Inertial manifolds and forms for semilinear parabolic equations subjected to additive white noise

We present a construction of inertial manifolds and forms for semilinear parabolic equations subjected to additive white noise. The existence of inertial manifolds allow us to establish the existence of unique invariant distribution. We also derive the connection between this distribution and inertial forms of the system under consideration.     

Dirichlet forms and Markov semigroups onC*-algebras

We extend the classical theory of Dirichlet forms and associated Markov semigroups to the case of aC*-algebra with a trace. Semigroups of completely positive maps are characterized by completely positive Dirichlet forms.Work supported by The Norwegian Research Council for Science and the Humanities     

Entangled light from white noise

An atom that couples to two distinct leaky optical cavities is driven by an external optical white noise field. We describe how entanglement between the light fields sustained by two optical cavities arises in such a situation. The entanglement is maximized for intermediate values of the cavity damping rates and the intensity of the white noise field, vanishing both for small and for large values of these parameters and thus exhibiting a stochastic-resonancelike behavior. This example illustrates the possibility of generating entanglement by exclusively incoherent means and sheds new light on the constructive role noise may play in certain tasks of interest for quantum information processing.     

可编程多路白噪声发生器

伪随机噪声在数字信号处理中具有重要的实用价值,白噪声是产生具有指定概率分布的伪随机噪声的基础.本文给出一种数字式可编程多路白噪声发生器的原理设计,把传统的移位寄存器技术用高速静态RAM代替,可以同时产生多路相互独立的白噪声.用DSP编程,软件简单,硬件紧凑.系统仿真表明,用本设计所产生的白噪声统计特性好、性能稳定,完全能满足声呐和通信等有关领域的要求,本文给出了原理分析、设计框图,计算机仿真的结果。     

Consonant confusions in white noise

The classic [MN55] confusion matrix experiment (16 consonants, white noise masker) was repeated by using computerized procedures, similar to those of Phatak and Allen (2007). ["Consonant and vowel confusions in speech-weighted noise," J. Acoust. Soc. Am. 121, 2312-2316]. The consonant scores in white noise can be categorized in three sets: low-error set [/m/, /n/], average-error set [/p/, /t/, /k/, /s/, /[please see text]/, /d/, /g/, /z/, /Z/], and high-error set /f/theta/b/, /v/, /E/,/theta/]. The consonant confusions match those from MN55, except for the highly asymmetric voicing confusions of fricatives, biased in favor of voiced consonants. Masking noise cannot only reduce the recognition of a consonant, but also perceptually morph it into another consonant. There is a significant and systematic variability in the scores and confusion patterns of different utterances of the same consonant, which can be characterized as (a) confusion heterogeneity, where the competitors in the confusion groups of a consonant vary, and (b) threshold variability, where confusion threshold [i.e., signal-to-noise ratio (SNR) and score at which the confusion group is formed] varies. The average consonant error and errors for most of the individual consonants and consonant sets can be approximated as exponential functions of the articulation index (AI). An AI that is based on the peak-to-rms ratios of speech can explain the SNR differences across experiments.     

On the relation between white shot noise,Gaussian white noise,and the dichotomic Markov process

It is shown that the dichotomic Markov process converges to a white shot noise (interpreted according to the Stratonovich integration rule) in the joint limit in which the average duration of one of the states goes to zero and the value at this state goes to infinity. A further limit procedure allows us to obtain Gaussian white noise from white shot noise. These results are applied to the problem of noise-induced transitions. It is shown that white shot noise can give rise to transitions which do not occur for Gaussian white noise. The above results are finally generalized in introducing compound dichotomic Markov processes.     

Acoustic vibration of the amphibian eardrum studied by white noise analysis and holographic interferometry

The motion of the amphibian eardrum under free-field acoustic stimulation was investigated using time-averaged holography. We show that the amplitude is linearly related to sound pressure up to +/- 1000 nm. The frequency response of the eardrum shows broad resonance characteristics with a main peak between 1200-2200 Hz. The velocity of the tympanic membrane's motion at its resonance frequency matches the acoustic velocity of air particles. The resonance characteristics of the eardrum are also revealed by white noise stimulation. The power spectrum obtained by Fourier transformation of the autocorrelation of the response to noise resembles closely that obtained by holography.     

Stochastic (white noise) analysis of resonant absorption in laser generated plasma

We suggest to use stochastic differential equations for laser-plasma problems. Using this technique we solve analytically the motion of the electrons at the critical layer and calculate the density profile scaling length (L). For an Nd laser flux of 10¹⁷ W/cm² we estimate L ≈ 0.15 μm, while for a CO₂ laser flux of 10¹⁵ W/cm² we get L ≈ 1.5 μm.     

Steady-state analysis subject to a coloured and a white additive of a bistable system multiplicative noise noise with coloured cross-correlated noises

The steady-state properties of a bistable system are investigated when both the multiplicative noise and the coupling between additive and multiplicative noises are coloured with different values of noise correlation times T1 and T2. After introducing a dimensionless parameter R（R = α/D, D is the intensity of the multiplicative noise and a is the intensity of the additive noise）, and performing the numerical computations, we find the following points： （1） For the case of R 〉 1, A （the intensity of correlation between additive and multiplicative noises）, T1 and T2 can induce the stationary probability distribution （SPD） transition from bimodal to unimodal in structure, but for the cases of R _〈 1, the bimodal structure is preserved; （2） a can also induce the SPD transition from bimodal to unimodal in structure; （3） the bimodal structure of the SPD exhibits a symmetrical structure as D increases.     

On the interpretation of multiplicative white noise

The interpretation of a stochastic differential equation as an approximation to a stochastic difference equation is discussed. A criterion is presented for determining which stochastic calculus should be used.     

Chaotic time series prediction and additive white Gaussian noise

Taken's delay embedding theorem states that a pseudo state-space can be reconstructed from a time series consisting of observations of a chaotic process. However, experimental observations are inevitably corrupted by measurement noise, which can be modelled as Additive White Gaussian Noise (AWGN). This Letter analyses time series prediction in the presence of AWGN using the triangle inequality and the mean of the Nakagami distribution. It is shown that using more delay coordinates than those used by a typical delay embedding can improve prediction accuracy, when the mean magnitude of the input vector dominates the mean magnitude of AWGN.     

Stochastic resonance in a stochastic bistable system subject to additive white noise and dichotomous noise

The stochastic resonance (SR) in a stochastic stable system driven by a static force and a periodic square-wave signal as well as by additive white noise and dichotomous noise is considered from the point of view of the signal-to-noise ratio (SNR). It is found that the SNR exhibits SR behavior when it is plotted as a function of the noise strength of the white noise and dichotomous noise, as well as when plotted as a function of the static force. Moreover, the influence of the strength of the stochastic potential force and the correlation rate of the dichotomous noise is investigated.     

Multiplicative non-Gaussian noise and additive Gaussian white noise induced transition in a piecewise nonlinear model

We study the transition problems in a piecewise nonlinear model induced by correlated multiplicative non-Gaussian noise and additive Gaussian white noise. Firstly, applying the path integral approach, the unified colored noise approximation, the analytical expression of the steady-state probability density function (SPD) is derived. Then the change regulation of the SPD is analyzed with the change of the strength and relevance of multiplicative noise and additive noise. From numerical computations we obtain some new nonlinear phenomena: the transition can be induced by the cross-correlation strength between noises, the non-Gaussian noise intensity and the Gaussian noise intensity as well as the non-Gaussian noise deviation parameter. This indicates that the effect of the non-Gaussian noise intensity on SPD is the same as that of the Gaussian noise intensity. Moreover, we also find the correlation time of the non-Gaussian noise can not induce the transition.     

Choice of Japanese modifiers in noise annoyance scale during exposures to white noise

The linearity of a Japanese verbal scale of annoyance was estimated under real noise exposure. Young healthy adults, 32 male and 132 female were exposed to white noise of 30, 45, 60, 75 and 90 dBA in rooms where the exposure levels could be controlled according to contours. The series of noise exposure consisted of three components; white noise, pure-tone for conditioning and silence for evaluating noise. During the exposures the noisiness of each emission was evaluated with the verbal scale and a line-rating scale. The data showed a significant correlation of about 0.9 between the exposure level and the line length on the rating scale. The regression line of the noise level to the line length exhibited a reasonable locus of zero on the line length at the ambient noise level. The rank correlation between the selected modifier and the noise level was nearly 0.8 . When the five modifiers were converted to 1-5 points, respectively, the regression of the line length to the selected modifier revealed an adequate and consistent fitness (coefficient of determination was >0.8). The results suggest that the scale can be used as an equally divided linear scale in community noise research.     

一种增强带噪语音可懂度的新算法

一般的语音增强算法在强噪声环境中只能提高信噪比,不能提高可懂度。本文提出用可调节白噪声代替信号中非语音部分的语音可懂度增强处理新算法。实验证明此方法能明显改善强噪声时的语音可懂度,能对低至-10dB的带噪语音信号进行有效的可懂度增强。     

Preparation of bell states with controlled white noise

We report two methods for producing Bell States with an arbitrary amount of white noise. White noise in this context refers to controlled admixtures of unpolarized light. Our methods differ from previous experiments in that we use the minimum necessary elements for generating a Bell state by c-w spontaneous parametric down conversion. We also investigated the spectral properties of a mixed state and show that one of our methods introduces irreversible noise into the Bell state, making a permanent mixed state.     

Synchronization of self-sustained oscillators by common white noise

We study the stability of self-sustained oscillations under the influence of external noise. For small-noise amplitude a phase approximation for the Langevin dynamics is valid. A stationary distribution of the phase is used for an analytic calculation of the maximal Lyapunov exponent. We demonstrate that for small noise the exponent is negative, which corresponds to synchronization of oscillators.