现代战术网中的业务越来越复杂,现有的网络控制方案难以有效支持。软件定义网络(Software Defined Network,SDN)架构可以提高战术网灵活性,但由于战术网脆弱的无线环境特征及SDN的集中式控制特点,该架构存在很高的单点故障风险,控制信...现代战术网中的业务越来越复杂,现有的网络控制方案难以有效支持。软件定义网络(Software Defined Network,SDN)架构可以提高战术网灵活性,但由于战术网脆弱的无线环境特征及SDN的集中式控制特点,该架构存在很高的单点故障风险,控制信道的失效会导致整个网络崩溃。针对这一问题,提出了一种基于协议无感知转发(Protocol Oblivious Forwarding,POF)的动态可伸缩控制方案。采用带内带外混合控制的方法,可以在环境高度动态的战术网中实现韧性控制。当带外控制信道失效后,网络可以基于带内控制与数据平面自定义协议相结合的方式,继续维持一定的网络功能。实验结果表明,本方案对于不稳定的战术网有较强的适应能力,在带外控制失效信道时仍能保障网络可用并使时延保持在0.1 s左右的范围。展开更多
软件定义网络(software defined networking,SDN)通过构建独立的控制平面,极大地降低了网络设备及管理的复杂性。但在大规模广域网部署中,这种逻辑集中的方法在性能和扩展性方面存在诸多限制。因此控制平面多控制器的部署是一个非常重...软件定义网络(software defined networking,SDN)通过构建独立的控制平面,极大地降低了网络设备及管理的复杂性。但在大规模广域网部署中,这种逻辑集中的方法在性能和扩展性方面存在诸多限制。因此控制平面多控制器的部署是一个非常重要的任务,其可以通过配置有限的资源来满足多样化需求。这些需求包括延迟限制、容错能力和负载均衡。提出一种控制器部署方法,该方法用于在给定的网络拓扑中完成控制器位置的部署。针对该部署方法设计了两种算法来分别实现控制器间负载均衡和控制器池内控制器数目的动态伸缩,提高网络资源利用率。仿真结果表明,相较LG方法,该方案在完成部署任务的同时,能够减少系统管理开销。展开更多
The control method for machining non-cylinder pin hole of piston was studied systematically. A new method was presented by embedding giant magnetostrictive material (GMM) into the tool bar proper position. The model i...The control method for machining non-cylinder pin hole of piston was studied systematically. A new method was presented by embedding giant magnetostrictive material (GMM) into the tool bar proper position. The model is established to characterize the relation between control current of coil and deformation of tool rod. A series of tests on deformation of giant magnetostrictive tool bar were done and the results validated the feasibility of the principle. The methods of measuring magne- tostrictive coefficient of rare earth GMM were analyzed. The measuring device with the bias field and prestress was designed. A series of experiments were done to test magnetostrictive coefficient. Experimental results supplied accurate characteristic pa- rameter for designing application device of GMM. The constitution of the developed control system made up of displacement detection and temperature detection for thermal deformation compensation was also introduced. The developed machine tool for boring the non-cylinder pin hole of piston has the micron order accuracy. This control method can be applied to other areas for machining precision or complex parts.展开更多
Differential evolution(DE) demonstrates good convergence performance,but it is difficult to choose trial vector generation strategies and associated control parameter values.An improved method,self-adapting scalable D...Differential evolution(DE) demonstrates good convergence performance,but it is difficult to choose trial vector generation strategies and associated control parameter values.An improved method,self-adapting scalable DE(SSDE) algorithm,is proposed.Trial vector generation strategies and crossover probability are respectively self-adapted by two operators in this algorithm.Meanwhile,to enhance the convergence rate,vectors selected randomly with the optimal fitness values are introduced to guide searching direction.Benchmark problems are used to verify this algorithm.Compared with other well-known DE algorithms,experiment results indicate that this algorithm is better than other DE algorithms in terms of convergence rate and quality of optimization.展开更多
Solar sail is a new type of spacecraft for deep space exploration,which flies by the pressure of sunlight.The attitude of the sail determines its orbit,so altitude control plays an important role in the mission.Howeve...Solar sail is a new type of spacecraft for deep space exploration,which flies by the pressure of sunlight.The attitude of the sail determines its orbit,so altitude control plays an important role in the mission.However,the large flexible structure leads to some difficulty in attitude control.This paper establishes the reduced dynamic model of a flexible solar sail with foreshortening deformation,and coupling with its attitude and vibration.As usual,large angle maneuvering will lead to the vibration of flexible structure,so the time optimal control of solar sail maneuvering is considered.Bang-Bang control of the solar sail generates large amplitude and sustained vibration,while the combined control based on input shaping can eliminate the vibration efficiently.With the comparison of two reduced models,it is demonstrated that the choice of two models depends on the attention to the stretching deformation.展开更多
文摘软件定义网络(software defined networking,SDN)通过构建独立的控制平面,极大地降低了网络设备及管理的复杂性。但在大规模广域网部署中,这种逻辑集中的方法在性能和扩展性方面存在诸多限制。因此控制平面多控制器的部署是一个非常重要的任务,其可以通过配置有限的资源来满足多样化需求。这些需求包括延迟限制、容错能力和负载均衡。提出一种控制器部署方法,该方法用于在给定的网络拓扑中完成控制器位置的部署。针对该部署方法设计了两种算法来分别实现控制器间负载均衡和控制器池内控制器数目的动态伸缩,提高网络资源利用率。仿真结果表明,相较LG方法,该方案在完成部署任务的同时,能够减少系统管理开销。
基金Project supported by the National Natural Science Foundation of China (No. 50575205) and the Natural Science Foundation of Zheji-ang Province (Nos. Y104243 and Y105686), China
文摘The control method for machining non-cylinder pin hole of piston was studied systematically. A new method was presented by embedding giant magnetostrictive material (GMM) into the tool bar proper position. The model is established to characterize the relation between control current of coil and deformation of tool rod. A series of tests on deformation of giant magnetostrictive tool bar were done and the results validated the feasibility of the principle. The methods of measuring magne- tostrictive coefficient of rare earth GMM were analyzed. The measuring device with the bias field and prestress was designed. A series of experiments were done to test magnetostrictive coefficient. Experimental results supplied accurate characteristic pa- rameter for designing application device of GMM. The constitution of the developed control system made up of displacement detection and temperature detection for thermal deformation compensation was also introduced. The developed machine tool for boring the non-cylinder pin hole of piston has the micron order accuracy. This control method can be applied to other areas for machining precision or complex parts.
基金National Natural Science Foundation of China (No. 70971020)
文摘Differential evolution(DE) demonstrates good convergence performance,but it is difficult to choose trial vector generation strategies and associated control parameter values.An improved method,self-adapting scalable DE(SSDE) algorithm,is proposed.Trial vector generation strategies and crossover probability are respectively self-adapted by two operators in this algorithm.Meanwhile,to enhance the convergence rate,vectors selected randomly with the optimal fitness values are introduced to guide searching direction.Benchmark problems are used to verify this algorithm.Compared with other well-known DE algorithms,experiment results indicate that this algorithm is better than other DE algorithms in terms of convergence rate and quality of optimization.
文摘Solar sail is a new type of spacecraft for deep space exploration,which flies by the pressure of sunlight.The attitude of the sail determines its orbit,so altitude control plays an important role in the mission.However,the large flexible structure leads to some difficulty in attitude control.This paper establishes the reduced dynamic model of a flexible solar sail with foreshortening deformation,and coupling with its attitude and vibration.As usual,large angle maneuvering will lead to the vibration of flexible structure,so the time optimal control of solar sail maneuvering is considered.Bang-Bang control of the solar sail generates large amplitude and sustained vibration,while the combined control based on input shaping can eliminate the vibration efficiently.With the comparison of two reduced models,it is demonstrated that the choice of two models depends on the attention to the stretching deformation.
