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The shaking table model test mainly focuses on the study of seismic response law, aseismic performance and seismic damping and isolation effect of bridges with a single or multi-platform shaking table. Basically, the plane principal axis direction is adopted for the seismic input of structural models. Little research effort considering multi-angle seismic input has been reported in the structural model test. In this paper we designed and conducted a small-scale shaking table model test to study the seismic response law of the curved girder bridges with seismic input at different angles, and provided experimental verification for the theoretical method of the most unfavorable angle of seismic input. The experimental results show that the variation trend of component response to variation of the seismic input direction is consistent with that of the numerical analysis, which indicates that the designed device is effective.

The damage detection of the wind turbine (WT) blade is an important aspect of its health situation monitoring. In order to catch small damages, it is necessary to stitch the multi segment images of the blade to obtain a high resolution image. In image stitching, a blurring of the image is carried out to reduce the influence of noise. However, the preprocessing may decrease the amount of feature points and cannot avoid the interaction of feature points in the background and the target parts. To overcome these problems, a preprocessing method based on background removal is proposed. The idea of the method is to carry out image segmentation to get the background part, then the intensities of pixels in background part are replaced by a same value, such as average intensity. Employing the proposed preprocessing method, the image stitching is implemented on several groups of WT blade images. Feature points extraction result are compared between the proposed and the blurring preprocessing, which shows that the proposed method is more robust to the parameters in image stitching process. Moreover, the capability about image stitching and multi-image stitching of the proposed method is well verified by the experiment results.

Wind energy, as a renewable energy source, has attracted great attention of many countries. It is converted into electricity by the important machine, wind turbine (WT). With the fast growing of WT capacity in the world, the costs of monitoring and maintaining increase year by year. One necessary part of these costs is for blades health situation monitoring, which directly affects effectiveness and safety of WT. Thus, the damage detection of the blades is of great significance. The blades suffer from sunshine, acid rain, sand attack, and others, which may cause kinds of damages, such as skin abscission, surface crack, and sand hole. Aiming at surface damage detection of the blades, the paper proposed a method based on variational image segmentation model. At beginning, an idea that objects in an image are left along with detection of the background part is present, and it is changed into an optimization problem by using the level set method and 1-D Heaviside function. Then the corresponding gradient descent minimization algorithm is derived. In the experimental part, a large number of blade images with surface damages are tested by applying the proposed method, and damages are all detected successfully. Moreover, the segmentation results of the noise images show that our method is robust to noise. This paper can provide effective technical support for surface damage detection of WT blades in-service.

The rapid and accurate detection of partial discharge (PD) in AC metal enclosed switchgear (switchgear cabinet) is of great significance to ensure the safe operation of power grid and improve the reliability of power supply. At present, the main methods used to detect PD signal in high voltage (HV) switchgear cabinet are transient earth voltage (TEV), ultra high frequency (UHF) and ultrasonic emission (AE). Based on a simple comparison of the above three methods, this paper reviews the TEV detection method which is widely used and has formed many standards. The physical principle, instrument composition and requirements of TEV detection method and field technical standards are summarized. The related applications including comprehensive application analysis, multi-technologies joint detection, discharge power verification and positioning, PD transmission simulation and robot application are introduced. Finally, the technology prospect of integrated composite sensor and Internet of things (IOT) is given.

In HL-2 M tokamak, three-phase thyristor power supplies are utilized to output a direct current to energize the device coil to control the plasma current and shape configuration. Phase-controlled is currently the most effective control method in thyristor power supply. The quality of the synchronization signal is directly related to the performance of the thyristor power supply control. HL-2 M device uses a pulse generator with rectifier load to supply power to the device coil, it makes the thyristor power supply AC input voltage not only have a wide frequency variation but also a severe waveform distortion, so it is difficult to obtain the accurate synchronization signal of the thyristor power supply. In this paper, a real-time tracking and processing method for variable frequency synchronization signals are proposed, which applied the digital filter with point-to-point to process varying frequency synchronization signal, calculated the real-time frequency of the filtered data, obtained the delay angles at different input frequencies according to the phase-frequency characteristics of Butterworth low-pass filter, and reconstructed the synchronization signal by phase compensation. The system has been built to achieve a wide range of real-time frequency tracking from 70 to 110 Hz, and provides multiple synchronization signal output with 15° interval. The performance of the system was verified in the HL-2A experiment.

Each magnetic field power supply is consists of three-phase full bridge thyristor converters on HL-2A Tokamak. To enhance and improve the performance of the control system of power supply system, a varying frequency three phase signal circuit has been design based on digital signal processor, which was used to control power supply on HL-2A Tokamak. This synchronous system has many advantages and is successfully applied to the operation of the power supply system in plasma discharge.