing system decentralization and posing security threats.To mitigate centralization issues within PoS,this study introduces an incentive-aligned mechanism named decentralized proof-of-stake(DePoS),wherein the second-largest stakeholder is chosen as the final validator with a higher probability.Integrated with the verifiable random function(VRF),DePoS rewards the largest stakeholder with uncertainty,thus disincentivizing stakeholders from accumulating the largest stake.Additionally,a dynamic evolutionary game model is innovatively developed to simulate the evolution of staking pools,thus facilitating the investigation of staking pool selection dynamics and equilibrium stability across PoS and DePoS systems.The findings demonstrate that DePoS generally fosters wealth decentralization by discouraging the accumulation of significant cryptocurrency holdings.Through theoretical analysis of stakeholder predilection in staking pool selection and the simulation of the evolutionary tendency in pool scale,this research demonstrates the comparative advantage in decentralization offered by DePoS over the conventional PoS.
基金supported by the Beijing Natural Science Foundation(L223025,4242003)Qin Xin Talents Cultivation Program of Beijing Information Science&Technology University(QXTCP B202405)。
文摘With the evolution of next-generation communication networks,ensuring robust Core Network(CN)architecture and data security has become paramount.This paper addresses critical vulnerabilities in the architecture of CN and data security by proposing a novel framework based on blockchain technology that is specifically designed for communication networks.Traditional centralized network architectures are vulnerable to Distributed Denial of Service(DDoS)attacks,particularly in roaming scenarios where there is also a risk of private data leakage,which imposes significant operational demands.To address these issues,we introduce the Blockchain-Enhanced Core Network Architecture(BECNA)and the Secure Decentralized Identity Authentication Scheme(SDIDAS).The BECNA utilizes blockchain technology to decentralize data storage,enhancing network security,stability,and reliability by mitigating Single Points of Failure(SPoF).The SDIDAS utilizes Decentralized Identity(DID)technology to secure user identity data and streamline authentication in roaming scenarios,significantly reducing the risk of data breaches during cross-network transmissions.Our framework employs Ethereum,free5GC,Wireshark,and UERANSIM tools to create a robust,tamper-evident system model.A comprehensive security analysis confirms substantial improvements in user privacy and network security.Simulation results indicate that our approach enhances communication CNs security and reliability,while also ensuring data security.
