China Three gorge University

Yichang, China

China Three gorge University

Yichang, China
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Li D.,Chongqing Three Gorges University | Li H.,China Three Gorge University
Advanced Materials Research | Year: 2012

In this paper, an efficient algorithm for computing 10-point DFT, radix-10 FFT algorithm for computing 10 M-point DFT and N=L×10 M-point DFT are presented. FFT is often employed in power systems harmonics analysis even though it is not accurate due to spectral leakage and barrier effect. When N=L×10 M-point DFTs are used to analyze harmonics in power systems, comparing to N=2 M-point DFTs, very accurate harmonic parameters can be obtained. The simulation results in MATLAB show that the methods are feasible and effective to enhance analysis accuracy. © (2012) Trans Tech Publications, Switzerland.

Li H.,China Three Gorge University | Fei R.,Chongqing Three Gorges University
Proceedings - International Conference on Electrical and Control Engineering, ICECE 2010 | Year: 2010

An efficient algorithm for computing 10-point DFT, which can contribute fast algorithms to more N-point DFTs, is developed. The computation of one 10-point DFT requires only 20 real multiplications, 84 real additions and 4 real right-shiftings 2 bits. According to the principles of decimation-in-time (DIT) or decimation-in-frequency (DIF) or double factors algorithm and the efficient algorithm of 10-point DFT, 10M, 10×M, 2M×10, 4M×10-point DFT have their own efficient algorithms, respectively. Thus, many N-point DFTs are possessed of own fast fourier transform algorithms. Especially, in efficient algorithm for computing 10-point DFT, in other words, in radix-10 FFT algorithm, one 102-point DFT requires 720 real multiplications, 1840 real additions and 80 real right-shiftings, one 103-point DFT requires 12760 real multiplications, 28580 real additions and 1200 real right-shiftings 2 bits, and one 104-point DFT requires 183560 real multiplications, 387780 real additions and 16000 real right-shiftings 2 bits. © 2010 IEEE.

Zeng T.-L.,Chongqing University | Wen Z.-Y.,Chongqing University | Wen Z.-Q.,Chongqing University | Zhang Z.-W.,Chongqing University | Wei K.-L.,China Three Gorge University
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2013

The water quality monitoring technology based on ultraviolet spectrum analysis has the characteristics of small volume, low cost, and no secondary pollution, and it doesn't need any reagent and sample pretreatment. On account of these characteristics, the direct ultra-violet technology has remarkable superiority over traditional technologies when applied in online monitoring of drinking water, surface water and industrial wastewater, and it has become an important development tendency of modern water monitoring technologies. The principle, characteristics, present situation and development trend of modern water quality monitoring technology based on ultra-violet spectrum analysis were introduced, and the key technical problems were further discussed in this paper.

Zhang Z.-W.,Chongqing University | Wen Z.-Y.,Chongqing University | Zeng T.-L.,Chongqing University | Wei K.-L.,China Three Gorge University | Liang Y.-Q.,Chongqing University
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2013

The method based on miniature near-infrared spectrometer combined with Y fiber optic probe to detect the protein and fat in milk powder by diffuse reflectance spectroscopy in the wavelength range of 900~1700 nm was proposed. By selecting the appropriate spectral bands, the correction models of protein and fat were established with partial least squares algorithm using Unscrambler 9.7 Chemometrics software. The determination coefficients R2 of the correction modes are 0.987 and 0.986 for protein and fat respectively, and the root mean square errors RMSEC are 0.385 and 0.419 respectively. Using these correction models to predict the protein and fat contents with 30 sets of forecast sample data, the prediction standard deviation is SEPProtein=0.751 for protein, and is SEPFat=1.109 for fat. The results indicate that these correction models have prediction capability with unknown samples and meet the on line requirements.

Chen H.-K.,Chongqing Jiaotong University | Chen H.-K.,China Three gorge University | Tang H.-M.,Chongqing Jiaotong University | Wang Z.,Chongqing Jiaotong University | He X.-Y.,Chongqing Jiaotong University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

The excitation effect of perilous rocks is one of main impact factors to induce the chain damage of unstable aggregation rock blocks. Aiming at a falling perilous rock, a laboratory model test for testing its excitation effect was conducted. The test results showed that firstly, the quality effectiveness of the excitation signals can be determined with the coherent coefficient analysis method, and almost all the measured excitation signals of unstable rock are distributed in a3 (0~1250Hz) frequency range; secondly, the time-history curve for each wavelet decomposition coefficient of an excitation signal can be gained with the db8 (3 layers)wavelet analysis method, and its spectrum figure can be obtained through Fourier transformation; thirdly, the excitation signal totally presents an attenuation trend, and it has three peak values at 900Hz, 1100Hz and 1500Hz; the larger the distance between a measured point and the fountainhead of an excitation signal, the bigger the excitation acceleration, and the excitation acceleration in the vertical direction is bigger than that in the horizontal direction; fourthly, the better the integrality of interface between two perilous rocks, the easier the transfer of excitation signals, and the decay rate in the vertical direction is higher than that in the horizontaly direction. The results had a positive effect on revealing the damage mechanism of group-occuring unstable rock blocks.

Chen H.-K.,China Three Gorge University | Chen H.-K.,Chongqing Jiaotong University | Yang M.,China Three Gorge University | Tang H.-M.,Chongqing Jiaotong University | And 2 more authors.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

As one of emergency geological disasters, perilous rock releases abruptly energy during rupture. The energy passes through perilous rock blocks near the rupture position in the form of excitation wave, and it decreases the stability of perilous rocks near the rupture position. Here, by de-noising processing with the wavelet method of excitation signals gathered in a model test of falling perilous rock rupture in laboratory, the signals during 10 ms duration from the 25 ms to 35 ms in the model test were taken as the essential data to analyze local and minutiae characteristics of excitation signals during perilous rock rupture. Under the test conditions, analysis results showed that local characteristics of excitation signals during perilous rock rupture have a certain periodicity, i. e., 8 or 9 excitation peaks with 1.0~1.4 ms periods exist in horizontal direction, while 3 or 4 excitation peaks with 2.2~3.0 ms periods in vertical direction; the distance between the measuring point and the rupture position significantly affects the amplitude of excitation peaks, the closer the distance, the bigger the amplitude; furthermore, the integrity of the interface between two perilous rock blocks has a significant impact on the frequency and amplitude of excitation peaks, when an excitation signal passes through an incomplete interface, the peaks of the excitation signal are lagged a little, the time-delay is about 10 ms under the tests; specially, almost all local and minutiae characteristics of excitation signals during perilous rock rupture can be embodied with minutiae coefficients, the main frequency of excitation signals appear in minutiae characteristics from d3 to d7. Achievements gained here were helpful for implementation of similar model tests of excitation effect during perilous rock rupture. ©, 2014, Chinese Vibration Engineering Society. All right reserved.

Zeng M.,China Three Gorge University | Zhao Q.,China Three Gorge University | Fang C.,China Three Gorge University
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011 - Proceedings | Year: 2011

Controlling structures and properties of controller effect dynamic properties of all the system in AC servo system. Base on PMSM, regulating the current loop of AC servo system is the basic of high performance servo systems. Three loops controlling structure of AC servo system was analyzed by this paper. In this paper, dynamic mathematical model of closed current loop were established and simplified. The controller of current loop was designed. The system was corrected by the controller. In NC gear milling machine, tuning and calculation of the current loop was carried in MATLAB/SIMULINK. The result indicated that the tuning of current loop enhanced the rapidly of the system and inhibited the internal interference of the current loop. Properties of the system were enhanced. © 2011 IEEE.

Wu Z.-J.,China Three Gorge University | Wang W.,China Three Gorge University | Zhou J.,China Three Gorge University | Ren F.-F.,China Three Gorge University | Zhang C.,China Three Gorge University
Proceedings - 2010 International Conference on Computational Intelligence and Security, CIS 2010 | Year: 2010

The master production schedule (MPS) problem is a typical NP-hard problem. In this work, A MPS optimization model whose objectives are maximum utilization of equipment and minimum ratio between storage expenses and overdue fines is established with equipment capacity and product lead time as constraints. Then this model is implemented using a product encoding method and newly designed ant path searching process according to its characteristics. Finally, an example is given; the result indicates that this algorithm is effective and feasible. © 2010 IEEE.

Liu W.,China Three Gorge University | Shen Y.,China Three Gorge University
Proceedings of the 30th Chinese Control Conference, CCC 2011 | Year: 2011

In this paper, the problem of finite-time H∞ control of linear singular systems with an exogenous disturbance is considered. By using the method of linear matrix inequality, it can be proved that the designed state feedback controller guarantees the closed-loop system is finite-time bounded and satisfies the conditions of H∞ control. In the end, an example is given to show the validity of the proposed approach. © 2011 Chinese Assoc of Automati.

Li H.,China Three Gorge University | Yan Q.,China Three Gorge University | Ji P.,China Three Gorge University
Asia-Pacific Power and Energy Engineering Conference, APPEEC | Year: 2011

This paper introduces a new strategy for power systems harmonics analysis based on N=L × 10 M-point DFTs. When the fundamental frequency of a power system signal is 50 Hz, a sampling frequency 2000Hz is selected, N=L × 10 M-point DFTs can reduce spectral leakage and obtain high accuracy harmonic parameters. The simulation results in MATLAB show that the strategy are feasible, and comparing with the harmonic analysis method based N=2 M-point DFTs in radix-2 or radix-4 FFT algorithm, the harmonic analysis method based N=L × 10 M-point DFTs has the obvious superiority. This new strategy maybe open up a new ideas for power system harmonic analysis. © 2011 IEEE.

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