In order to achieve the model-based fault monitoring and diagnosis,an accurate model for the rotor system is necessary to locate and quantify faults.Since the dynamic characteristics of a blade-rotor system is influen...In order to achieve the model-based fault monitoring and diagnosis,an accurate model for the rotor system is necessary to locate and quantify faults.Since the dynamic characteristics of a blade-rotor system is influenced by foundation flexibility,the modeling and dynamic analyses on the foundation were sequentially investigated.Firstly,the effect of element size on the model convergence was investigated using the forward difference quotient as the slope of the frequency difference,which found that the model converged when the element size refined to 4mm.Secondly,a modal analysis and a harmonic response analysis were performed to obtain the dynamic characteristics of the foundation structure.Finally,an optimization to the foundation utilizing an additional stiffener was conducted to reduce the foundation response and make the critical speed far away from the working frequency band of 20—50Hz.展开更多
A load-balancing scheme for IEEE 802.11 WLANs based on cooperative game theory is presented.A coalition among the access points（APs） with overlapping coverage is formed to share the network load through a game.First...A load-balancing scheme for IEEE 802.11 WLANs based on cooperative game theory is presented.A coalition among the access points（APs） with overlapping coverage is formed to share the network load through a game.Firstly, the candidate APs submit their load-competing strategies（i.e., the amount of user traffic they can admit in an AC/game period） to the control AP.Secondly, the control AP solves the game by the method of shapley value, which is the maximum traffic allocated to each AP in an AC/game period.Finally, the game is repeated periodically to distribute the traffic load among the APs.Simulation results show that the proposed game can balance the network load effectively compared with the IEEE 802.11 standard balancing solution.展开更多
基金supported by the National Key Research and Development Plan(No.2016YFF0203300)
文摘In order to achieve the model-based fault monitoring and diagnosis,an accurate model for the rotor system is necessary to locate and quantify faults.Since the dynamic characteristics of a blade-rotor system is influenced by foundation flexibility,the modeling and dynamic analyses on the foundation were sequentially investigated.Firstly,the effect of element size on the model convergence was investigated using the forward difference quotient as the slope of the frequency difference,which found that the model converged when the element size refined to 4mm.Secondly,a modal analysis and a harmonic response analysis were performed to obtain the dynamic characteristics of the foundation structure.Finally,an optimization to the foundation utilizing an additional stiffener was conducted to reduce the foundation response and make the critical speed far away from the working frequency band of 20—50Hz.
基金supported by the Aviation Science Fund (20080196005)
文摘A load-balancing scheme for IEEE 802.11 WLANs based on cooperative game theory is presented.A coalition among the access points（APs） with overlapping coverage is formed to share the network load through a game.Firstly, the candidate APs submit their load-competing strategies（i.e., the amount of user traffic they can admit in an AC/game period） to the control AP.Secondly, the control AP solves the game by the method of shapley value, which is the maximum traffic allocated to each AP in an AC/game period.Finally, the game is repeated periodically to distribute the traffic load among the APs.Simulation results show that the proposed game can balance the network load effectively compared with the IEEE 802.11 standard balancing solution.
