Rail Roughness Acceptance Criterion Based on Metro Interior Noise

Severe rail roughness leads to a series of problems in metro systems,particularly the vehicle noise problem.To ensure a better acoustic environment,rail roughness control is therefore one of the main concerns for the metro operators.But the existing roughness acceptance criteria are not suitable for metro interior noise control.It is an appropriate method to determine the rail roughness limit based on interior noise.A rail roughness acceptance criterion based on metro interior noise is accordingly proposed in this paper.The relationship between rail roughness and interior noise can be derived with wheel-rail noise as link.With this objective,a combined test and simulation method is adopted.A validated wheel-rfigil noise prediction model is thus established to determine the relationship between rail roughness and wheel-rail noise.Moreover,the transfer function of wheel-rail noise to interior noise is developed based on extensive field test.Using this method,the noise sensitivity to roughness wavelength and acceptance criteria at different speeds and track structures are investigated.Finally,an eclectic rail corrugation acceptance criterion on curved track is suggested in consideration of practical application.

Pervasive underwater passive target tracking for the computation of standard deviation solution in a 3D environment

Purpose-Nowadays advancement in acoustic technology can be explored with marine assets.The purpose of the paper is pervasive computing underwater target tracking has aroused military and civilian interest as a key component of ocean exploration.While many pervasive techniques are currently found in the literature,there is little published research on the effectiveness of these paradigms in the target tracking context.Design/methodology/approach-The unscented Kalman filter(UKF)provides good results for bearing and elevation angles only tracking.Detailed methodology and mathematical modeling are carried out and used to analyze the performance of the filter based on the Monte Carlo simulation.Findings-Due to the intricacy of maritime surroundings,tracking underwater targets using acoustic signals,without knowing the range parameter is difficult.The intention is to find out the solution in terms of standard deviation in a three-dimensional(3D)space.Originality/value-A new method is found for the acceptance criteria for range,course,speed and pitch based on the standard deviation for bearing and elevation 3D target tracking using the unscented Kalman filter covariance matrix.In the Monte Carlo simulation,several scenarios are used and the results are shown.