Magnetic Anomaly Detection Based on a Compound Tri-Stable Stochastic Resonance System.

In the case of strong background noise, a tri-stable stochastic resonance model has higher noise utilization than a bi-stable stochastic resonance (BSR) model for weak signal detection. However, the problem of severe system parameter coupling in a conventional tri-stable stochastic resonance model leads to difficulty in potential function regulation. In this paper, a new compound tri-stable stochastic resonance (CTSR) model is proposed to address this problem by combining a Gaussian Potential model and the mixed bi-stable model. The weak magnetic anomaly signal detection system consists of the CTSR system and judgment system based on statistical analysis. The system parameters are adjusted by using a quantum genetic algorithm (QGA) to optimize the output signal-to-noise ratio (SNR). The experimental results show that the CTSR system performs better than the traditional tri-stable stochastic resonance (TTSR) system and BSR system. When the input SNR is -8 dB, the detection probability of the CTSR system approaches 80%. Moreover, this detection system not only detects the magnetic anomaly signal but also retains information on the relative motion (heading) of the ferromagnetic target and the magnetic detection device.

Study of a laser echo in an inhomogeneous dust environment with a continuous field Monte Carlo radiative transfer model.

A continuous field Monte Carlo radiative transfer model with an improved semianalytic approach is developed to study laser propagation in an inhomogeneous dust environment. In the proposed model, the photon step size can vary with the mass concentration of the dust environment. Additionally, the scattering properties of the dust particles are calculated with the T-matrix method and the T-matrix scattering phase function is applied to the Monte Carlo simulation with a rejection method. Using this model, the influences of the particle sizes and shapes on the backscattering properties are studied. Finally, the laser echoes simulated by our proposed model are compared with those of traditional Monte Carlo method and experimental results. Different mass concentration distributions indeed influence the simulated laser echo. The simulated results (of our proposed model) agree well with the measured data, demonstrating the effectiveness and accuracy of our approach for inhomogeneous media.