噪声信号与速度测量

利用两个敏感元件，对周围环境中的“景物”产生两列噪声信号，这两列信号间具有时间差，该时间差惟一地由相对运动的速度决定，计算出这个时间差就知道了速度值，实验样机在50km/h速度时，分辨率为1km/h。     

具有周期信号调制噪声的线性模型的随机共振

研究了具有周期信号调制噪声的过阻尼线性系统的随机共振现象.当采用非对称的分段噪声 时，可以得到系统响应的一、二阶矩和信噪比的精确表达式.通过对信噪比的分析, 发现了 “真实的"随机共振和传统的随机共振现象，讨论了乘性噪声的非对称性、自相关时间和噪 声之间的相关强度对信噪比的影响. 关键词： 随机共振 信噪比 周期信号调制噪声 线性模型     

含关联噪声与时滞项的非对称双稳系统的随机共振

研究了基于关联噪声的带时滞项的非对称双稳系统的随机共振，在小时滞量及绝热近似理论下得到了信噪比的精确解析表达式，表明由于时滞量的存在系统出现了随机共振.讨论了系统的时滞量、噪声相关系数及系统的非对称性对系统的信噪比的影响.     

输入信号和噪声对单模激光随机共振的影响

采用色抽运噪声和实虚部间关联的量子噪声驱动的单模激光损失模型,运用线性化近似方法计算了周期性信号加性输入时激光系统的输出光强信噪比,发现用信噪比与量子噪声实虚部间关联系数的关系曲线描述的随机共振现象.在抽运噪声自关联为短时关联情况下,当信号振幅增大和频率增快、抽运噪声色关联时间增大时,系统的随机共振加强;而噪声强度的增加会削弱系统的随机共振.在抽运噪声自关联为长时关联情况下,当信号振幅增大和量子噪声强度减弱时,系统的随机共振加强;而信号频率、抽运噪声强度、抽运噪声色关联时间的变化对系统随机共振的影响很小.     

噪声下时滞复杂网络的局部自适应H无穷一致性

针对具有噪声的一般时滞复杂动力网络, 研究了它的局部自适应H无穷一致性问题, 其中网络包含未知但有界的非线性耦合函数、节点和耦合项都具有时变时滞. 基于李雅谱诺夫稳定性理论, 线性矩阵不等式优化技术以及自适应控制方法, 提出了局部自适应H无穷一致充分条件, 这些条件不仅可以保证受噪声扰动的网络获得鲁棒渐近一致, 而且可以让网络达到一个给定的鲁棒H无穷水平. 数值模拟验证了所提出的方法的可行性和有效性. 关键词： H无穷一致 时滞复杂网络 噪声 线性矩阵不等式     

太赫兹微弱信号检测系统噪声处理方法研究

为了能够量化物体太赫兹辐射的大小,对黑体辐射中的太赫兹信号进行测量,使测量系统处于真空状态下,并且使用液氮制冷来屏蔽外界杂散辐射。黑体辐射的太赫兹信号由卡塞格林系统聚焦于探测器上。探测器的输出信号用锁相放大器进一步处理,并观察不同时间常数下锁相放大器的输出信号。实验结果表明:当黑体温度为323 k时,实验装置使用液氮制冷前后的测量结果有所不同,前后相差约3 v左右。时间常数对输出结果影响也很大,实验使用3 s比较合适。由于噪声来源复杂、噪声水平很高,黑体在太赫兹波段辐射能量极为微弱,所以系统对温度分辨率要求不是很高。     

红外测温中检测强噪声下微弱信号的新途径

就“BHJ 400”型便携式电脑红外测温仪的研制从理论和实践角度介绍了以下内容：①提高 红外光学系统信噪比的方法和途径;②提高红外探测器输出信号的方法和途径;③在探测器 输出信号处理电路中滤除广白噪声、有效提取并放大深埋在强噪声中微弱目标信号的方法和 途径.从而使该红外测温仪性能得到了最大限度地提高,实验结果和理论分析值相符,达到 了设计要求. 关键词：     

噪声信号特征量分布函数相似特性的研究

应用高速数据采集卡,记录悬浮颗粒计数光电传感器本底噪声信号序列值,研究噪声信号独立特征量, 如信号幅度极值、上升沿幅值、下降沿幅值、极值时序间隔,以及特征量乘积值等统计分布规律. 结果表明,上述独立特征量均能够与以自然数l为自变量的对数正态分布函数高度符合, 噪声信号特征量统计分布呈现出高度相似特征.基于这种统计相似性,还可推出噪声信号不同特征量对应的统计自变量之间的幂函数变换关系.噪声信号特征量统计分布函数相似性可理解为噪声信号集合统计分形特性的一种表现.     

互联网时滞对偶拥塞控制模型动力学特征的分析与计算

以互联网拥塞控制的一种时滞对偶改进模型为研究对象,应用标准形理论、中心流形定理和霍普夫分岔理论,从动力学角度研究互联网拥塞控制的分岔与稳定性分析方法.研究表明,模型的分岔与稳定性主要由通信时延决定,当通信时延超过临界值时模型产生分岔现象,使互联网的链路代价函数发生振荡.并得到该模型的分岔方向及分岔周期解等动力学特征的定量计算公式,为时滞对偶模型的设计提供理论依据.研究结论概括为两个定理,其正确性得到计算机仿真验证.     

水下噪声及信号的遥测浮标

本遥测浮标设计的主要特点在于采用了数字自动增益控制技术,还用了模拟-频移键控混合的信号传输方式(DAGC/FSK/PM.),以保证得到大动态范围压缩,保持水声信号波形的线性输出.同时,由浮标内设FSK标准信号对传输信号作绝对校准,直接测得声压绝对级. 浮标具有多种遥测水下信号的功能,可测海洋环境噪声、舰船辐射噪声,水下连续声波以及爆炸声源等形式的信号,并兼作水声-无线电应答测距.经多次在内陆水库、北海、东海、南海海上测试,效果良好.证明是一种海上测量的适用且经济的设备.     

Influences of noise correlation and time delay on stochastic resonance induced by multiplicative signal in a cancer growth system

This paper investigates the stochastic resonance (SR) phenomenon induced by the multiplicative periodic signal in a cancer growth system with the cross-correlated noises and time delay. To describe the periodic change of the birth rate due to the periodic treatment, a multiplicative periodic signal is added to the system. Under the condition of small delay time, the analytical expression of the signal-to-noise ratio R_{\rm SNR} is derived in the adiabatic limit. By numerical calculation, the effects of the cross-correlation strength \lambda and the delay time \tau on R_{\rm SNR} are respectively discussed. The existence of a peak in the curves of R_{\rm SNR} as a function of the noise intensities indicates the occurrence of the SR phenomenon. It is found that \lambda and \tau play opposite role on the SR phenomenon, i.e., the SR is suppressed by increasing \lambda whereas it is enhanced with the increase of \tau, which is different from the case where the periodic signal is additive.     

Effects of time delay and non-Gaussian noise on the dynamics of a perceptual bistability

In this paper, we investigate the effects of time delay and non-Gaussian noise on the dynamics properties of the attractor network model of perceptual bistability. Using delay Fokker–Planck equation and projection operator method, the stationary probability distribution P_st(x), the associated relaxation time T_c, and the normalized correlation function C(s) for perceptual bistability are obtained, respectively. Research results show that: (i) the time delay τ and the correlation time τ₀ from non-Gaussian noise can induce the change of the peaks in the P_st(x), i.e., the transition of the system appears; (ii) there exhibits an optimal value of the τ₀ or τ by which the T_c or C(s) is maximum, this maximum shows the τ₀ or τ first reduces the stability of the attractor network model of perceptual bistability in the steady state, and then enhances it; and (iii) the noise intensity P or departure q from the Gaussian noise only enhances the stability of the attractor network model of perceptual bistability in the steady state.     

Effects of colored noise and noise delay on a calcium oscillation system

As a calcium oscillations system is in steady state, the effects of colored noise and noise delay on the system is investigated using stochastic simulation methods. The results indicate that: (1) the colored noise can induce coherence bi-resonance phenomenon. (2) there exist three peaks in the R–_τ0$R\text{–}{\tau }_0$ (R$R$ is the reciprocal coefficient of variance, and _τ0${\tau }_0$ is the self-correlation time of the colored noise) curves. For the same noise intensity Q=1$Q=1$, the Gaussian colored noise can induce calcium spikes but the white noise cannot do this. (3) the delay time can improve noise induced spikes regularity as _τ0${\tau }_0$ is small, and R$R$ has a significant minimum with increasing τ$\tau$ as _τ0${\tau }_0$ is large. (4) large values of ζ$\zeta$ reduce noise induced spikes regularity.     

偏置信号调制下噪声关联的周期调制对单模激光随机共振的影响

在噪声受偏置信号调制的情况下,讨论色噪声之间的关联受时间周期调制所驱动的单模激光系统中的随机共振.用线性化近似的方法计算了输出信噪比.具体讨论输出信噪比随噪声自关联时间、噪声强度和偏置信号的变化关系.发现输出信噪比随抽运噪声强度和自关联时间的变化出现随机共振,而偏置信号会降低随机共振的峰值.实际应用中应控制优选偏置信号强度. 关键词： 偏置信号 色噪声 时间周期调制 噪声间关联程度     

TRC路径特征及其对时间反演信噪比的影响

时间反演具有时空聚焦特征,在许多方面有着潜在的应用。其中,基于时间反演腔的系统是一种主要的反演系统,可用于脉冲压缩、波束成形、微扰探测等。时间反演腔通常是一个电大的微波混沌腔,内部电磁波的传播具有明显的多径特征,即时间色散特征。因此,在时间反演过程中,反演腔可对反演信号进行相位补偿,重构出初始信号,从而在初始位置形成脉冲的时间压缩和空间聚焦。为了拓展时间反演腔的实际应用,本文基于多径信道模型研究腔体参数对反演性能的影响,重点分析路径的衰减特征、串扰特征和叠加特征对反演信噪比的影响,并总结给出影响反演信噪比的主要参数以及基本规律。     

时间延迟对基因调节回路中生物记忆影响研究

生物记忆是广泛存在于各种生物子系统的一种重要的效应. 基于一个双反馈的基因调节回路模型, 采用数值模拟的方法研究了局部反馈中存在的时间延迟对生物记忆时间的影响. 结果发现, 小量的延迟能够很大地提高生物记忆时间. 并且, 生物记忆随延迟时间呈线性增加. 这种增强模式与噪声对生物记忆时间的提高完全不同. 延迟和噪声对生物记忆的提高可以进行相互的控制增强, 但不会影响对方的增强模式.     

Modeling and dynamics of double Hindmarsh-Rose neuron with memristor-based magnetic coupling and time delay

The firing of a neuron model is mainly affected by the following factors:the magnetic field, external forcing current, time delay, etc. In this paper, a new time-delayed electromagnetic field coupled dual Hindmarsh-Rose neuron network model is constructed. A magnetically controlled threshold memristor is improved to represent the self-connected and the coupled magnetic fields triggered by the dynamic change of neuronal membrane potential for the adjacent neurons. Numerical simulation confirms that the coupled magnetic field can activate resting neurons to generate rich firing patterns, such as spiking firings, bursting firings, and chaotic firings, and enable neurons to generate larger firing amplitudes. The study also found that the strength of magnetic coupling in the neural network also affects the number of peaks in the discharge of bursting firing. Based on the existing medical treatment background of mental illness, the effects of time lag in the coupling process against neuron firing are studied. The results confirm that the neurons can respond well to external stimuli and coupled magnetic field with appropriate time delay, and keep periodic firing under a wide range of external forcing current.     

Intrinsic noise analysis and stochastic simulation on transforming growth factor beta signal pathway

A typical biological cell lives in a small volume at room temperature; the noise effect on the cell signal transduction pathway may play an important role in its dynamics. Here, using the transforming growth factor-β signal transduction pathway as an example, we report our stochastic simulations of the dynamics of the pathway and introduce a linear noise approximation method to calculate the transient intrinsic noise of pathway components. We compare the numerical solutions of the linear noise approximation with the statistic results of chemical Langevin equations, and find that they are quantitatively in agreement with the other. When transforming growth factor-β dose decreases to a low level, the time evolution of noise fluctuation of nuclear Smad2-Smad4 complex indicates the abnormal enhancement in the transient signal activation process.     

Effect of time delay on the upper bound of the time derivative of information entropy in a stochastic dynamical system

The effects of the time delay on the upper bound of the time derivative of information entropy are investigated in a time-delayed dynamical system driven by correlated noise. Using the Markov approximation of the stochastic delay differential equations and the Schwartz inequality principle, we obtain an analytical expression for the upper bound U_B(t) of the time derivative of the information entropy. The results show that there is a critical value of τ (delay time), and U_B(t) presents opposite behaviours on difference sides of the critical value. For the case of the weak additive noise, τ can induce a reentrance transition. Delay time τ also causes a reversal behaviour in U_B(t)-λ plot, where λ denotes the degree of the correlation between the two noises.     

利用随机共振在强噪声下提取信息信号

已有利用随机共振在强噪声下提取单一频率信号的若干报道，但单一频率信号所携带的信息量为零.本实验研究表明：在调幅波和白噪声的协同作用下，非线性双稳系统的输出不仅可以呈现随机共振现象，而且经检波、滤波后能提取出调制信号(信息信号)；与直接经电子学系统检波、线性滤波后所提取的调制信号相比，前者所获调制信号的信噪比更高.给出了绝热近似条件下，调制信号信噪比的解析表达式. 关键词： 随机共振 信噪比 调制信号 噪声