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Pre-Bötzinger复合体是兴奋性耦合的神经元网络,通过产生复杂的放电节律和节律模式的同步转迁参与调控呼吸节律.本文选用复杂簇和峰放电节律的单神经元数学模型构建复合体模型,仿真了与生物学实验相关的多类同步节律模式及其复杂转迁历程,并利用快慢变量分离揭示了相应的分岔机制.当初值相同时,随着兴奋性耦合强度的增加,复合体模型依次表现出完全同步的“fold/homoclinic”,“subHopf/subHopf”簇放电和周期1峰放电.当初值不同时,随耦合强度增加,表现为由“fold/homoclinic”,到“fold/fold limit cycle”、到“subHopf/subHopf”与“fold/fold limit cycle”的混合簇放电、再到“subHopf/subHopf”簇放电的相位同步转迁,最后到反相同步周期1峰放电.完全(同相)同步和反相同步的周期1节律表现出了不同分岔机制.反相峰同步行为给出了与强兴奋性耦合容易诱发同相同步这一传统观念不同的新示例.研究结果给出了preBötzinger复合体的从簇到峰放电节律的同步转迁规律及复杂分岔机制,反常同步行为丰富了非线性动力学的内涵. 相似文献
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选用混沌自催化反应作为子系统 ,构造了耦合自催化反应系统 ,研究了耦合变量、耦合系数对混沌动力学行为的影响 ,给出了不同耦合系数下系统的动力学特征 ,探讨了耦合作用机制 .结果表明 ,耦合作用能明显地改变子系统的动力学行为 ,强化系统间的相关性 .耦合后的混沌运动受到调整与抑制 ,耦合强度加大时 ,呈现出混沌运动轨线的周期化 ,耦合系数大于临界值 ,两子系统实现了完全的同步 .不同变量的耦合时 ,影响最大的是第二种变量 .对于三种物质均有耦合时 ,更容易出现混沌的抑制、运动状态的锁相与周期化和混沌的完全同步 . 相似文献
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非线性动力学系统的混沌同步, 一般采用单向线性耦合的控制方式, 对于函数耦合方式研究的比较少. 这就存在一个问题, 对于非线性动力学系统, 在线性耦合实现混沌同步后, 是否其他函数的耦合方式都可以实现混沌同步? 本文对于一类非线性动力学系统, 研究了其线性耦合同步与函数耦合同步的关系, 证明当线性耦合实现同步后, 函数在满足一定的条件下, 可以通过函数耦合实现系统的混沌同步. 最后对于Duffing系统采用两种函数耦合进行了仿真计算, 证明了结论的正确性. 相似文献
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把量子阱激光混沌耦合反馈同步系统应用于光纤保密通信中,提出光纤混沌双芯双向保密通信设想.通过耦合外部光注入多量子阱激光混沌全光耦合反馈同步系统和光纤传输信道,建立了光纤混沌双芯双向通信系统物理模型.理论和数值证明了激光混沌同步,理论分析指出光纤中的自相位调制是限制激光混沌在光纤传输中同步的主要原因,并推导出混沌信号双芯双向传输中的非线性相移以及混沌激光功率限制和传输距离公式.数值实现了该系统在长距离二根光纤传输中的同步,详细地分析了系统同步时间随光纤传输长度的关系.模拟了调制频率06 GHz的混沌模拟通
关键词:
混沌
同步
光纤
保密通信 相似文献
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给出了一种可高质量传送数字信号的保密通信系统,该系统利用耦合同步洛伦兹混沌电路系统进行数字信号的混沌遮掩传送.模拟实验表明,传送信息保密性好,在接收端用同步的混沌信号将信息信号检出并整形后可无失真的恢复所传送的数字信号. 相似文献
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节律行为,即系统行为呈现随时间的周期变化,在我们的周围随处可见.不同节律之间可以通过相互影响、相互作用产生自组织,其中同步是最典型、最直接的有序行为,它也是非线性波、斑图、集群行为等的物理内在机制.不同的节律可以用具有不同频率的振子(极限环)来刻画,它们之间的同步可以用耦合极限环系统的动力学来加以研究.微观动力学表明,随着耦合强度增强,振子同步伴随着动力学状态空间降维到一个低维子空间,该空间由序参量来描述.序参量的涌现及其所描述的宏观动力学行为可借助于协同学与流形理论等降维思想来进行.本文从统计物理学的角度讨论了耦合振子系统序参量涌现的几种降维方案,并对它们进行了对比分析.序参量理论可有效应用于耦合振子系统的同步自组织与相变现象的分析,通过进一步研究序参量的动力学及其分岔行为,可以对复杂系统的涌现动力学有更为深刻的理解. 相似文献
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通过生物学实验研究了两个异质心肌细胞由独立到形成网络过程中的搏动节律随耦合强度的增加的动力学行为的变化.没有耦合时,两个细胞的搏动节律是独立的,没有同步的搏动.随着耦合强度的增加,网络内的两个细胞搏动节律的相位差的绝对值的平均值和最大值急剧降低,从非相位同步达到了相位同步,但没有达到完全同步.逐次对比两个细胞的搏动,非相位同步状态下只有部分搏动是同步的而其他搏动是不同步的,而相位同步状态下所有的搏动都是同步的.随着耦合强度的增加,非相位同步状态下的同步搏动次数增加,相位同步状态下的两细胞每次同步搏动的时间间隔降低但不为零.研究结果不仅给出了异质生物网络节律同步的实验例证,还获得了网络的节律从不同步到同步过程的动力学规律. 相似文献
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We have analyzed simultaneous recordings of respiration and heartbeat intervals in diabetic patients and control subjects. Our main findings are that in diabetic patients the heart beat-to-beat interval variability and cardiorespiratory crosscorrelation are decreased, the autocorrelation time of the interval series is increased, and the phase relation of the respiration with the heartbeat interval oscillations is often reversed in comparison with the control subjects. We have been able to reproduce the data using a biophysical model in which the time dependent input signal to the sinoatrial node was constituted of quasiperiodic and aperiodic components. The quasiperiodic input was obtained from the recording of the respiratory signal and the aperiodic input was obtained from selected realizations of correlated noise. Our study indicates that both input components to the sinoatrial node are modified in diabetic patients. 相似文献
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Scaling analysis of heartbeat time series has emerged as a useful tool for assessing the autonomic cardiac control under various physiologic and pathologic conditions. We study the heartbeat activity and scaling behavior of heartbeat fluctuations regulated by autonomic nervous system for professional shooting athletes under two states: rest and exercise, by applying the detrended fluctuation analysis method. We focus on alteration in correlation properties of heartbeat intervals for the shooters from rest to exercise, which may have a potential value in monitoring the quality of training and evaluating the sports capacity of the athletes. The result shows that scaling exponents of short-term heart rate variability signals from the shooters get significantly larger during exercise compared with those obtained at rest. It demonstrates that during exercise stronger correlations appear in the heartbeat series of shooting athletes in order to satisfy the specific requirements for high concentration and better control on their heart beats. 相似文献
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Ivanov PC Nunes Amaral LA Goldberger AL Havlin S Rosenblum MG Stanley HE Struzik ZR 《Chaos (Woodbury, N.Y.)》2001,11(3):641-652
We explore the degree to which concepts developed in statistical physics can be usefully applied to physiological signals. We illustrate the problems related to physiologic signal analysis with representative examples of human heartbeat dynamics under healthy and pathologic conditions. We first review recent progress based on two analysis methods, power spectrum and detrended fluctuation analysis, used to quantify long-range power-law correlations in noisy heartbeat fluctuations. The finding of power-law correlations indicates presence of scale-invariant, fractal structures in the human heartbeat. These fractal structures are represented by self-affine cascades of beat-to-beat fluctuations revealed by wavelet decomposition at different time scales. We then describe very recent work that quantifies multifractal features in these cascades, and the discovery that the multifractal structure of healthy dynamics is lost with congestive heart failure. The analytic tools we discuss may be used on a wide range of physiologic signals. (c) 2001 American Institute of Physics. 相似文献
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《中国物理快报》2016,(3)
We experimentally demonstrate the relation of Raman coupling strength with the external bias magnetic field in degenerate Fermi gas of ~(40)K atoms.Two Raman lasers couple two Zeeman energy levels,whose energy splitting depends on the external bias magnetic field.The Raman coupling strength is determined by measuring the Rabi oscillation frequency.The characteristics of the Rabi oscillation is to be damped after several periods due to Fermi atoms in different momentum states oscillating with different Rabi frequencies.The experimental results show that the Raman coupling strength will decrease as the external bias magnetic field increases,which is in good agreement with the theoretical prediction. 相似文献
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Peng C-K Mietus J Hausdorff JM Havlin S Stanley HE Goldberger AL 《Physical review letters》1993,70(9):1343-1346
We find that the successive increments in the cardiac beat-to-beat intervals of healthy subjects display scale-invariant, long-range anticorrelations (up to 10(4) heart beats). Furthermore, we find that the histogram for the heartbeat intervals increments is well described by a Lévy stable distribution. For a group of subjects with severe heart disease, we find that the distribution is unchanged, but the long-range correlations vanish. Therefore, the different scaling behavior in health and disease must relate to the underlying dynamics of the heartbeat. 相似文献
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Application of statistical physics to heartbeat diagnosis. 总被引:3,自引:0,他引:3
S Havlin L A Amaral Y Ashkenazy A L Goldberger C K Ivanov PChPeng H E Stanley 《Physica A》1999,274(1-2):99-110
We present several recent studies based on statistical physics concepts that can be used as diagnostic tools for heart failure. We describe the scaling exponent characterizing the long-range correlations in heartbeat time series as well as the multifractal features recently discovered in heartbeat rhythm. It is found that both features, the long-range correlations and the multifractility, are weaker in cases of heart failure. 相似文献
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We investigate the multifractality of heartbeat dynamics during Chinese CHI meditation in healthy young adults. The results show that the range of multifractal singularity spectrum of heartbeat interval time series during meditation is significantly narrower than those in the pre-meditation state of the same subject, which indicates that during meditation the heartbeat becomes regular and the degree of multifractality decreases. 相似文献
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Transitions in the dynamics of complex systems can be characterized by changes in the synchronization behavior of their components. Taking the human cardiorespiratory system as an example and using an automated procedure for screening the synchrograms of 112 healthy subjects we study the frequency and the distribution of synchronization episodes under different physiological conditions that occur during sleep. We find that phase synchronization between heartbeat and breathing is significantly enhanced during non-rapid-eye-movement (non-REM) sleep (deep sleep and light sleep) and reduced during REM sleep. Our results suggest that the synchronization is mainly due to a weak influence of the breathing oscillator upon the heartbeat oscillator, which is disturbed in the presence of long-term correlated noise, superimposed by the activity of higher brain regions during REM sleep. 相似文献