Applied Mechanics and Materials Vols. 220-223

Abstract: In order to improve the prediction accuracy and reduce the influence caused by earthquake disasters, the method of predicting the earthquake is proposed. The method aim at nonlinear problems, limitation in training samples and unbalanced distribution that exist in the earthquake prediction, according to the sample the method build training and forecast BP network. The results of simulation experiments prove that the method is feasible and also helpful to improve the accuracy of earthquake prediction, because of less error.

Abstract: Subgrade compaction is an important task in modern traffic fields, where GPS ranging technology is one of the key technologies in intelligent compaction. In the paper, NMEA communication protocol was illustrated, the statement of GPGGA was analyzed, and the extraction of the single point geographical coordinate was realized correspondingly. Aimed at the phenomenon of data loss in signal drift and data acquisition, the missing data estimation algorithm for longitude and latitude was adopted to obtain the complete data sets as well. Finally, the deficiencies of the traditional longitude and latitude distance measuring formula were analyzed and a new model of measuring distance of longitude and latitude was discussed. The experimental results show that the method has the better stability of measurement, the higher test accuracy, which has a good application prospects in intelligent compaction. However, the real-time property of data processing still needs further research.

Abstract: This paper mainly introduces the design ideas of data acquisition system for wave energy conversion efficiency test system and the usage of data acquisition card.Visual C++6.0 is used as the design platform for the design of the software. The acquisition process is controlled by the multimedia timer and the real-time multi-channel data is collected through the data acquisition card Then the real-time data curve is displayed on the software interface. The collected data can be used as an effective basis for optimizing energy conversion devices.

Abstract: This paper examines a new measure of the detection end antenna model designed to the frequency-selective level,broadband electric-field probe.It is based on double layers printed dipole which overcomes the difficulties found in the prototype transfer-standard electric-field probe which put forward by NBS in 1986.The difficulty of fabracation is fallen and it realize the performance of the standard E-field probe using traditional single layer structure dipoles.It is much easier to fix the antenna.The main theme of the paper is to extend the utilization of the double layers printed antenna using the theory of resistively tapered dipole for broadband E-field probe’s antenna.This double layeres printed dipole element allow a analysis of gain frequency response curve flat within 0-2.5dB from 11.8GHz to 15.2GHz,and obtain a stable isotropic response.

Abstract: For the vehicle emission pollution has become to be a serious problem, with the use of GPRS/GSM wireless communication technology the automobile exhaust emission information can be sent to the remote central server, realizing the purpose of remote monitoring management. This paper introduces the composition and working principle of this system which uses the three-layer structure of car-terminal, wireless network and PC monitoring center. And emphatically studies one kind of methods based on the generic TCP protocol, Socket, multiple threads technology and ASP.NET technology to realize the B/S mode monitoring system communication.

Abstract: In this paper, a wavelet-based pipeline inspection method was illustrated experimentally. Piezoelectric ceramic (PZT5), as sensors, was used to generate and receive the guided wave signal. To be specific, a piezoelectric ring was an excitation sensor in order to generate L(0,2) mode guided wave and 16 evenly distributed piezoelectric patches in pipe circle were the reception sensors. A transverse artificial notch in the pipe wall could be detected successfully by the guided wave. For reducing the noise from the testing signal, a wavelet-based denoise technique was proposed Based on the denoised signal, both location and size of the defect could be identified. The result shows that the crack size identification was in good agreement with the theoretical prediction.

Abstract: The relative direction for a constant speed can be determined according to the planar non-circular curve parts. To establish the mathematical model, a constant speed motion simulation system is designed. The parameters of (v_H=5mm/s, δ<3") is commonly used for the simulation system to simulate the movement of drawing the error curve. The results show that by controlling the movement of the plane curve parts in mathematical model can derive the basic constant speed, the relative error of constant speed is less than 3%, it provides a reliable bias when apply to production practice.

Abstract: In order to improve the power frequency voltage ratio standard calibration techniques to meet the application of UHV power grid，a measuring circuit based on power frequency voltage linear superposition method was proposed. A three-port network was fromed by connecting two shielding voltage transformer with the same rated voltage ratio in series. The voltage coefficient of a voltage transformer was tested by double voltage method based on the proportionality and superposition of the linear network. The measuring circuit based on power frequency voltage linear superposition method can prevent the shielding error of the voltage transformer during the mearurment, making it used in voltage ratio standard self-calibration system with higher voltage and precision. The test has proved the feasibility and accuracy of circuit of power frequency voltage linear superposition method.

Abstract: A test method of current leakage for dielectric paste was proposed by simulating the application processes of dielectric paste for manufacturing the dielectric layer in the multilayer thick film hybrid microcircuit. That is, by screen printing and sintering processes, the sliver conducting layer was fabricated on the surface of glass substrate, and then dielectric layer, finally the glass substrate sample with conducting layer and dielectric layer was dipped in 5 Wt% NaCl aqueous solution. The conductive line was soldered on the silver conducting layer to form the test circuit, and powered with 5 volts direct power, the current in the test circuit was taken as the current leakage of the dielectric paste. The method may be used to evaluate the current leakage of dielectric paste.

Abstract: With regard to goafs where spontaneous combustion of coal is very likely to occur, wireless monitoring and early warning techniques in temperature field of goaf are raised. Wireless monitoring and early warning system in temperature field of goaf based on wireless sensor network is researched and developed. Comprehensive detection, identification and early warning in temperature field of goaf are realized. Key parameters of node deployment of wireless temperature sensor in goaf are figured out and the layout schemes are optimized. According to monitored temperature information, severity of coal spontaneous combustion in goaf is figured out; therefore, early warning methods at the position of fire source are determined. Results of industrial tests on site show that monitoring data acquisition, communication are of good timeliness and reliability, operation of the entire system is stable and key functions and technical specifications can meet the need of early identification and warning of coal spontaneous combustion.