In order to improve the bias stability of the micro-electro mechanical system（MEMS） gyroscope and reduce the impact on the bias from environmental temperature,a digital signal processing method is described for impr...In order to improve the bias stability of the micro-electro mechanical system（MEMS） gyroscope and reduce the impact on the bias from environmental temperature,a digital signal processing method is described for improving the accuracy of the drive phase in the gyroscope drive mode.Through the principle of bias signal generation,it can be concluded that the deviation of the drive phase is the main factor affecting the bias stability.To fulfill the purpose of precise drive phase control,a digital signal processing circuit based on the field-programmable gate array（FPGA） with the phase-lock closed-loop control method is described and a demodulation method for phase error suppression is given.Compared with the analog circuit,the bias drift is largely reduced in the new digital circuit and the bias stability is improved from 60 to 19 °/h.The new digital control method can greatly increase the drive phase accuracy,and thus improve the bias stability.展开更多
This review describes the investigations of oscillatory complex networks consisting of excitable nodes, focusing on the target wave patterns or say the target wave attractors. A method of dominant phase advanced drivi...This review describes the investigations of oscillatory complex networks consisting of excitable nodes, focusing on the target wave patterns or say the target wave attractors. A method of dominant phase advanced driving （DPAD） is introduced to reveal the dynamic structures in the networks supporting osciUations, such as the oscillation sources and the main excitation propagation paths from the sources to the whole networks. The target center nodes and their drivers are regarded as the key nodes which can completely determine the corresponding target wave patterns. Therefore, the center （say node A） and its driver （say node B） of a target wave can be used as a label, （A, B）, of the given target pattern. The label can give a clue to conveniently retrieve, suppress, and control the target waves. Statistical investigations, both theoretically from the label analysis and numerically from direct simulations of network dynamics, show that there exist huge numbers of target wave attractors in excitable complex networks if the system size is large, and all these attractors can be labeled and easily controlled based on the information given by the labels. The possible applications of the physical ideas and the mathematical methods about multiplicity and labelability of attractors to memory problems of neural networks are briefly discussed.展开更多
Two batches of Bi‐2212 precursor powder with Sr/Ca=2.24,2.33 were prepared by the spray pyrolysis tech-nology.Then two Bi‐2212 superconducting wires marked as Line4 and Line8‐2 were prepared by the above powders.Li...Two batches of Bi‐2212 precursor powder with Sr/Ca=2.24,2.33 were prepared by the spray pyrolysis tech-nology.Then two Bi‐2212 superconducting wires marked as Line4 and Line8‐2 were prepared by the above powders.Line4 with Sr/Ca=2.24 showed much higher phase purity,higher texture and its critical current density(J_(c))was 1.5 times that of Line8‐2 with Sr/Ca=2.33.Their micro‐structure evolution was scrutinized by quenching each wire at 7 instantaneous moments during the partial melting process(PMP).Bi‐2212 was found to decompose into(Sr,Ca)_(14)Cu_(24)O_(x)(14:24AEC),Bi_(9)Sr_(11)Ca_(5)O_(x)(9:16CF),Bi‐rich liquid Bi‐2212 and Bi‐rich solid Bi‐2212 at the initial stage of PMP.When Bi‐2212 began to solidify,the above four phases reacted to generate Bi‐2212.By analyzing the particle size,the content and the composition variation for 14:24AEC,9:16CF as well as the composition variation for Bi‐2212 matrix in above 7 moments of PMP,the phase evolu-tion’s difference between two wires was finally confirmed.The formation energy of 14:24AEC was smaller compared with 9:16CF,while 9:16CF was faster on dynamics.14:24AEC determined the whole synthetic reac-tion’s rate of Bi‐2212,and Sr/Ca as well as its value fluctuation in Bi‐2212 precursor powder can decide both the timeline and the driving force of PMP.A larger Sr/Ca in Line8‐2 made it melt earlier compared with Line4,which led to its earlier timeline during the melting stage of PMP.While the more consistent phase evolution’s pace between 14:24AEC and 9:16CF in Line4 finally contributed a larger Sr/Ca after solidification.Both the larger Sr/Ca and its larger fluctuation in Line4 finally contributed to its faster phase evolution’s pace,higher phase purity,better texture and higher J_(c).The deep logic driving the phase evolution mechanism in Bi‐2212 wires was disclosed for the first time,which will be very helpful to the future improvement of J_(c)for Bi‐2212 wires.展开更多
基金The National Natural Science Foundation of China (No.60974116)the Research Fund of Aeronautics Science (No. 20090869007)Specialized Research Fund for the Doctoral Program of Higher Education(No. 200802861063)
文摘In order to improve the bias stability of the micro-electro mechanical system（MEMS） gyroscope and reduce the impact on the bias from environmental temperature,a digital signal processing method is described for improving the accuracy of the drive phase in the gyroscope drive mode.Through the principle of bias signal generation,it can be concluded that the deviation of the drive phase is the main factor affecting the bias stability.To fulfill the purpose of precise drive phase control,a digital signal processing circuit based on the field-programmable gate array（FPGA） with the phase-lock closed-loop control method is described and a demodulation method for phase error suppression is given.Compared with the analog circuit,the bias drift is largely reduced in the new digital circuit and the bias stability is improved from 60 to 19 °/h.The new digital control method can greatly increase the drive phase accuracy,and thus improve the bias stability.
基金supported by the National Natural Science Foundation of China(Grant Nos.11174034,11135001,11205041,and 11305112)the Natural ScienceFoundation of Jiangsu Province,China(Grant No.BK20130282)
文摘This review describes the investigations of oscillatory complex networks consisting of excitable nodes, focusing on the target wave patterns or say the target wave attractors. A method of dominant phase advanced driving （DPAD） is introduced to reveal the dynamic structures in the networks supporting osciUations, such as the oscillation sources and the main excitation propagation paths from the sources to the whole networks. The target center nodes and their drivers are regarded as the key nodes which can completely determine the corresponding target wave patterns. Therefore, the center （say node A） and its driver （say node B） of a target wave can be used as a label, （A, B）, of the given target pattern. The label can give a clue to conveniently retrieve, suppress, and control the target waves. Statistical investigations, both theoretically from the label analysis and numerically from direct simulations of network dynamics, show that there exist huge numbers of target wave attractors in excitable complex networks if the system size is large, and all these attractors can be labeled and easily controlled based on the information given by the labels. The possible applications of the physical ideas and the mathematical methods about multiplicity and labelability of attractors to memory problems of neural networks are briefly discussed.
基金financially supported by the Key Research and Development Program of Shaanxi(Program No.2023‐YBGY‐428)the National natural Science foundation of China(No.52002333)+2 种基金the Science and Technology Planning Project in Weiyang District of Xi’an(No.202107)the National Key R&D Program of China(Grant No.2021YFB3800201)the National natural Science foundation of China(No.52277029).
文摘Two batches of Bi‐2212 precursor powder with Sr/Ca=2.24,2.33 were prepared by the spray pyrolysis tech-nology.Then two Bi‐2212 superconducting wires marked as Line4 and Line8‐2 were prepared by the above powders.Line4 with Sr/Ca=2.24 showed much higher phase purity,higher texture and its critical current density(J_(c))was 1.5 times that of Line8‐2 with Sr/Ca=2.33.Their micro‐structure evolution was scrutinized by quenching each wire at 7 instantaneous moments during the partial melting process(PMP).Bi‐2212 was found to decompose into(Sr,Ca)_(14)Cu_(24)O_(x)(14:24AEC),Bi_(9)Sr_(11)Ca_(5)O_(x)(9:16CF),Bi‐rich liquid Bi‐2212 and Bi‐rich solid Bi‐2212 at the initial stage of PMP.When Bi‐2212 began to solidify,the above four phases reacted to generate Bi‐2212.By analyzing the particle size,the content and the composition variation for 14:24AEC,9:16CF as well as the composition variation for Bi‐2212 matrix in above 7 moments of PMP,the phase evolu-tion’s difference between two wires was finally confirmed.The formation energy of 14:24AEC was smaller compared with 9:16CF,while 9:16CF was faster on dynamics.14:24AEC determined the whole synthetic reac-tion’s rate of Bi‐2212,and Sr/Ca as well as its value fluctuation in Bi‐2212 precursor powder can decide both the timeline and the driving force of PMP.A larger Sr/Ca in Line8‐2 made it melt earlier compared with Line4,which led to its earlier timeline during the melting stage of PMP.While the more consistent phase evolution’s pace between 14:24AEC and 9:16CF in Line4 finally contributed a larger Sr/Ca after solidification.Both the larger Sr/Ca and its larger fluctuation in Line4 finally contributed to its faster phase evolution’s pace,higher phase purity,better texture and higher J_(c).The deep logic driving the phase evolution mechanism in Bi‐2212 wires was disclosed for the first time,which will be very helpful to the future improvement of J_(c)for Bi‐2212 wires.
