The pressboard surface is the electric weak link of oil-paper insulation in transformers, and long-term partial discharge (PD) erosion dominant cause degradation pressboard. To explore development processes tracking under effect tip curvature, typical needle-plate model was selected to initiate an field with a high tangential component on needle curvature 4~42 μm. With help high-speed camera PD detecting system, were recorded sustained AC voltage. A profound difference between different...

This study explores the influence of hydrostatic pressure on discharge along oil-paper interface under AC voltage, especially for normal operating condition and breakdown. In this paper, an experimental platform was set up to record partial (PD) parameters test sample different pressures, while applied voltage increased final flashover step by step. Experimental results showed that higher had effects PD voltages. Higher decreased energy voltage. Furthermore, pressure, traces (white mark)...

The condition monitoring of the feedwater pump in secondary circuit is critical to safe operation nuclear power plant. This article presents a fault diagnosis method by using parameter-optimized support vector machine (SVM). While features are reflected from spectrum vibration signals, we trained and diagnosed feature table with machine. optimal penalty factor C kernel parameter γ selected grid search k-fold cross validation. Then faults SVM model under parameters. Diagnostic results show...

At present, most of the classification studies on EEG signals motor imagination focus left and right hands. In this paper, a feature analysis method based combination brain functional network common spatial pattern is proposed to solve dichotomy unilateral (right) hand imagination. Firstly, phase between Mu rhythm Beta carried out, then topology drawn according synchronization information matrix. Through analysis, MI - than more active, oscillation concentrated in center area C, FC CP. Then,...

The phenomena of white marks on the pressboard could reduce performance oil-paper composite insulation, which is accessed scrapped transformers. Whereas it much difficult to find during overhaul power ac transformer because mark channel generally disappear when connected air. So important a method detect pressboard. At first, throughout understanding development process should carry out under laboratory condition. A typical needle-plate electrodes model with was selected initiate divergent...

30CrMnSiNi2A steel is a high-strength low-alloy and it widely used in the defense industry. Its ductile fracture properties were investigated by using combined experimental-numerical approach to address need for assessment of structural integrity. The parameters Johnson-Cook constitutive model obtained through quasi-static dynamic tensile tests on round bar specimens at different temperatures relevant finite element method iterations. effects strain rate temperature studied. notched...

According to the non-stationary and non-linear characteristics of poultry voice situation that it`s hard obtain enough sound samples, a classification method based on Empirical Mode Decomposition (EMD), Teager energy transformation, Support Vector Machine (SVM) is proposed. Firstly, signals are decomposed into finite number intrinsic mode function (IMF).Then, five IMFs filtered used form characteristic vectors. Finally, eigenvectors put support vector machine classifier . The results animal...

This paper puts forward a classification method of imitating the human eyes to recognize image as whole which combined chaotic neural network and Empirical Mode Decomposition (EMD). The takes individual weeds plant research object utilizes network, EMD, Teager energy operator cluster analysis technology comprehensively. Firstly take two-dimensional gray matrix weight directly. Use with n neurons expression iterate get one-dimensional output curve. Secondly, make EMD decomposition for curve...

The interphase pressboard barriers sustain ac and dc composite voltage in the converter transformer, might degenerate after long terms' operation under voltage. typical needle-plane electrodes model was established laboratory condition. This paper researches partial discharge (PD) characteristics on oil-pressboard interface different DC polarities. surface change of caught by high-speed camera, PD were sampled commercial detector. results found PDs much higher negative polarity, energy...

To explore the effects of hand motion imagery on brain plasticity for use in guiding disabled people to robotic arms, this paper designed a comparison experiment between and normal people, collected EEG data 4 subjects (2 men who lost their right hands 2 men) five weeks training. What’s more, compared analyzed rhythm through topographic map. The results showed that after training, could produce ERD both μ β frequency bands, longer training time, more obvious phenomenon was. This also uses...

The paper analyzed the potential safety and stability control risk of southwest power grid, presented general online identification framework for operational risks second third defense line UHVDC sending-end elaborated key techniques realizing aforementioned functions, including security strategy/system protection strategy modelling, high frequency cutting generator modelling , conflict detection measures line, practicability assessment method strategy, other technologies. According to...