Advanced Materials Research Vol. 819

Abstract: Acoustic Doppler Current Profiler (ADCP) is one effective instrument to measure the sea current and is widely utilized in oceanographic research and ocean engineering. Some structure or frame is utilized to carry or hold ADCP in mooring system. This paper studies the hydrodynamics of different kinds of ADCP carriers and the motion of mooring system with ADCP carriers. By applying Fluent software external flow field of ADCP carrier is analyzed. Meanwhile, the velocity distribution and pressure distribution are obtained. Drag coefficients of ADCP carrier are used to analyze the mechanics and profile of mooring system with ADCP. Designing the ADCP carrier and mooring system is very useful which can provide theoretic basis for current data analysis.

Abstract: Fault diagnosis of train bearing is an important method to ensure the security of railway. The key to the fault diagnosis is the method of vibration signal demodulation. The local mean decomposition (LMD) is a self-adapted signal processing method which has a good performance in nonlinear nonstationary signal demodulation. The improved LMD method based on kurtosis criterion can prevent errors in the process of calculating the product functions. With the verification of simulation and wheel set experiment, the improvement method has been certified usefully in practical application.

Abstract: On-line monitoring recognition for machining chatter is one of the key technologies in manufacturing. Based on the nonlinear chaotic control theory, the vibration signal discrete time series for on-line monitoring indicator is studed. As in chatter the chaotic dynamics process attractor dimension is reduced, the KolmogorovSinai entropy (K-S) index is extracted to reflected the regularity of workpiece chatter, then the k-S entropy is simplified by coarse - grained entropy rate (CER), which can easily evaluated as chatter online monitoring threshold value. The milling test shows that the CER have a sharp decline when chatter occurre, and can quickly and accurately forecast chatter.

Abstract: On-line detection system of the harvester is an outcome from combination of modern computer technology and communication technology in harvester operations applications. With the help of the various sensors, the harvest yield, running routes, and threshing wheel speed, etc. are measured. These information and parameter are indicator of the harvesters working status. They are detected, processed, packed, and transmitted to the computer server in monitoring center via a wireless network. On the monitoring center server, the transmitted data is processed further, fault data are inspected, reliability data is calculated. Meanwhile, the harvester is controlled according to accepted data.

Abstract: Acoustic emission detecting has been widely used in the diagnosis of bearing fault, but nearly all of these implements require that the transducer placed close to the source of acoustic emission. However, in actual industrial environment, the transducer couldnt be mounted very close to the bearings. In this paper, the time-domain wave and time-domain features based methods were analyzed and compared among four channels at different rotating speeds. And partial analysis and some conclusions drawn from the analysis were listed below.

Abstract: A Embedded Nondestructive Testing System of Oil-well Tubing based on the method of magnetic flux leakage (MFL) is designed. The function and structure of each part of the system are analyzed. The overall structure of the system and the function of each module are analyzed. The visual data processing and analysis program of magnetic flux leakage signal based on embedded Linux Operating System is designed, and the running interface of the system is given.

Abstract: According to the characteristics and performance requirements of CNC machine, an adaptive fuzzy PID controller is designed. It uses fuzzy reasoning method to adjust the PID parameters online, and the system has good adaptive ability. The dynamic simulation of CNC machine servo system was carried out based on MATLAB. Simulation results show that the adaptive fuzzy control system has better control performance than ordinary PID control system. This method has less calculation and good dynamic quality. It is easy to implement and convenient for engineering application.

Abstract: Rolling-element bearings are critical components in locomotive traction motors. A reliable online bearing fault-diagnostic technique is critically needed to prevent motor systems performance degradation and malfunction. Motor bearing failure induces vibration, resulting in the modulation of the stator current. Compared with conventional monitoring techniques such as vibration monitoring or temperature monitoring, stator current-based monitoring offers significant economic benefits and implementation advantages. In this paper, a novel approach to locomotive traction motor current signature analysis based on wavelet packet decomposition (WPD) of stator current is presented. The effectiveness and practicability of the proposed method is verified by locomotive running tests.

Abstract: A type of pneumatic force servo system is discussed in this paper. In this system, output pressure depends on pressure difference between two chambers of cylinder; by controlling pilot-operated reducing valve will get different cylinder chamber pressure. Dynamic mathematical model and control Strategy of this system is founded in this paper. By mathematical model and control Strategy, the digital simulation results show how system performance with different gas source pressure and rodless cavity size..

Abstract: The temperature sensing characteristic of Fiber Bragg Grating (FBG) has been studied. The temperature sensing equation of FBG is revised. The accurate analysis results are obtained. The center wavelength drifts of the tested FBG are displayed in the screen of Optical Spectrum Analyzer (OSA).The experimental results show that the center wavelength of FBG is thermally red-shift with the rise of the temperature and blue-shift with the decrease of the temperature. The results are agree with the revised temperature sensing equation. It is noticed that the transmission spectrum width (SPEC-WD) of FBG fluctuates with the change of temperature. Nevertheless, the trend of the fluctuation is demonstrably towards increase, which perhaps is some potential auxiliary sensing function in future.