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A step to the decentralized real-time timekeeping network
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作者 王芳敏 陈雨锋 +4 位作者 周建华 蔺玉亭 杨军 王波 王力军 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期183-191,共9页
The composite time scale(CTS) provides an accurate and stable time-frequency reference for modern science and technology. Conventional CTS always features a centralized network topology, which means that the CTS is ac... The composite time scale(CTS) provides an accurate and stable time-frequency reference for modern science and technology. Conventional CTS always features a centralized network topology, which means that the CTS is accompanied by a local master clock. This largely restricts the stability and reliability of the CTS. We simulate the restriction and analyze the influence of the master clock on the CTS. It proves that the CTS's long-term stability is also positively related to that of the master clock, until the region dominated by the frequency drift of the H-maser(averaging time longer than ~10~5s).Aiming at this restriction, a real-time clock network is utilized. Based on the network, a real-time CTS referenced by a stable remote master clock is achieved. The experiment comparing two real-time CTSs referenced by a local and a remote master clock respectively reveals that under open-loop steering, the stability of the CTS is improved by referencing to a remote and more stable master clock instead of a local and less stable master clock. In this way, with the help of the proposed scheme, the CTS can be referenced to the most stable master clock within the network in real time, no matter whether it is local or remote, making democratic polycentric timekeeping possible. 展开更多
关键词 frequency synchronization network composite time scale frequency stability democratic timekeeping
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Synchronization of networked multibody systems using fundamental equation of mechanics 被引量:2
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作者 Jun LIU Jinchen JI Jin ZHOU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2016年第5期555-572,共18页
From the analytical dynamics point of view, this paper develops an optimal control framework to synchronize networked multibody systems using the fundamental equation of mechanics. A novel robust control law derived f... From the analytical dynamics point of view, this paper develops an optimal control framework to synchronize networked multibody systems using the fundamental equation of mechanics. A novel robust control law derived from the framework is then used to achieve complete synchronization of networked identical or non-identical multibody systems formulated with Lagrangian dynamics. A distinctive feature of the developed control strategy is the introduction of network structures into the control requirement. The control law consists of two components, the first describing the architecture of the network and the second denoting an active feedback control strategy. A corresponding stability analysis is performed by the algebraic graph theory. A representative network composed of ten identical or non-identical gyroscopes is used as an illustrative example. Numerical simulation of the systems with three kinds of network structures, including global coupling, nearest-neighbour, and small-world networks, is given to demonstrate effectiveness of the proposed control methodology. 展开更多
关键词 fundamental equation of mechanics analytical dynamics synchronization networked multibody system gyrodynamics coordinate control
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Effects of Reduced Frequency on Network Configuration and Synchronization Transition 被引量:2
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作者 朱留华 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第5期14-17,共4页
Synchronization of networked phase oscillators depends essentially on the correlation between the topological structure of the graph and the dynamical property of the elements. We propose the concept of 'reduced freq... Synchronization of networked phase oscillators depends essentially on the correlation between the topological structure of the graph and the dynamical property of the elements. We propose the concept of 'reduced frequency', a measure which can quantify natural frequencies of each pair of oscillators. Then we introduce an evolving network whose linking rules are controlled by its own dynamical property. The simulation results indicate that when the linking probability positively correlates with the reduced frequency, the network undergoes a first-order phase transition. Meanwhile, we discuss the circumstance under which an explosive synchronization can be ignited. The numerical results show that the peculiar butterfly shape correlation between frequencies and degrees of the nodes contributes to an explosive synchronization transition. 展开更多
关键词 of WORK as IT Effects of Reduced Frequency on network Configuration and synchronization Transition IS that
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The Importance of Time Synchronization in the Local Networks of the Science and Application Center for Lunar and Deep-space Exploration 被引量:1
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作者 LIUGuoping OUYANGZiyuan +1 位作者 LIChunlai LIUJianfeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第5期1104-1108,共5页
The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have the... The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have their own local networks and interconnect with each other through access to the core data network. This paper describes the clock drift in the computer and other networked devices building up the infrastructure of the above local networks. The network time variance of the stochastic model is also estimated. The poor precision of network synchronization will bring about potential hazards to the network operation and application running in the networks, which is clarified in the present paper. At the end of the paper, a cost-effective and feasible solution is proposed based on the Global Position System (GPS) and the Network Time Protocol (NTP). 展开更多
关键词 SACLuDE clock drift network time variance network synchronization GPS NTP
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Exponential networked synchronization of master-slave chaotic systems with timevarying communication topologies 被引量:1
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作者 杨东升 刘振伟 +1 位作者 赵琰 刘兆冰 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第4期151-158,共8页
The networked synchronization problem of a class of master-slave chaotic systems with time-varying communication topologies is investigated in this paper. Based on algebraic graph theory and matrix theory, a simple li... The networked synchronization problem of a class of master-slave chaotic systems with time-varying communication topologies is investigated in this paper. Based on algebraic graph theory and matrix theory, a simple linear state feedback controller is designed to synchronize the master chaotic system and the slave chaotic systems with a time- varying communication topology connection. The exponential stability of the closed-loop networked synchronization error system is guaranteed by applying Lyapunov stability theory. The derived novel criteria are in the form of linear matrix inequalities (LMIs), which are easy to examine and tremendously reduce the computation burden from the feedback matrices. This paper provides an alternative networked secure communication scheme which can be extended conveniently. An illustrative example is given to demonstrate the effectiveness of the proposed networked synchronization method. 展开更多
关键词 exponential networked synchronization master-slave chaotic systems algebraic graph theory communication topology
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Free-matrix-based time-dependent discontinuous Lyapunov functional for synchronization of delayed neural networks with sampled-data control 被引量:1
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作者 王炜 曾红兵 Kok-Lay Teo 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第11期127-134,共8页
This paper is concerned with the synchronization of delayed neural networks via sampled-data control. A new technique, namely, the free-matrix-based time-dependent discontinuous Lyapunov functional approach, is adopte... This paper is concerned with the synchronization of delayed neural networks via sampled-data control. A new technique, namely, the free-matrix-based time-dependent discontinuous Lyapunov functional approach, is adopted in constructing the Lyapunov functional, which takes advantage of the sampling characteristic of sawtooth input delay. Based on this discontinuous Lyapunov functional, some less conservative synchronization criteria are established to ensure that the slave system is synchronous with the master system. The desired sampled-data controller can be obtained through the use of the linear matrix inequality(LMI) technique. Finally, two numerical examples are provided to demonstrate the effectiveness and the improvements of the proposed methods. 展开更多
关键词 neural networks synchronization sampled-data control free-matrix-based inequality
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Synchronization investigation of the network group constituted by the nearest neighbor networks under inner and outer synchronous couplings
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作者 李亭亭 李成仁 +4 位作者 王晨 何芳君 周光冶 孙景昌 韩非 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第12期572-576,共5页
A new synchronization technique of inner and outer couplings is proposed in this work to investigate the synchro- nization of network group. Some Haken-Lorenz lasers with chaos behaviors are taken as the nodes to cons... A new synchronization technique of inner and outer couplings is proposed in this work to investigate the synchro- nization of network group. Some Haken-Lorenz lasers with chaos behaviors are taken as the nodes to construct a few nearest neighbor complex networks and those sub-networks are also connected to form a network group. The effective node controllers are designed based on Lyapunov function and the complete synchronization among the sub-networks is realized perfectly under inner and outer couplings. The work is of potential applications in the cooperation output of lasers and the communication network. 展开更多
关键词 synchronization of network group inner and outer couplings Haken-Lorenz laser nearest neigh-bor network
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Coordinated chaos control of urban expressway based on synchronization of complex networks
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作者 Ming-bao Pang Yu-man Huang 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第11期672-682,共11页
We investigate the problem of coordinated chaos control on an urban expressway based on pinning synchronization of complex networks. A node coupling model of an urban expressway based on complex networks has been esta... We investigate the problem of coordinated chaos control on an urban expressway based on pinning synchronization of complex networks. A node coupling model of an urban expressway based on complex networks has been established using the cell transmission model(CTM). The pinning controller corresponding to multi-ramp coordinated controller was designed by using the delayed feedback control(DFC) method, whose objective is to realize periodical orbits from chaotic states. The concrete pinning control nodes corresponding to the subsystems of regulating the inflows from the on-ramps to the mainline were obtained and the parameters of the controller were optimized by using the stability theory of complex networks to ensure the network synchronization. The validity of the proposed coordinated chaos control method was proven via the simulation experiment. The results of the examples indicated that the order motion on urban expressway can be realized, the wide-moving traffic jam can be suppressed, and the operating efficiency is superior to that of the traditional control methods. 展开更多
关键词 pinning synchronization of complex networks multi-on-ramp metering of urban expressway chaos control delayed feedback control (DFC)
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Robust Synchronization in an E/I Network with Medium Synaptic Delay and High Level of Heterogeneity
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作者 韩芳 王直杰 +1 位作者 范宏 龚涛 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第4期25-28,共4页
It is known that both excitatory and inhibitory neuronal networks can achieve robust synchronization only under certain conditions, such as long synaptic delay or low level of heterogeneity. In this work, robust synch... It is known that both excitatory and inhibitory neuronal networks can achieve robust synchronization only under certain conditions, such as long synaptic delay or low level of heterogeneity. In this work, robust synchronization can be found in an excitatory/inhibitory (E/I) neuronal network with medium synaptie delay and high level of heterogeneity, which often occurs in real neuronal networks. Two effects of post-synaptic potentials (PSP) to network synchronization are presented, and the synaptic contribution of excitatory and inhibitory neurons to robust synchronization in this E/I network is investigated. It is found that both excitatory and inhibitory neurons may contribute to robust synchronization in E/I networks, especially the excitatory PSP has a more positive effect on synchronization in E/I networks than that in excitatory networks. This may explain the strong robustness of synchronization in Eli neuronal networks. 展开更多
关键词 PSP Robust synchronization in an E/I network with Medium Synaptic Delay and High Level of Heterogeneity
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QoS Adaptive Topology Configuration in Synchronous Wireless Sensor Networks 被引量:1
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作者 杨挺 武娇雯 +1 位作者 李昂 张志东 《Transactions of Tianjin University》 EI CAS 2010年第5期354-358,共5页
By using hyper-graph theory,this paper proposes a QoS adaptive topology configuration(QATC) algorithm to effectively control large-scale topology and achieve robust data transmitting in synchronous wireless sensor net... By using hyper-graph theory,this paper proposes a QoS adaptive topology configuration(QATC) algorithm to effectively control large-scale topology and achieve robust data transmitting in synchronous wireless sensor networks.Firstly,a concise hyper-graph model is abstracted to analyze the large-scale and high-connectivity network.Secondly,based on the control theory of biologic 'Cell Mergence',a novel self-adaptive topology configuration algorithm is used to build homologous perceptive data logic sub-network ... 展开更多
关键词 wireless sensor network QOS TOPOLOGY synchronous network
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Automatic Configuration in NTP
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作者 蒋宗礼 Xu Binbin 《High Technology Letters》 EI CAS 2003年第4期70-73,共4页
NTP is nowadays the most widely used distributed network time protocol, which aims at synchronizing the clocks of computers in a network and keeping the accuracy and validation of the time information which is transmi... NTP is nowadays the most widely used distributed network time protocol, which aims at synchronizing the clocks of computers in a network and keeping the accuracy and validation of the time information which is transmitted in the network. Without automatic configuration mechanism, the stability and flexibility of the synchronization network built upon NTP protocol are not satisfying. P2P’s resource discovery mechanism is used to look for time sources in a synchronization network, and according to the network environment and node’s quality, the synchronization network is constructed dynamically. 展开更多
关键词 synchronization network timekeeping automatic configuration NTP
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Time synchronization in communication networks based on the Beidou foundation enhancement system 被引量:7
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作者 LIU Hui ZHANG RuFei +1 位作者 LIU JingNan ZHANG Ming 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第1期9-15,共7页
Communication networks rely on time synchronization information generated by base station equipment(either the Global Navigation Satellite System receiver or rubidium atomic clock) to enable wireless networking and co... Communication networks rely on time synchronization information generated by base station equipment(either the Global Navigation Satellite System receiver or rubidium atomic clock) to enable wireless networking and communications. Meanwhile, the time synchronization among base stations depends on the Network Time Protocol. With the development of mobile communication systems, the corresponding time synchronization accuracy has increased as well. In this case, the use of sparsely distributed-high-precision synchronization points to synchronize time for an entire network with high precision is a key problem and is the foundation of the enhanced network communication. The current receiver equipment for China's digital synchronous network typically includes dedicated multi-channel GPS receivers for communication; however, with the development of GPS by the USA, network security has been destabilized and reliability is low. Nonetheless, network time synchronization based on Beidou satellite navigation system timing devices is an inevitable development trend for China's digital communications network with the establishment of the independently developed BDS, especially the implementation and improvement of the Beidou foundation enhancement system. 展开更多
关键词 Beidou satellite navigation system precision timing time synchronization Beidou foundation enhancement system communication network time synchronization
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Data-Driven Leader-Follower Output Synchronization for Networked Non-Linear Multi-Agent Systems with Switching Topology and Time-Varying Delays 被引量:7
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作者 LI Chang-Jiang LIU Guo-Ping 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2018年第1期87-102,共16页
This paper studies the output synchronization problem for a class of networked non-linear multi-agent systems with switching topology and time-varying delays. To synchronize the outputs,a leader is introduced whose co... This paper studies the output synchronization problem for a class of networked non-linear multi-agent systems with switching topology and time-varying delays. To synchronize the outputs,a leader is introduced whose connectivity to the followers varies with time, and a novel data-driven consensus protocol based on model free adaptive control is proposed, where the reference input of each follower is designed to be the time-varying average of the neighboring agents' outputs. Both the case when the leader is with a prescribed reference input and the case otherwise are considered.The proposed protocol allows for time-varying delays, switching topology, and does not use the agent structure or the dynamics information implicitly or explicitly. Sufficient conditions are derived to guarantee the closed-loop stability, and conditions for consensus convergence are obtained, where only a joint spanning tree is required. Numerical simulations and practical experiments are conducted to demonstrate the effectiveness of the proposed protocol. 展开更多
关键词 Data-driven networked nonlinear multi-agent system output synchronization switching topology time-varying delay
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Synchronization criteria for multiple memristor-based neural networks with time delay and inertial term 被引量:6
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作者 LI Ning CAO JinDe 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2018年第4期612-622,共11页
This present work uses different methods to synchronize the inertial memristor systems with linear coupling. Firstly, the mathematical model of inertial memristor-based neural networks(IMNNs) with time delay is propos... This present work uses different methods to synchronize the inertial memristor systems with linear coupling. Firstly, the mathematical model of inertial memristor-based neural networks(IMNNs) with time delay is proposed, where the coupling matrix satisfies the diffusion condition, which can be symmetric or asymmetric. Secondly, by using differential inclusion method and Halanay inequality, some algebraic self-synchronization criteria are obtained. Then, via constructing effective Lyapunov functional, designing discontinuous control algorithms, some new sufficient conditions are gained to achieve synchronization of networks. Finally, two illustrative simulations are provided to show the validity of the obtained results, which cannot be contained by each other. 展开更多
关键词 memristor-based neural networks(MNNs) inertial term synchronization discontinuous control
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SYNCHRONOUS LEARNING NETWORK:HOW COLLEGE STUDENTS USE PEER ASSESSMENT TECHNIQUES IN EVALUATION OF THEIR WRITING
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作者 翁克山 李青 《Chinese Journal of Applied Linguistics》 2009年第6期52-64,129,共14页
This study investigated how students used peer assessments in synchronous learning network (SLN) to assess each other s writing. It focused on examining the frequency and styles of various techniques students employed... This study investigated how students used peer assessments in synchronous learning network (SLN) to assess each other s writing. It focused on examining the frequency and styles of various techniques students employed while assessing each others writing and student response to assessing each other s writing in a SLN context. The findings indicated that these students received many assessments during each peer assessment activity. They preferred to use assessing techniques of less critical types, and had po... 展开更多
关键词 peer assessment synchronous learning network online writing community
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Improving the Syllable-Synchronous Network SearchAlgorithm for Word Decoding in ContinuousChinese Speech Recognition 被引量:2
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作者 郑方 武健 宋战江 《Journal of Computer Science & Technology》 SCIE EI CSCD 2000年第5期461-471,共11页
The previously proposed syllable-synchronous network search (SSNS) algorithm plays a very important role in the word decoding of the continuous Chinese speech recognition and achieves satisfying performance. Several r... The previously proposed syllable-synchronous network search (SSNS) algorithm plays a very important role in the word decoding of the continuous Chinese speech recognition and achieves satisfying performance. Several related key factors that may affect the overall word decoding effect are carefully studied in this paper, including the perfecting of the vocabulary, the big-discount Turing re-estimating of the N-Gram probabilities, and the managing of the searching path buffers. Based on these discussions, corresponding approaches to improving the SSNS algorithm are proposed. Compared with the previous version of SSNS algorithm, the new version decreases the Chinese character error rate (CCER) in the word decoding by 42.1% across a database consisting of a large number of testing sentences (syllable strings). 展开更多
关键词 large-vocabulary continuous Chinese speech recognition word decoding syllable- synchronous network search word segmentation
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A New Approach to Implement Synchronous Demultiplexers in High-Speed ISDN Switching Network
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作者 叶航军 刘斌 《Tsinghua Science and Technology》 SCIE EI CAS 2001年第1期10-13,共4页
This paper proves that a synchronous demultiplexer has the same logic function as a synchronous multiplexer. A new approach is proposed to implement synchronous demultiplexers in high-speed ISDN switching networks. A ... This paper proves that a synchronous demultiplexer has the same logic function as a synchronous multiplexer. A new approach is proposed to implement synchronous demultiplexers in high-speed ISDN switching networks. A synchronous demultiplexer is designed utilizing the same structure as a synchronous shuffle multiplexer. Both the theoretical analysis and experimental results show that for the same capacity, the new method is more tolerant of signal delay variation, so a very high-speed synchronous demultiplexer can be designed with the larger capacity required in large capacity synchronous switching networks. 展开更多
关键词 synchronous switching network (SSN) synchronous shuffle multiplexer synchronous demultiplexer
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Exponential stability of memristor-based synchronous switching neural networks with time delays
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作者 Yinlu Jiang Chuandong Li 《International Journal of Biomathematics》 2016年第1期301-318,共18页
In this paper, we study the existence, uniqueness and stability of memristor-based syn- chronous switching neural networks with time delays. Several criteria of exponential stability are given by introducing multiple ... In this paper, we study the existence, uniqueness and stability of memristor-based syn- chronous switching neural networks with time delays. Several criteria of exponential stability are given by introducing multiple Lyapunov functions. In comparison with the existing publications on simplice memristive neural networks or switching neural net- works, we consider a system with a series of switchings, these switchings are assumed to be synchronous with memristive switching mechanism. Moreover, the proposed stability conditions are straightforward and convenient and can reflect the impact of time delay on the stability. Two examples are also presented to illustrate the effectiveness of the theoretical results. 展开更多
关键词 Memristor-based synchronous switching neural networks exponential stabi-lity time delays Lyapunov functions.
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