Gear fault detection using multi-scale morphological filters

This work gives a thorough exploration of the capacity of multi-scale morphological filters for gear fault detection. Eight types of multi-scale morphological filters are designed based on the mathematical morphology theory. A characteristic frequency intensity coefficient (CFIC) is defined as a quantity criterion for assessing the effectiveness of the filters. Both simulated signal and practical vibration signal measured from a gearbox are utilized to evaluate the fault detection ability of the eight multi-scale morphological filters. The conventional envelope analysis (EA) and another multi-scale analysis technique means the continuous wavelet transform combined with envelope analysis (CWT-EA) are also employed for a comparison. Experimental results have revealed that the averaged multi-scale morphological dilate-erode gradient (AMMG_DE) filter achieves the best performance for detecting gear defects. Furthermore, the computation cost of the AMMG_DE is comparable to the EA but much less than the CWT-EA technique. Therefore, the AMMG_DE filter is a very attractive technique for on-line condition monitoring of gear and other similar rotating machineries.     

Comparative study of frame-compatible stereo 3D services and a novel method for spatial interleaving using HEVC

There are a number of ways to realize frame-compatible stereo 3D services, which includes the spatial and temporal interleaving based methods. We first present the detailed analysis of these methods with respect to compression efficiency, backward compatibility and the ability to re-use existing infrastructure. Simulations have been set up to benchmark the Rate–Distortion (R–D) performance of these options with the state-of-the-art Multiview Video Coding (MVC) and results show that temporal interleaving based method performs better when compared to spatial interleaving in both H.264/AVC as well as in HEVC compression schemes, with MVC still outperforms both the methods. In the case of the spatial interleaving method using HEVC, we propose to encapsulate the two views in different tiles with filters turned off across the tile boundary. Simulation results show that the proposed method, when compared to “no-tiles” case, improves decoder performance by approximately 50% with no reduction in R–D performance.     

Scale aware remote sensing image enhancement using rolling guidance

Enhancement of remotely sensed images is a challenging problem, since the enhanced image has to have an improved contrast and edge information while preserving the original radiance values as much as possible. In this paper, a scale aware enhancement method based on rolling guidance is proposed for remotely sensed images. For each scale, a guidance image is defined and the approximation image is provided by an iterative joint filtering of the approximation and guidance images. Then the extracted details are amplified through an adaptive scheme and added to the final level approximation layer to provide the resulting enhanced image. A comparative study between the proposed methods with classical edge preserving filters and traditional methods have been carried out by using several criteria. The proposed methods have an average of 12% improvement for contrast gain (CG) metric and 81% improvement for enhancement measurement (EME) metric compared to the closest comparison method.     

Texture classification and discrimination for region-based image retrieval

In RBIR, texture features are crucial in determining the class a region belongs to since they can overcome the limitations of color and shape features. Two robust approaches to model texture features are Gabor and curvelet features. Although both features are close to human visual perception, sufficient information needs to be extracted from their sub-bands for effective texture classification. Moreover, shape irregularity can be a problem since Gabor and curvelet transforms can only be applied on the regular shapes. In this paper, we propose an approach that uses both the Gabor wavelet and the curvelet transforms on the transferred regular shapes of the image regions. We also apply a fitting method to encode the sub-bands’ information in the polynomial coefficients to create a texture feature vector with the maximum power of discrimination. Experiments on texture classification task with ImageCLEF and Outex databases demonstrate the effectiveness of the proposed approach.     

Particle filter based hybrid prognostics of proton exchange membrane fuel cell in bond graph framework

This paper presents a holistic solution towards prognostics of industrial Proton Exchange Membrane Fuel Cell. It involves an efficient multi-energetic model suited for diagnostics and prognostics, developed using some specific properties of Bond Graph (BG) theory. The benefits of Particle Filters (PF) are integrated with the BG model derived fault indicators named Analytical Redundancy Relations, for prognostics of the Electrical-Electrochemical part. The hybrid prognostics involves statistical degradation model obtained using real degradation tests. Prognostics problem is formulated as the joint state-parameter estimation problem in PF framework where estimations of state of health (SOH) is obtained in probabilistic domain. This in turn is used for prediction of Remaining Useful Life (RUL) under constant current as well as dynamic current solicitations. The SOH estimation and RUL prediction is obtained with very high accuracy and precise confidence bounds. Moreover, a comparative analysis with Extended Kalman Filter demonstrates the usefulness of PF.     

Optimal harmonic filters design of the Taiwan high speed rail traction system of distributer generation system with specially connected transformers

This paper presents a method for combining a particle swarm optimization with nonlinear time-varying evolution and orthogonal arrays (PSO-NTVEOA) in the planning of harmonic filters for the high speed railway traction system of Distributed Generation (DG) system with specially connected transformers in unbalanced three-phase power systems. The objective is to minimize the cost of the filter, the filters loss, the total harmonic distortion of currents and voltages at each bus simultaneously. An orthogonal array is first conducted to obtain the initial solution set. The set is then treated as the initial training sample. Next, the PSO-NTVEOA method parameters are determined by using matrix experiments with an orthogonal array, in which a minimal number of experiments would have an effect that approximates the full factorial experiments. This PSO-NTVEOA method is then applied to design optimal harmonic filters in Taiwan HSR traction system, where both rectifiers and inverters with IGBT are used. From the results of the illustrative examples, the feasibility of the PSO-NTVEOA to design an optimal passive harmonic filter of Taiwan HSR system is verified and the design approach can greatly reduce the harmonic distortion. Three design schemes are compared that V–V connection suppressing the 3rd order harmonic and Scott connection for the harmonic improvement is better than those of V–V and Le Blanc connection.     

Estimation of peak transient voltages at wind turbine generator terminals

This paper proposes equivalent circuits and a method for the estimation of the peak transient voltages at generator terminals in wind turbines equipped with back‐to‐back converters. Equivalent circuits as well as a way of phase‐to‐phase and phase‐to‐ground voltages estimation in back‐to‐back converter are presented. Proposed theoretical background is well confirmed by small‐scale measurements. It is shown and proven that phase‐to‐ground voltages represent a dominating threat for the wind turbine generators insulation. Copyright © 2014 John Wiley & Sons, Ltd.     

Defect detection with CCD-spectrometer and photodiode-based arc-welding monitoring systems

In this paper a detailed study on the ability of a system based on photodiodes to detect a wide variety of weld defects is presented. Narrow optical filters have been included within the setup to analyse their influence in the resulting monitoring signal and a direct comparison to the performance of the spectrometer has been also considered. The results obtained during the experimental tests indicate that the use of these filters clearly improves the resulting monitoring signals provided by the photodiodes, suggesting that a photodiode-based setup could become an alternative to the employment of spectrometers in some particular scenarios.     

A New Control Method of Suppressing the DC‐Capacitor Voltage Ripple Caused by Third‐Order Harmonic Compensation in Three‐Phase Active Power Filters

This paper proposes a new control method suitable for active power filters, which can reduce the dc capacitor voltage ripple associated with the third‐order harmonic current compensation. The proposed method superimposes a negative‐sequence fundamental current on the compensating current to cancel out the active power ripple caused by the third‐order harmonic current. As a result, the proposed method has the capability to eliminate the dc capacitor voltage ripple oscillating at double the source frequency. Experimental results obtained by a 10‐kW three‐phase diode rectifier load verify the validity of the proposed method. The proposed method exhibits a small dc capacitor voltage ripple reduced to 43% of that using the conventional method.     

Carbon Black based capacitive Fractional Order Element towards a new electronic device

In this paper, Fractional Order Elements (FOEs), fabricated by using a carbon black nano structured dielectrics, are presented. FOEs have been realized by varying different fabrication parameters such as the percentage of carbon black, the curing temperature, and the solvent type.Results on the experimental frequency characterization of one FOE device are given. The FOE has been, then, used for demonstrating the possibility of realizing a fractional order RC filter.The frequency analysis of the RC filter shows the coherence of the fractional order between the FOE and corresponding RC circuit.