Search

Aluminum alloy structures may be damaged due to wear or corrosion while in service. These damages will bring about huge financial costs, as well as a huge amount of energy consumption. There is an urgent need to search for an appropriate repair method in order to solve this problem. In this research, the cold spray process was used to repair the damages by using a mixture of powders with Al and Al2O3. A 7N01-T4 aluminum alloy plate with a factitious pit was regarded as the damaged sample. The microstructure, mechanical properties, and corrosion behavior were studied. The results showed that there were no visible perforative pores or cracks in the repaired areas. The microhardness of the repaired areas was in the range of 57.4–63.2 HV and was lower than that of the 7N01-T4 aluminum alloy. The tensile strength of the repaired samples was markedly improved compared with the unrepaired samples. The alternate immersion test results indicated that the repaired samples had the lowest rate of mass loss compared with 7N01-T4 and the unrepaired samples. After alternate immersion tests for 504 h, the repaired samples were covered with dense corrosion products. The repaired samples had a superior corrosion resistance compared to that of 7N01-T4. Thus, the cold spray process is a method of repairing damage in aluminum alloy structures.

In order to diagnose the electric shock fault types of new-generation adaptive residual current operated protective devices (RCDs), a combination method based on local mean decomposition (LMD) amount of energy and support vector machine (SVM) is proposed in this study. First, LMD is applied to decompose the original electric shock signals into a finite number of product functions (PFs); then the former PFs containing the main features are selected to calculate the total energy. Second, SVM is used to solve the multi-class classification problem. The amount of energy of the PF component is considered as the input vector of the SVM, and particle swarm optimization (PSO) is used to optimize the model parameters. Experimental results show that the proposed method is effective in diagnosing animal or plant electric shock fault type, which provides a reliable theoretical basis for developing a new generation of adaptive RCDs. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The electrical shock fault signal is very important to the protection and control of power system. However, in practical cases, the signal is usually corrupted by artifacts through the recording process. Thus, denoising of this type of electric shock fault signals seems necessary. In this paper, a novel method for denoising electriccal shock fault signals is proposed based on Empirical mode Decomposition-Thresholding (EMD-T). With the new method, the nonlinear and non-stationary fault signal is decomposed into intrinsic mode functions (IMFs) via EMD, then, mixed modes will be processed by threshold denoising approach. The efficiency of the method is applied on real electric shock fault signals and white Gaussian noise added electrical shock fault signals obtained from Residual Current Operated Protective Device experiment platform. Signal to Noise Ratio (SNR) and Root Mean Square Error (MSE) are used to measure and compare the performance of proposed method with traditional FIR based method. Results show that EMD-T algorithm performs better than conventional FIR filter method.

The Block 3/7 of Sudan Oilfield has been in the period of high water production. The water cut of many wells is more than 80%, and still rising. Besides, there are many sandy wells in this area. In order to reduce the water cut, the conventional technique involves two string trips—water detection primarily, and then water shutoff treatment according to the result of testing. Obviously, high cost and low efficiency restrict its application. Therefore, based on the conventional technique, a new integrated technique for servo adjustable water detection and water shutoff has been researched by Daqing Oilfield Limited Company, which is mainly made up of drillable packers to divide layers, intelligent controlled piezoelectric valves, inserted seal sections and releasing subs. With the integrated technique, dynamic adjustment and water shutoff treatment can be achieved at any layer without pulling the string upward or downward. Applying casing pressure signals can open the appointed position’s valve when detecting water, then get its single layer’s production, meanwhile record and test on the ground to confirm this layer’s production and water cut. Applying casing pressure signals closes the appointed position valve after testing. Repeating the above steps can get all the layers water production and water cut. According to the result of water detection test, open the intelligent controlled piezoelectric valves of the lower water cut layers to stabilize the oil production. This new technique has been successfully applied to 8 wells in the Block 3/7 of Sudan Oilfield, which features low cost and high efficiency. It could meet the requirements of water detection and water shutoff for the remaining 30 wells of high water production. Similarly, it could apply to many wells of high water production in Daqing Oilfield.

Power Cable Joint is the area where the faults are often happening on the power cable. Real-time monitoring of Power Cable Joint temperature can discover the joint overheating, and can evaluate insulation aging degree, and then, potential safety hazard of the cables will be removed timely. In this paper, a temperature measurement method based on embedded sensors inner Power Cable Joint has been proposed, and a set of temperature monitoring system for Power Cable Joint has been developed. The temperature monitoring system was composed of embedded sensors, data acquisition unit, current induction power supply, data transmission based on combination of ZigBee and GPRS, data analysis software. The temperature measurement system has the advantages of high reliability, real-time and highaccuracy, the long-distance temperature measurement for Power Cable Joint has been achieved.

Article studied asynchronous motor phased light load regulator of the principle of energy saving voltage regulator from the theory, impact of power efficiency of three key factors when the light load: Voltage, slip and power factor, proposed power-saving conditions. Running from the energy savings of view, in theory set up the ideas of the smallest energy consumption optimization target power factor COS ?j and determine formula of the optimum voltage adjust Uij by the load rate to. And to propose an automatic minimum energy optimal voltage control concept and technical realization method.