Advanced Materials Research Vols. 926-930

Abstract: With the rapid development of computer technology, Visual simulation technology is mature, widely applied to every field of education, teachers and students benefit, the teaching effect has improved significantly. From the characteristics, function of visual simulation technology, visual simulation technology are introduced in the sports teaching the application of visual simulation system design a set of sports training. The system construction of virtual scene by using the method of training detail step by step, based on the three-dimensional image VRP interactive platform for the development environment, visual simulation for sports training. The practice proved: the system simulation is high, achieved the effect of sports training simulation, and operation flow.

Abstract: The original near infrared spectral (NIR) inevitably includes noise signals and usually has a large amount of data. So de-noising and compression are the main tasks of spectral data pretreatment, in order to improve the accuracy of model prediction and modeling speed. Traditional spectral pretreatment methods have their own limitations in these two aspects. In this paper, the wavelet analysis method was applied to preprocess apple NIR data. Compared with Savitzky-Golay smoothing method and multiple scattering correction , the wavelet method has its own superiority in noise removal and data compression.

Abstract: With the problem of magnetic anomaly signal in low SNR, we using empirical mode decomposition (EMD) algorithm and Savitzky-Golay filter to solve weak magnetic anomaly signal in noisy environment detection problem. With the EMD, the weak magnetic anomaly signal can be decomposed into different numbers of sub-signals called intrinsic mode functions (IMFs). The IMFs include signals different frequency component from high to low. Recover the signal with IMFs which correlation coefficient is low with noise signal and smooth the signal with Savitzky-Golay filter. The proposed method is verified by simulation on computer. The present experimental results show that this method is effective to detect the weak magnetic anomaly and recover the original signal.

Abstract: With the rapid development of laser technology and wide use of laser application, the application of the interaction between laser and target material in liquid environment is becoming more and more widespread. The research of interaction between laser and target material in liquid environment also becomes increasingly important. In this paper, in order to explore the interface interaction between the high-energy microsecond laser and underwater aluminum target material, the solid-liquid interface pressure field, turbulence and the distribution of the flow field are observed. Research shows that during the interaction between laser and target material, the speed of mixture in the light spot area smaller than that in the speckle fringe. And during this period, bubble pulsation would happen.

Abstract: Compared with continuous laser, pulsed fiber laser has the advantages of high peak power, which is widely used in device processing, military defense and other areas. As the repetition frequency of pulsed fiber laser is low and therefore it cannot realize high rate transmission, this paper does the research on L-PPM modulation of pulsed fiber laser to find a method of effectively improving the modulation rate of pulsed fiber laser. Experimental results show that the L-PPM modulation can improve the transmission rate of the pulsed fiber laser whose repetition frequency is 200K to 1.387Mbps. The research results are useful for the application of pulsed fiber laser in communication.

Abstract: The voiceless consonant [h] can be collocated with the voiceless plosives, voiceless affricates, voiceless fricatives, nasals, laterals, etc. This paper makes a study on different collocations with duration and spectrum, with the result , it is can be seen that, the differences are greater among the acoustic characteristics of [h] as initial consonant and prepositional consonant, and that present the different ways of pronunciation.

Abstract: Vector-hydrophone can simultaneously measure acoustic pressure and orthogonal components of the particle velocity. The 180o ambiguity in DOA estimation can be eliminated using information obtained by vector hydrophone array. Multiple signal classification algorithm is a method that takes the eigen-decomposition of data co-variance matrix to obtain the estimation of signal spatial spectrum. The two-dimensional DOA of acoustic sources is estimated based on multiple signal classification algorithm using the vector-hydrophone uniform linear array. Simulation results show that better DOA resolution performance can be obtained from vector hydrophones. Furthermore, the paper takes the de-correlation of correlated sources using spatial smoothness technology to obtain perfect performance of two-dimensional DOA estimation.

Abstract: This paper puts forward a kind of gearbox fault diagnosis methods which based on empirical mode decomposition (EMD), Hilbert transform, Fast Fourier Transform (FFT) and spectrum refined techniques. This method is applicable to the analysis of the nonlinear unsteady signal. First of all used wavelet denoising to the acquisition of gearbox vibrate signal, again carries on the empirical mode decomposition (EMD), than get a certain number of intrinsic mode function (imf); Choose the specific imf, based on kurtosis value, after the Hilbert transform and Fast Fourier Transform is done, the corresponding power spectrum can be obtained; To refine the power spectrum and extract the gearbox fault characteristic frequency; Then in pattern recognition and diagnosis of the gearbox fault, and compared with the normal signal characteristics. The analysis results show that the proposed method can effectively detect the gearbox fault characteristics.

Abstract: In this paper, we propose a new method using teager energy operator and entropy to solve endpoint detection problem in noisy environment. With the teager energy operator, it is sensitive on AM and FM signal and noise suppression capability on noisy speech signal, calculate teager energy of noisy speech signal. According to the different teager energy probability distribution between noise and speech signal, teager energy entropy is different. Set two soft thresholds of four states to detect the endpoint of noisy speech signal. The simulation shows that the method has good effect of endpoint detection in low SNR conditions, the simulation results show that teager energy entropy of speech signal endpoint detection in noisy environments is feasible and effective, and improves the reliability of endpoint detection.

Abstract: This article describes a method of IF modulation used in millimeter-wave transmitter, the method is AD9857 combined with FPGA, choose the EP1C6 as a FPGA chip, and use this FPGA chip complete the base-band digital signal processing, and implement the control to the AD9857. AD9857 is a kind of the orthogonal frequency converter based on DDS technology, complete the functions of base-band digital signal interpolation filter, orthogonal modulation, and D/A conversion in the digital domain and complete QDPSK modulation signal output of 70MHz IF carrier. This method can eliminate phase and gain imbalances and distortion which caused by analog modulation, also can simplify the system structure, reduce cost and improve the performance and reliability of the system.