With the development of vehicle networks and the construction of roadside units,Vehicular Ad Hoc Networks(VANETs)are increasingly promoting cooperative computing patterns among vehicles.Vehicular edge computing(VEC)of...With the development of vehicle networks and the construction of roadside units,Vehicular Ad Hoc Networks(VANETs)are increasingly promoting cooperative computing patterns among vehicles.Vehicular edge computing(VEC)offers an effective solution to mitigate resource constraints by enabling task offloading to edge cloud infrastructure,thereby reducing the computational burden on connected vehicles.However,this sharing-based and distributed computing paradigm necessitates ensuring the credibility and reliability of various computation nodes.Existing vehicular edge computing platforms have not adequately considered themisbehavior of vehicles.We propose a practical task offloading algorithm based on reputation assessment to address the task offloading problem in vehicular edge computing under an unreliable environment.This approach integrates deep reinforcement learning and reputation management to address task offloading challenges.Simulation experiments conducted using Veins demonstrate the feasibility and effectiveness of the proposed method.展开更多
The frequent use of location query services in location-based services will come out a large amount of space-time data related to users. Attackers infer information of location or track based on these rich background ...The frequent use of location query services in location-based services will come out a large amount of space-time data related to users. Attackers infer information of location or track based on these rich background knowledge. Therefore, aiming at the problem of trajectory privacy, the context adds instant traffic monitoring based on user behavior patterns, trajectory similarity and other background information. According to the idea of k anonymity, proposed a method combined with traffic condition to protect the trajectory privacy. First, the user randomly selects a time point of the real trajectory to rotate to generate dummy trajectory, and then repeat the above process on the real trajectory and dummy trajectory. Up to the generation of k −1 dummy trajectory, and according to the actual road conditions and trajectory leakage probability, traversing dummy trajectory to adjust. Finally, it is further proved through experiments that the method will be more efficient and protect privacy well.展开更多
Social network contains the interaction between social members, which constitutes the structure and attribute of social network. The interactive relationship of social network contains a lot of personal privacy inform...Social network contains the interaction between social members, which constitutes the structure and attribute of social network. The interactive relationship of social network contains a lot of personal privacy information. The direct release of social network data will cause the disclosure of privacy information. Aiming at the dynamic characteristics of social network data release, a new dynamic social network data publishing method based on differential privacy was proposed. This method was consistent with differential privacy. It is named DDPA (Dynamic Differential Privacy Algorithm). DDPA algorithm is an improvement of privacy protection algorithm in static social network data publishing. DDPA adds noise which follows Laplace to network edge weights. DDPA identifies the edge weight information that changes as the number of iterations increases, adding the privacy protection budget. Through experiments on real data sets, the results show that the DDPA algorithm satisfies the user’s privacy requirement in social network. DDPA reduces the execution time brought by iterations and reduces the information loss rate of graph structure.展开更多
The uniaxial ratcheting behaviors of several metals with different crystal structures or values of fault energy were observed by the stress-controlled cyclic tests at room temperature. The prescribed metals included 3...The uniaxial ratcheting behaviors of several metals with different crystal structures or values of fault energy were observed by the stress-controlled cyclic tests at room temperature. The prescribed metals included 316L stainless steel, pure copper, pure aluminum, and ordinary 20# carbon steel. The effects of applied mean stress, stress amplitude and stress ratio on the uniaxial ratcheting were also investigated. The observations show that different crystal structures or values of fault energy result in more or less different ratcheting behaviors for the prescribed metals. The different ratcheting behaviors are partially caused by the variation of dislocation mobility.展开更多
In arid and semi-arid sand dune ecosystems,belowground bud bank plays an important role in population regeneration and vegetation restoration.However,the responses of belowground bud bank size and composition to sand ...In arid and semi-arid sand dune ecosystems,belowground bud bank plays an important role in population regeneration and vegetation restoration.However,the responses of belowground bud bank size and composition to sand burial and its induced changes in soil environmental factors have been rarely studied.In arid sand dunes of Northwestern China,we investigated belowground bud bank size and composition of the typical rhizomatous psammophyte Psammochloa villosa as well as three key soil environmental factors(soil moisture,total carbon and total nitrogen)under different depths of sand burial.Total buds and rhizome buds increased significantly with increasing burial depth,whereas tiller buds first increased and then decreased,with a peak value at the depth of 20-30 cm.Soil moisture increased significantly with sand burial depth,and was positively correlated with the number of all buds and rhizome buds.Soil total carbon concentration first increased and then decreased with sand burial depth,and total nitrogen concentration was significantly lower under deep sand burial than those at shallow depths,and only the number of tiller buds was positively correlated with soil total nitrogen concentration.These results indicate that soil moisture rather than soil nutrient might regulate the belowground bud bank of P.villosa,and that clonal psammophytes could regulate their belowground bud bank in response to sand burial and the most important environmental stress(i.e.,soil moisture).These responses,as the key adaptive strategy,may ensure clonal plant population regeneration and vegetation restoration in arid sand dunes.展开更多
Trade-offs have long been recognized as a crucial ecological strategy for plant species in response to environmental stresses and disturbances.However,it remains unclear whether trade-offs exist among different struct...Trade-offs have long been recognized as a crucial ecological strategy for plant species in response to environmental stresses and disturbances.However,it remains unclear whether trade-offs exist among different structures(or functions)of clonal plants in response to aeolian activities in sandy environments.We examined the growth(reproductive vs.vegetative),reproduction(sexual vs.asexual),and bud bank(tiller buds and rhizome buds,representing vertical and horizontal growth potential)characteristics of two dominant rhizomatous grasses(Psammochloa villosa and Phragmites australis)in the arid sand dunes of northwestern China.Our results showed that these two rhizomatous clonal species exhibited significant trade-offs in their adaptation strategies in response to changes in sand burial depth.Specifically,as sand burial depth increased,the clonal species tended to reduce their reproductive growth,sexual reproductive capacity,and horizontal growth potential,as evidenced by reductions in reproductive ramet number and proportion,panicles number,biomass,and their proportions,as well as rhizome bud number,biomass,and their proportions.Conversely,they increased vegetative growth,reproduction,and vertical growth potential,as evidenced by enhancements in vegetative ramet number and proportion,belowground bud number,biomass,and their proportions,and in tiller bud number,biomass,and their proportions.Our study underscores the importance of trade-offs in the adaptation strategies of rhizomatous clonal species in sandy environments where drought stress and aeolian disturbance coexist.Those trade-offs could ensure the population persistence and stability of pioneering psammophytes in sand dunes,which should be considered during sand-fixing and vegetation restoration efforts in arid sand dunes.展开更多
基金supported by the Open Foundation of Henan Key Laboratory of Cyberspace Situation Awareness(No.HNTS2022020)the Science and Technology Research Program of Henan Province of China(232102210134,182102210130)Key Research Projects of Henan Provincial Universities(25B520005).
文摘With the development of vehicle networks and the construction of roadside units,Vehicular Ad Hoc Networks(VANETs)are increasingly promoting cooperative computing patterns among vehicles.Vehicular edge computing(VEC)offers an effective solution to mitigate resource constraints by enabling task offloading to edge cloud infrastructure,thereby reducing the computational burden on connected vehicles.However,this sharing-based and distributed computing paradigm necessitates ensuring the credibility and reliability of various computation nodes.Existing vehicular edge computing platforms have not adequately considered themisbehavior of vehicles.We propose a practical task offloading algorithm based on reputation assessment to address the task offloading problem in vehicular edge computing under an unreliable environment.This approach integrates deep reinforcement learning and reputation management to address task offloading challenges.Simulation experiments conducted using Veins demonstrate the feasibility and effectiveness of the proposed method.
文摘The frequent use of location query services in location-based services will come out a large amount of space-time data related to users. Attackers infer information of location or track based on these rich background knowledge. Therefore, aiming at the problem of trajectory privacy, the context adds instant traffic monitoring based on user behavior patterns, trajectory similarity and other background information. According to the idea of k anonymity, proposed a method combined with traffic condition to protect the trajectory privacy. First, the user randomly selects a time point of the real trajectory to rotate to generate dummy trajectory, and then repeat the above process on the real trajectory and dummy trajectory. Up to the generation of k −1 dummy trajectory, and according to the actual road conditions and trajectory leakage probability, traversing dummy trajectory to adjust. Finally, it is further proved through experiments that the method will be more efficient and protect privacy well.
文摘Social network contains the interaction between social members, which constitutes the structure and attribute of social network. The interactive relationship of social network contains a lot of personal privacy information. The direct release of social network data will cause the disclosure of privacy information. Aiming at the dynamic characteristics of social network data release, a new dynamic social network data publishing method based on differential privacy was proposed. This method was consistent with differential privacy. It is named DDPA (Dynamic Differential Privacy Algorithm). DDPA algorithm is an improvement of privacy protection algorithm in static social network data publishing. DDPA adds noise which follows Laplace to network edge weights. DDPA identifies the edge weight information that changes as the number of iterations increases, adding the privacy protection budget. Through experiments on real data sets, the results show that the DDPA algorithm satisfies the user’s privacy requirement in social network. DDPA reduces the execution time brought by iterations and reduces the information loss rate of graph structure.
基金support of the National Natural Science Foundation of China (Grant No. 10772153)
文摘The uniaxial ratcheting behaviors of several metals with different crystal structures or values of fault energy were observed by the stress-controlled cyclic tests at room temperature. The prescribed metals included 316L stainless steel, pure copper, pure aluminum, and ordinary 20# carbon steel. The effects of applied mean stress, stress amplitude and stress ratio on the uniaxial ratcheting were also investigated. The observations show that different crystal structures or values of fault energy result in more or less different ratcheting behaviors for the prescribed metals. The different ratcheting behaviors are partially caused by the variation of dislocation mobility.
基金This work was financially supported by the National Natural Science Foundation of China(41877542,41907411).
文摘In arid and semi-arid sand dune ecosystems,belowground bud bank plays an important role in population regeneration and vegetation restoration.However,the responses of belowground bud bank size and composition to sand burial and its induced changes in soil environmental factors have been rarely studied.In arid sand dunes of Northwestern China,we investigated belowground bud bank size and composition of the typical rhizomatous psammophyte Psammochloa villosa as well as three key soil environmental factors(soil moisture,total carbon and total nitrogen)under different depths of sand burial.Total buds and rhizome buds increased significantly with increasing burial depth,whereas tiller buds first increased and then decreased,with a peak value at the depth of 20-30 cm.Soil moisture increased significantly with sand burial depth,and was positively correlated with the number of all buds and rhizome buds.Soil total carbon concentration first increased and then decreased with sand burial depth,and total nitrogen concentration was significantly lower under deep sand burial than those at shallow depths,and only the number of tiller buds was positively correlated with soil total nitrogen concentration.These results indicate that soil moisture rather than soil nutrient might regulate the belowground bud bank of P.villosa,and that clonal psammophytes could regulate their belowground bud bank in response to sand burial and the most important environmental stress(i.e.,soil moisture).These responses,as the key adaptive strategy,may ensure clonal plant population regeneration and vegetation restoration in arid sand dunes.
基金supported by the National Natural Science Foundation of China(41877542)the Key Scientific and Technological Project of Henan Province(232102320245).
文摘Trade-offs have long been recognized as a crucial ecological strategy for plant species in response to environmental stresses and disturbances.However,it remains unclear whether trade-offs exist among different structures(or functions)of clonal plants in response to aeolian activities in sandy environments.We examined the growth(reproductive vs.vegetative),reproduction(sexual vs.asexual),and bud bank(tiller buds and rhizome buds,representing vertical and horizontal growth potential)characteristics of two dominant rhizomatous grasses(Psammochloa villosa and Phragmites australis)in the arid sand dunes of northwestern China.Our results showed that these two rhizomatous clonal species exhibited significant trade-offs in their adaptation strategies in response to changes in sand burial depth.Specifically,as sand burial depth increased,the clonal species tended to reduce their reproductive growth,sexual reproductive capacity,and horizontal growth potential,as evidenced by reductions in reproductive ramet number and proportion,panicles number,biomass,and their proportions,as well as rhizome bud number,biomass,and their proportions.Conversely,they increased vegetative growth,reproduction,and vertical growth potential,as evidenced by enhancements in vegetative ramet number and proportion,belowground bud number,biomass,and their proportions,and in tiller bud number,biomass,and their proportions.Our study underscores the importance of trade-offs in the adaptation strategies of rhizomatous clonal species in sandy environments where drought stress and aeolian disturbance coexist.Those trade-offs could ensure the population persistence and stability of pioneering psammophytes in sand dunes,which should be considered during sand-fixing and vegetation restoration efforts in arid sand dunes.
