Applied Mechanics and Materials Vols. 220-223

Abstract: Principle of the pipeline leak detection system is presented, and the leak detection method based on acoustic wave and wavelet analysis is studied in this paper. The dynamic pressure transmitter based on piezoelectric dynamic pressure transducer is designed. The characteristic of dynamic pressure transmitter when pipeline leak happened is analyzed. The dynamic pressure signal is suitable for pipeline leak detection for quick-change of pipeline internal pressure, while the static pressure is suitable for slow-change of pipeline internal pressure. The signal is analyzed by wavelet analysis method to detect the singularity, and the singularity is used to recognize and locate the leak. This paper indicated that the dynamic pressure signal could be adjust to this detection that the pressure changes in the pipeline. Field tests in 68.2 km pipeline segment show that the method detects pipeline leak rapidly and precisely.

Abstract: Based on the requirements of special equipment safety and the current status of recreation facilities test system, a fault diagnosis system for roller coaster was designed. The signal acquisition device was designed, taking digital signal processor as the main control chip. High-frequency vibration acceleration signal and low-frequency motion acceleration signal were acquired. And the data were transmitted to upper computer. By using LabVIEW, the software of upper computer was developed. FFT analysis and wavelet analysis were applied to process the data. BP neural network was applied to fault diagnosis. The test result shows that the system is quick, accurate and reliable.

Abstract: It is presented that a novel concept to estimate the shape of inner hole and calculate the location of reversing point in course of honing in this paper. Based on analysis of machining condition, Simplified slope measurement model is established in pneumatic measurement system for inner hole honing. The method and principle are elaborated in this article. The model can accurate the accuracy of machining area in inner hole. Program module was designed and written for experiment. And the experimental data show that the measuring model is feasible

Abstract: In order to solve the problem of siphon rainfall recorder’s hard to control automaticly and the measurement error when siphoning, we research the Automatic forecasting system based on double barrel double siphon rainfall recorder and ARM processing terminal. By using double barrel double siphon structure and weighing cell, we eliminate the rainfall error caused by siphon loss, and achieve the automatic collection of rainfall data.

Abstract: Abstract: In this article, a three-hydraulic-cylinders synchronization control model of the hydraulic system of a large dump truck is discussed and the proportional integral (PI) control is used for the hydraulic system. Simulation and performances comparison between the improved and unimproved system have been done by using MATLAB 7.10. To meet different practical engineering requirements, different control methods are designed and selected，aiming to the practical purpose.

Abstract: Hydrodynamic force is one of the important factors to be considered in the design of hydraulic valves. In this paper, mathematical formula of steady hydrodynamic force was deduced basing on non-circular opening spool valve structure and working principle. The simulations were carried out with software FLUENT at differential pressure, different valve port openings, and then the variation of the steady hydrodynamic force can be obtained. The results show that the direction of the steady hydrodynamic force is opposite to the movement of the valve spool and tends to close the valve port; the magnitude of the steady hydrodynamic force is proportional to the valve opening and differential pressure respectively.

Abstract: In order to study the Application of high-speed on-off valve in the hydraulic cylinder speed control system, series and parallel application schemes between high-speed on-off valve and hydraulic cylinder are proposed to control the speed of hydraulic cylinder. The duty cycle of pulse control signal was changed according to the displacement of hydraulic cylinder to control the speed of hydraulic cylinder and weak the impact. The simulation curve compared with the experimental results show that, two application schemes can both control the speed of hydraulic cylinder effectively. Series application scheme can be only applied to small flow hydraulic system; parallel application scheme has wider application.

Abstract: For the purpose to provide a reference for ecological floating island construction of Liao river, this paper simulated different flow velocity to research the stability of floating island with different fixation methods based on the actual hydrological data of Liao river at the comprehensive experimental base of Shenyang agricultural university. Results show that the stability of floating island with different fixation methods under different flow velocity have significant difference. The data of longitudinal displacement shows the stability of staking floating island is best, the following one is cableway and the sinker is worse. The data of lateral displacement shows the stability of cableway floating island is best, the following one is staking and the sinker is worse. The data of vertical floating displacement shows the stability of cableway floating island is best, the following one is sinker and the staking is worse. Comprehensively, the stability of cableway floating island is best, staking is better and the sinker is less stable. Consequently, this study recommended the cableway and staking floating island as the ideal types in experimental construction in Liaohe river.

Abstract: For providing refer to the experimental data of artificial floating island in river north, this study will get stability characteristics of artificial floating islands displacement pile fixation on simulating the impact of different flow rate of water. Analysising physical stress of artificial floating island displacement pile fixation and simulation, result shows that the sum of floating island of buoyancy and the maximum force of two fiber rope in the vertical direction should be greater than the maximum gravity of the floating island plants and ensure the maximum force of the two fiber rope in the horizontal direction must be greater than the flow momentum, the quality of floating island can be increased for improving stability. Depend on the different flow of water and linear regression equation, the distance between the floating island should be arranged reasonably.

Abstract: This paper studies the flow pulsation of axial piston pumps of different cross angles based on CFD simulation. The swash-plate cross angle of piston pump affects the piston pump outlet flow pulsation by changing the contraction amount of the plunger in the valve plate transition zone. First, we established the flow pulsation model with swash plate cross angle based on the noise reduction principle of the swash plate cross angle, and studied the influence of cross angle of different rotation angels on the flow pulsation based on CFD simulation. The conclusion is that the maximum and minimum peak of the flow pulsation decreased when the rotation angle of the cross angle is greater than 1 °; the maximum and minimum peak of the flow pulsation increased when the rotation angle of the cross angle is less than -1 °; a good noise reduction can be got when the piston pump cross angle rotates 1°.