Applied Mechanics and Materials Vols. 373-375

Abstract: Metal-oxide surge arrester (MOA) is one of the important equipment in electrical utility company, its security and stability is critical to the safe operation of electrical equipment, and the insulation monitoring device is vital for getting the running status of metal-oxide surge arrester. Technical parameters requirements of this kind of device is discusses in this paper , and furthermore, relying on the condition monitoring technology laboratory for transmission and transformation equipment of the State Grid Corporation of China, a complete set of quality evaluation system is established, of which the following functions were realized, the total current and resistive current measurement error test, communication function test, environmental adaptability test, insulation performance test, electromagnetic compatibility performance test, mechanical performance test, enclosure protection performance test etc. With the system, a powerful technical support can be provided for the quality evaluation of the device, as well as the safe and reliable operation of the arrester.

Abstract: The house safeguard includes residential buildings earthquake prevention, fire protection, underground parking, public regional environment, and residential internal safeguard, e.g.. The house safeguard intelligent monitoring system focuses on improving the humanistic environment and building a harmonious society.

Abstract: An on-line offset current compensation method is proposed to improve ultra-high resistance (UHR) measurement more accurately and reliably. Iterative compensation algorithm is firstly adopted to generate compensation current by adjusting the compensation DAC to decrease the offset current to approximate zero, and then on-line offset current measurement algorithm is employed to ensure the time-varying offset current is always in an appropriate range. This algorithm can maintain a continuous unsaturated measurement process. Experiment results show that the uncertainty (k=2) is 1.4% for 10¹⁴Ω and 5.5% for 10¹⁵Ω under ±1000V based on the offset current compensation method proposed, which has been successfully implemented in a commercial UHR meter.

Abstract: This paper presents a diagnosis method based on EMD, in order to improve the precision of fault diagnosis in induction motors. After the Park vector analogue signal of stator current is decomposed by EMD, 2sf fault characteristic value is abstracted accurately. Simulation results show that this proposed method is of high sensitivity, efficiently solves the problem that frequencies of fault and fundamental wave are close and difficult to be decomposed.

Abstract: In order to acquire and analyze the real-time vibration signals of shearer in the process of coal mining. This experiment used the portable vibration measurement data recorder, which developed by ourselves. We design a comprehensive set of solutions for data acquisition according to underground mining machines working in real time. Through the data collection package, obtained a shearer vibration signal sample on real-time working. Meanwhile, analyze the vibration signal using signal analysis method. Through the experiment we acquire vibration signals of shearer's ranging-arms on real-time working, and the analysis results indicate that data collection solution is reasonably practicable.

Abstract: Due to the narrow interior space of vehicle, the compact structure limited the method of revolution speed measurement based on photoelectric and magnetoelectric, so a new measurement method based on capacitive grating sensor is presented here. The sensor will output alternating capacitance signal by fixed the mobilizable grating on the shaft and fixed the stator grating on the bracket. The capacitance signal will turn into the corresponding sine wave signal to the speed through differential pulse width modulation circuit, subtraction circuit and low-pass filter circuit, and will output a square wave of the same frequency with the sine wave through phase locked loop circuit. Then the speed measurement will be realized by counting the signal pulse. Experiments show that this method has the characteristics of non-contact measuring and high sensitivity.

Abstract: In wayside fault diagnosis of train bearings, the phenomenon of Doppler distortion in the acoustic signal of moving acoustic source acquired with a microphone leads to the difficulty for signal analysis. In this paper, a new method based on Dopplerlet transform and re-sampling is proposed to eliminate the Doppler distortion of multiple acoustic sources which provide a reference for wayside fault diagnosis of train bearings. Firstly, search the parameters space to find the primary functionsDopplerlet atoms. According to the Morse acoustic theory, the instantaneous frequency of the Dopplerlet atom which we choose to remove Doppler distortion of the corresponding acoustic source can be acquired. Then, the re-sampling sequence can be established in time domain. Through the resample, the Doppler distortion can be removed. In the end of this paper, an experiment with practical acoustic signals is carried out, and the results verified the effectiveness of this method.

Abstract: To reduce the computational complexity of direction finding algorithms based on correlation processing, a fast algorithm is presented in this paper. Unlike the conventional direction finding algorithms which calculates the correlation coefficients in the whole azimuth range, the improved algorithm measure the direction of arrival (DOA) roughly first, then, measure the DOA only in finite angle interval and searches the maximal correlation coefficient, thus shorten the execution time greatly. In addition, the algorithm has no influence on the accuracy of direction finding. The best proportion between samples for rough measurement and samples for fine measurement is analyzed. Computer simulation results confirm that the proposed method can shorten the computation time greatly, and the proposed algorithm has practical application value in the instantaneous direction finding.

Abstract: A generator bearing temperature measuring system is designed, based on the LabVIEW8.6 and virtual instrument technology, in this paper. The hardware and software implementations of the system are introduced. The system is tested and analyzed both in algorithm of linearity and filtering effect. The experimental results show that the proposed system has good characters of good stability and high accuracy, which are valuable in engineering application.

Abstract: This paper introduced the laboratory model of Real-time monitor system based on the 3D Visualization for calefaction furnace, depicted the process of the model.In this paper we created a virtual environment and transport the real-time data which we collected from the locale to the virtual scene,to realize the real time monitor on the real environment.Through simulating in the lab,the effect of this system was realistic at the same time it arrived at the goal of better monitoring with better real-time.