Learn More
Potential faults can be timely detected through online monitoring to the dissolved gases in the transformer oil so as to improve the safety of the electric power system. Firstly, the online monitoring technology of dissolved gases in the transformer oil is discussed in detail. Then, a low cost monitoring method to the characteristics gas dissolved in the(More)
During the Hilbert-Huang transformation (HHT), time-series data are firstly decomposed into several components with different time scale (i.e. intrinsic mode function, IMF), using the empirical mode decomposition (EMD). Then, the Hilbert transformation is applied to every IMF. As a result, the HHT spectrum of the data is constructed. In this paper, the(More)
Artificial intelligence (AI) techniques, which can effectively analyze massive amounts of fault data and automatically provide accurate diagnosis results, have been widely applied to fault diagnosis of rotating machinery. Conventional AI methods are applied using features selected by a human operator, which are manually extracted based on diagnostic(More)
This paper presents a novel type of tree-climbing robot. The main parts of the robot are 2 vehicles, which are attached on the trunk of a tree and were stick tightly on the tree because of a holding device. A kind of spine array is distributed on the wheels, and the friction is enhanced. Static stress analysis shows that the robot can overcome gravity and(More)
Unbalance, fatigue crack and rotor-stator rub are the three common and important faults in a rotor-bearing system. They are originally interconnected each other, and their vibration behaviors do often show strong nonlinear and transient characteristic, especially when more than one of them coexist in the system. This article is aimed to study the vibration(More)
The generation and propagation of surface acoustic waves (SAW) in an aluminum rod with variable cross-section subjected to laser beam illumination has been studied quantitatively by using the finite element method (FEM). The physical model of laser-induced SAW in the rod was built and the effects of the variable cross-section of the rod, the line source's(More)
Compound faults diagnosis is an important but difficult task in diagnostics. When several faults arise at the same time, vibration measurements by sensors show themselves as a complex integrated symptom, not as a simple and linear combination of several single faults, which makes it difficult to detect compound faults correctly. We proposed a new ICA-SOM(More)
As the optical penetration depth and thermal diffusion effect are small, shear waves and longitudinal waves generated by a laser pulse in thermoelastic regime are generally weak in metallic materials. The method of laser ultrasonic is rarely applied to inspect the inner cracks. In this paper, phased array laser ultrasonic is developed to focus and steer(More)
Thickness measurement is highly useful in industrials both for controlling the thickness of the product and for material characterization considering both mechanical and chemical properties. Longitudinal ultrasonic velocity can be used to measure material thickness provided that sufficient accuracy can be achieved. A new laser ultrasonic thickness(More)