放电室磁场的优化设计是离子推力器结构改进设计的关键技术之一,直接影响到推进剂电离效率和整机工作稳定性。针对深空探测等空间轨道任务对20 cm氙离子推力器应用需求,利用电磁体磁感应强度实时可调的优势,获得了给定工作模式下20 cm...放电室磁场的优化设计是离子推力器结构改进设计的关键技术之一,直接影响到推进剂电离效率和整机工作稳定性。针对深空探测等空间轨道任务对20 cm氙离子推力器应用需求,利用电磁体磁感应强度实时可调的优势,获得了给定工作模式下20 cm氙离子推力器放电室磁场最优构型及其磁感应强度的最佳分布。在此基础上,运用等效磁通理论,明确了产生相同磁场构型及其磁感应强度分布的永磁体结构尺寸。将20 cm氙离子推力器放电室磁场优化前后的性能进行对比,结果表明:在不改变整机结构的情况下,放电室磁场优化后推力可提升50%,由40 m N提高到60 m N,比冲提高到3 500 s,效率提高到65%。通过磁场优化,使得20 cm氙离子推力器具备了在40 m N和60 m N双模式工作的能力。研究为高效、稳定工作的离子推力器磁场优化提供方法。展开更多
The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of free...The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of freedom(DOF). In this work, an LQR control algorithm with superelement model is intended to solve this issue leading to the fact that LQR control algorithm can be used in large finite element(FE) model for structure. In proposed model, the Craig-Bampton(C-B) method, which is one of the component mode syntheses(CMS), is used to establish superelement modeling to reduce structure's DOF and applied to LQR control algorithm to calculate Kalman gain matrix and obtain control forces. And then, the control forces are applied to original structure to simulate the responses of structure by vibration control. And some examples are given. The results show the computational efficiency of proposed model using synthesized models is higher than that of the classical method of LQR control when the DOF of structure is large. And the accuracy of proposed model is well. Meanwhile, the results show that the proposed control has more effects of vibration absorption on the ground structures than underground structures.展开更多
In the field of analog VLSI design, current conveyors have reasonably established their identity as an important circuit design element. In the literature published during the past few years, numerous application have...In the field of analog VLSI design, current conveyors have reasonably established their identity as an important circuit design element. In the literature published during the past few years, numerous application have been reported which are based on a variety of current conveyors. In this paper, an oscillator circuit has been proposed. This oscillator is designed using a single positive type second generation current controlled current conveyor (CCCII+). A CCCII has parasitic input resistance on it’s current input node. This resistance could be exploited to reduce circuit complexities. Thus in this accord, a novel oscillator circuit is proposed which utilizes the parasitic resistance of the CCCII+ along with a few more passive components.展开更多
文摘放电室磁场的优化设计是离子推力器结构改进设计的关键技术之一,直接影响到推进剂电离效率和整机工作稳定性。针对深空探测等空间轨道任务对20 cm氙离子推力器应用需求,利用电磁体磁感应强度实时可调的优势,获得了给定工作模式下20 cm氙离子推力器放电室磁场最优构型及其磁感应强度的最佳分布。在此基础上,运用等效磁通理论,明确了产生相同磁场构型及其磁感应强度分布的永磁体结构尺寸。将20 cm氙离子推力器放电室磁场优化前后的性能进行对比,结果表明:在不改变整机结构的情况下,放电室磁场优化后推力可提升50%,由40 m N提高到60 m N,比冲提高到3 500 s,效率提高到65%。通过磁场优化,使得20 cm氙离子推力器具备了在40 m N和60 m N双模式工作的能力。研究为高效、稳定工作的离子推力器磁场优化提供方法。
基金Project(LZ2015022)supported by Educational Commission of Liaoning Province of ChinaProjects(51138001,51178081)supported by the National Natural Science Foundation of China+1 种基金Project(2013CB035905)supported by the Basic Research Program of ChinaProjects(DUT15LK34,DUT14QY10)supported by Fundamental Research Funds for the Central Universities,China
文摘The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of freedom(DOF). In this work, an LQR control algorithm with superelement model is intended to solve this issue leading to the fact that LQR control algorithm can be used in large finite element(FE) model for structure. In proposed model, the Craig-Bampton(C-B) method, which is one of the component mode syntheses(CMS), is used to establish superelement modeling to reduce structure's DOF and applied to LQR control algorithm to calculate Kalman gain matrix and obtain control forces. And then, the control forces are applied to original structure to simulate the responses of structure by vibration control. And some examples are given. The results show the computational efficiency of proposed model using synthesized models is higher than that of the classical method of LQR control when the DOF of structure is large. And the accuracy of proposed model is well. Meanwhile, the results show that the proposed control has more effects of vibration absorption on the ground structures than underground structures.
文摘In the field of analog VLSI design, current conveyors have reasonably established their identity as an important circuit design element. In the literature published during the past few years, numerous application have been reported which are based on a variety of current conveyors. In this paper, an oscillator circuit has been proposed. This oscillator is designed using a single positive type second generation current controlled current conveyor (CCCII+). A CCCII has parasitic input resistance on it’s current input node. This resistance could be exploited to reduce circuit complexities. Thus in this accord, a novel oscillator circuit is proposed which utilizes the parasitic resistance of the CCCII+ along with a few more passive components.
