Recent advances in integrating Digital Twins(DTs)with Heterogeneous Vehicular Networks(HetVNets)enhance decision-making and improve network performance.Additionally,developments in Mobile Edge Computing(MEC)support th...Recent advances in integrating Digital Twins(DTs)with Heterogeneous Vehicular Networks(HetVNets)enhance decision-making and improve network performance.Additionally,developments in Mobile Edge Computing(MEC)support the computational demands of DTs.However,the decentralized nature of MEC systems introduces security challenges and traditional HetVNets fail to efficiently integrate diverse computing and network resources,limiting their ability to handle services for vehicles.This paper presents a novel service request offloading framework for DT-HetVNets to address these issues.In this framework,we design utility functions for vehicles and infrastructures to maximize satisfaction of their requirements through data synchronization and decision-making between DTs and entities.Furthermore,we propose a new honestly based distributed PoA(HDPoA)via scalable work.The interactions between infrastructures and vehicles are modeled as a multi-leader multi-follower(MLMF)game,and we develop a dynamic iterative algorithm to achieve the Nash equilibrium(NE)of the proposed game-theoretic model.Experimental results validate the effectiveness and accuracy of our scheme.展开更多
Traditional Io T systems suffer from high equipment management costs and difficulty in trustworthy data sharing caused by centralization.Blockchain provides a feasible research direction to solve these problems. The m...Traditional Io T systems suffer from high equipment management costs and difficulty in trustworthy data sharing caused by centralization.Blockchain provides a feasible research direction to solve these problems. The main challenge at this stage is to integrate the blockchain from the resourceconstrained Io T devices and ensure the data of Io T system is credible. We provide a general framework for intelligent Io T data acquisition and sharing in an untrusted environment based on the blockchain, where gateways become Oracles. A distributed Oracle network based on Byzantine Fault Tolerant algorithm is used to provide trusted data for the blockchain to make intelligent Io T data trustworthy. An aggregation contract is deployed to collect data from various Oracle and share the credible data to all on-chain users. We also propose a gateway data aggregation scheme based on the REST API event publishing/subscribing mechanism which uses SQL to achieve flexible data aggregation. The experimental results show that the proposed scheme can alleviate the problem of limited performance of Io T equipment, make data reliable, and meet the diverse data needs on the chain.展开更多
The inherent stochasticity of mobile users’(MUs’)request moments and data processing durations,coupled with the aggregated bandwidth constraints during peak moments,often limits the performance of synchronous federa...The inherent stochasticity of mobile users’(MUs’)request moments and data processing durations,coupled with the aggregated bandwidth constraints during peak moments,often limits the performance of synchronous federated learning(FL)systems.To overcome these challenges,this paper proposes an incentive mechanism for asynchronous federated learning(AFL)systems within a Stackelberg game framework.In this model,MUs function as both consumers of communication resources and providers of computational services.Additionally,we derive a closed-form solution for determining the optimal number of local iterations and employ Newton’s method for numerical iteration to optimize the rewards for the cloud network controller(CNC).The numerical results demonstrate the effectiveness of the proposed scheme in enhancing system performance.展开更多
Copper,permalloy,cobalt,and silicon are the materials that have been widely utilised in magnetic devices.When the size of interest is down to the nanoscale,the inter-diffusion between certain materials becomes influen...Copper,permalloy,cobalt,and silicon are the materials that have been widely utilised in magnetic devices.When the size of interest is down to the nanoscale,the inter-diffusion between certain materials becomes influential.This paper studies the nanoscale friction characteristics between frictional pairs with and without inter-diffusion properties through the atomic force microscope.The distinct evolution features of nanoscale friction force when inter-diffusion is involved are discovered experimentally,which is also confirmed through theoretical analysis.Firstly,through the thin film deposition method,four pairs of contact materials(Cu–Ni_(81)Fe_(19),Si–Ni_(81)Fe_(19),Cu–Co,Cu–Si)are designed for friction tests,in which diffusion occurs at the interface of Cu–Ni_(81)Fe_(19)pair.Then,the effects of sliding velocity and loading force on the nano friction of each pair are measured.It is found that regardless of the diffusion phenomenon:(1)the adhesion force values exhibit a notable correlation to the values of the friction force;(2)the friction force in all four material pairs consistently increases with the growth of the normal loading force,although the growth rate may differ.In terms of the sliding velocity effect,the friction forces of immiscible materials(Si–Ni_(81)Fe_(19),Cu–Co,and Cu–Si)are found to increase with the increasing sliding velocity.However,the friction force of Cu–Ni_(81)Fe_(19),decreases with the increasing sliding velocity.Furthermore,a compositive friction model considering both the velocity and the normal force effect was proposed,which shows good agreement with the experimental results and explains the nano friction behaviour of both miscible and immiscible metals.展开更多
基金supported by the National Natural Science Foundation of China(No 62371250)the Natural Science Foundation on Frontier Leading Technology Basic Research Project of Jiangsu(No BK20212001)the Jiangsu Natural Science Foundation for Distinguished Young Scholars(No BK20220054).
文摘Recent advances in integrating Digital Twins(DTs)with Heterogeneous Vehicular Networks(HetVNets)enhance decision-making and improve network performance.Additionally,developments in Mobile Edge Computing(MEC)support the computational demands of DTs.However,the decentralized nature of MEC systems introduces security challenges and traditional HetVNets fail to efficiently integrate diverse computing and network resources,limiting their ability to handle services for vehicles.This paper presents a novel service request offloading framework for DT-HetVNets to address these issues.In this framework,we design utility functions for vehicles and infrastructures to maximize satisfaction of their requirements through data synchronization and decision-making between DTs and entities.Furthermore,we propose a new honestly based distributed PoA(HDPoA)via scalable work.The interactions between infrastructures and vehicles are modeled as a multi-leader multi-follower(MLMF)game,and we develop a dynamic iterative algorithm to achieve the Nash equilibrium(NE)of the proposed game-theoretic model.Experimental results validate the effectiveness and accuracy of our scheme.
基金supported by the open research fund of Key Lab of Broadband Wireless Communication and Sensor Network Technology(Nanjing University of Posts and Telecommunications),Ministry of Education(No.JZNY202114)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX210734).
文摘Traditional Io T systems suffer from high equipment management costs and difficulty in trustworthy data sharing caused by centralization.Blockchain provides a feasible research direction to solve these problems. The main challenge at this stage is to integrate the blockchain from the resourceconstrained Io T devices and ensure the data of Io T system is credible. We provide a general framework for intelligent Io T data acquisition and sharing in an untrusted environment based on the blockchain, where gateways become Oracles. A distributed Oracle network based on Byzantine Fault Tolerant algorithm is used to provide trusted data for the blockchain to make intelligent Io T data trustworthy. An aggregation contract is deployed to collect data from various Oracle and share the credible data to all on-chain users. We also propose a gateway data aggregation scheme based on the REST API event publishing/subscribing mechanism which uses SQL to achieve flexible data aggregation. The experimental results show that the proposed scheme can alleviate the problem of limited performance of Io T equipment, make data reliable, and meet the diverse data needs on the chain.
基金supported in part by the Joint Funds for the National Natural Science Foundation of China under Grant U24B20187the Natural Science Foundation on Frontier Leading Technology Basic Research Project of Jiangsu under Grant BK20212001+2 种基金the National Natural Science Foundation of China under Grants 92367302 and 62371250the Natural Science Foundation of the Jiangsu Higher Education Institutions of China under Grant 24KJA510008the Natural Science Foundation of Nanjing University of Posts and Telecommunications under Grant NY224113。
文摘The inherent stochasticity of mobile users’(MUs’)request moments and data processing durations,coupled with the aggregated bandwidth constraints during peak moments,often limits the performance of synchronous federated learning(FL)systems.To overcome these challenges,this paper proposes an incentive mechanism for asynchronous federated learning(AFL)systems within a Stackelberg game framework.In this model,MUs function as both consumers of communication resources and providers of computational services.Additionally,we derive a closed-form solution for determining the optimal number of local iterations and employ Newton’s method for numerical iteration to optimize the rewards for the cloud network controller(CNC).The numerical results demonstrate the effectiveness of the proposed scheme in enhancing system performance.
基金the National Natural Science Foundation of China(No.52171193)China Postdoctoral Science Foundation(No.2019M652564)Henan Postdoctoral Science Foundation(No.19030013)。
文摘Copper,permalloy,cobalt,and silicon are the materials that have been widely utilised in magnetic devices.When the size of interest is down to the nanoscale,the inter-diffusion between certain materials becomes influential.This paper studies the nanoscale friction characteristics between frictional pairs with and without inter-diffusion properties through the atomic force microscope.The distinct evolution features of nanoscale friction force when inter-diffusion is involved are discovered experimentally,which is also confirmed through theoretical analysis.Firstly,through the thin film deposition method,four pairs of contact materials(Cu–Ni_(81)Fe_(19),Si–Ni_(81)Fe_(19),Cu–Co,Cu–Si)are designed for friction tests,in which diffusion occurs at the interface of Cu–Ni_(81)Fe_(19)pair.Then,the effects of sliding velocity and loading force on the nano friction of each pair are measured.It is found that regardless of the diffusion phenomenon:(1)the adhesion force values exhibit a notable correlation to the values of the friction force;(2)the friction force in all four material pairs consistently increases with the growth of the normal loading force,although the growth rate may differ.In terms of the sliding velocity effect,the friction forces of immiscible materials(Si–Ni_(81)Fe_(19),Cu–Co,and Cu–Si)are found to increase with the increasing sliding velocity.However,the friction force of Cu–Ni_(81)Fe_(19),decreases with the increasing sliding velocity.Furthermore,a compositive friction model considering both the velocity and the normal force effect was proposed,which shows good agreement with the experimental results and explains the nano friction behaviour of both miscible and immiscible metals.
