[Application of Kohonen and BP neural networks to simultaneous determination of tungsten and molybdenum].

BP artificial neural networks combined with Kohonen networks were used for the simultaneous determination of tungsten and molybdenum by spectrophotometry. First, the topology structure of Kohonen artificial neural networks was studied, and applied to the wavelength selection of the overlapped spectra of tungsten and molybdenum. Then the most informative wavelengths were selected from the full spectra, and absorbance values were used as the optimal input sets of the three-layer BP neural networks.

Phenomenon of stochastic resonance caused by multiplicative asymmetric dichotomous noise.

The exact expression of the first moment and the signal-to-noise ratio (SNR) have been calculated for a linear system subject to an external periodic field as well as a multiplicative asymmetric dichotomous noise, by using the Shapiro-Loginov formula. It has been found that the amplitude of the output signal, and the SNR, respectively, exhibit two kinds of the phenomena of stochastic resonance: one is as the functions of the parameters of the asymmetric dichotomous noise, such as the noise strength D, and the parameter k describing the asymmetric degree of the dichotomous noise; the other is as the function of the parameter of the input signal, such as the input signal frequency omega.

Escape over a fluctuating potential barrier with three-state Markovian noise.

We consider the escape over a fluctuating potential barrier with a three-state Markovian noise. The resonant activations (RA's) for the mean first-passage times as functions of the transition rates gamma(1), gamma(2), and gamma(3) of the three-state Markovian noise are obtained, respectively. The effect of the three values of the three-state Markovian noise on the RA's is investigated.

Chaotic noisy transport of electron pairs in a superconducting junction device: thermal-inertia ratchets.

Chaotic noisy transport of electron pairs in a superconducting junction device (thermal-inertia ratchets) is investigated. The study shows that when the temperature is low enough, the transport of the electron pairs can be mainly chaotic; when the temperature is high enough, it can be mainly stochastic. By controlling the temperature and the amplitude of the input ac signal, the current of electron pairs can be reversed.

Superconducting junctions perturbed by environmental fluctuation.

A superconducting junctions device is investigated in the case of the environmental perturbation. It is found that a net voltage can be produced, whose absolute value represents a phenomenon of resonance versus the additive noise strength, and may be negative, positive, and zero. By controlling the correlation between the additive and multiplicative noises, a reversal for the net voltage can be induced.

System with temporal-spatial noise.

This paper investigates systems driven by temporal-spatial noise using two models, i.e., a spatially periodic model, and a model with infinite globally coupled oscillators.

Transitions and transport for a spatially periodic stochastic system with locally coupled oscillators.

In this paper, with a special model, we investigate the spatially periodic stochastic system with locally coupled oscillators subject to a constant force F. A nonequilibrium second-order phase transition is found when F=0. This phase transition is reentrant when the additive noise is weak.

Effect of asymmetry on stochastic resonance and stochastic resonance induced by multiplicative noise and by mean-field coupling.

In the paper, we investigate the effect of asymmetry of the potential on stochastic resonance (SR) for a model with an asymmetric bistable potential and driven by additive noise, the signal-to-noise ratio (SNR) for a model with a monostable potential and driven by additive and multiplicative noises, and the SNR for a mean-field coupled model with infinite globally coupling oscillators driven by additive noises. It is shown that for the first model,the asymmetry of the potential can weaken the phenomenon of SR; for the second and third models, a SR induced by multiplicative noise and a different one caused by mean-field coupling are found.