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Liu F.,Yanshan University | Liu F.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Liu B.,Yanshan University | Liu B.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | And 3 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2015

Considering the dynamic characteristics of the rolling force influenced by roller vibration, a nonlinear vibration model of strip mill roll system was established. Average method was adopted to get the amplitude frequency response of the vibration system, the amplitude frequency characteristics of the system were analyzed with the changing rolling speeds and external excitation amplitudes. The singularity theory was used to analyze the static bifurcation behavior, and to get the transition set and the critical conditions of different forms of vibration behavior of this system. The dynamic bifurcation behavior was researched with the changing rolling speeds. The results show that vibration behavior of rolling mill is very sensitive to the changing rolling speeds, the vibration amplitude increases with the increasing of excitation amplitudes and rolling speeds, the frequency range of instability decreases with the increasing of rolling speeds, increases with the increasing of external excitation. The intermittence chaos is appeared with the changing of rolling speeds, and the speed range of steadying rolling is obtained with the maximum Lyapunov exponent curve. The results provide a theoretical reference for the vibration suppression and guarantying stable operation for rolling. ©, 2015, China Mechanical Engineering Magazine Office. All right reserved.


Li D.,Yanshan University | Zhang Y.,Yanshan University | Zhang Y.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Fu X.,Yanshan University | Fu X.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province
Guangdian Gongcheng/Opto-Electronic Engineering | Year: 2014

A new method which combines the Simplex code with the average superposition algorithm-S superposition algorithm is proposed . In the condition of the same denoising effect of the two methods, S superposition algorithm can substantially reduce the number of superposition to reduce the time of the signal processing and solve the problem brought by the length of Simplex code. In order to verify the correctness of the S superposition algorithm, create mathematical model of the distributed optical fiber sensing system. Simulation experiment is launched with the mathematical model. The results of the simulation experiment show that the S superposition algorithm can greatly reduce the signal processing time. It proves the correctness and validity of the new method.


Zhu Q.,Yanshan University | Zhu Q.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Wang Z.,Yanshan University | Chen Y.,Yanshan University
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2016

Aiming at the problems that the image feature extraction and match algorithm should have high accuracy, good performance in real-time and robustness when the mobile robot navigated based on topological map, the paper proposed a new image hierarchical matching algorithm based on the global feature and local fusion. First, the improved shape context algorithm was applied to the input images to be matched to extract the global features which were matched roughly with the images in the database, obtaining 3 images that had the highest similarity to the current image which constituted a temporary image database. Then, the improved SIFT algorithm were used to extract local feature of the input images which were matched accurately with the local feature of the 3 images in the temporary image database, finally obtaining the image with highest similarity as the match results. The image hierarchical matching algorithm based on the global feature and local feature combined the improved shape context algorithm based on global features and the improved SIFT algorithm based on local features, so as to achieve the purpose of complementary advantages. The experimental results show that this algorithm can effectively improve the matching efficiency and reduce the running time when the mobile robots navigate based on topological map. © 2016, China Mechanical Engineering Magazine Office. All right reserved.


Zhang Y.,Yanshan University | Zhang Y.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Wang G.,Yanshan University | Fu X.,Yanshan University | Fu X.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province
Guangdian Gongcheng/Opto-Electronic Engineering | Year: 2016

A multiple wavelength demodulation method of long period fiber grating and fiber Bragg grating is proposed. Fiber Bragg grating can reflect the long period fiber grating transmission light. The central wavelength shift of fiber Bragg grating will cause the change of reflected light power, and the photoelectric conversion voltage can also change accordingly. So the voltage can demodulate the central wavelength. Because the transmission spectrum of long period fiber grating is very wide, the bandwidth of fiber Bragg grating is so narrow, and a long period fiber grating can demodulate a lot of fiber Bragg gratings. The experimental results show that the voltage of central wavelength and the photoelectric conversion of fiber Bragg grating have a good corresponding relationship. The demodulation method has some advantages including simple structure and high accuracy, so it can be used to measure the parameters of temperature and strain. © 2016, Editorial Office of Opto-Electronic Engineering. All right reserved.


Chen W.,Yanshan University | Chen W.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Zhang X.,Yanshan University | Zhu Q.,Yanshan University | And 2 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2015

For the problems of slow image processing speed, poor real-time performance and accuracy of feature points extraction and matching in robot localization process, an improved SIFT hierarchical image matching algorithm was proposed based on color moment. Extreme point's detective range was extended, and the gradient directions and magnitude of feature points were calculated by using Sobel operator to improve SIFT performance; besides, the vector angle was taken as a criterion to measure SIFT features' similarity, thus the accuracy and speed of feature points extraction and matching were improved. In image matching process, image sequence was sorted by color moment, then the improved SIFT features were matched with these sorted images precisely. Experimental results show that the proposed algorithm is a real-time and robust method to mobile localization problem: compared with SIFT, the false matching rate of the proposed algorithm is lowered by 9.2%, and the number of feature points are reduced by 20%; hierarchical match improves the speed and accuracy of image matching, for the computation amount of SIFT features is reduced by 60% and the total time consume is reduced by 40%. ©, 2015, China Mechanical Engineering Magazine Office. All right reserved.


Zhu Q.,Yanshan University | Zhu Q.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Xia C.,Yanshan University | Chen W.,Yanshan University | And 2 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2015

Aiming at the particle degradation problem of an mobile robot FastSLAM a chaos optimization MPSO based algorithm was proposed. The algorithm incorporated the newest observation information into the prediction of particle, adjusted the proposal distribution of the particles, and the accuracy of prediction of a robot's position was enhanced. The MPSO was solved by a sequential two-step optimization strategy. Firstly, the speed of evolution of particle was improved by the median-oriented acceleration, the particle degradation effectively was overcome, the convergence of the algorithm was improved. Then, focusing on the depletion of the particle, the chaos search algorithm optimization algorithms was introduced to MPSO global optimal position to disperse gathered at local optimum particle swarm to the global optimum location close to broaden the scope of the solution space, thus maintaining the population the diversity of simulation. The experimental results prove that the improved method is correct and feasible. ©, 2015, China Mechanical Engineering Magazine Office. All right reserved.


Zhang Y.-J.,Yanshan University | Zhang Y.-J.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Liu W.-Z.,Yanshan University | Fu X.-H.,Yanshan University | And 3 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2016

Given that the traditional signal processing methods can not effectively distinguish the different vibration intrusion signal, a feature extraction and recognition method of the vibration information is proposed based on EMD-AWPP and HOSA-SVM, using for high precision signal recognition of distributed fiber optic intrusion detection system. When dealing with different types of vibration, the method firstly utilizes the adaptive wavelet processing algorithm based on empirical mode decomposition effect to reduce the abnormal value influence of sensing signal and improve the accuracy of signal feature extraction. Not only the low frequency part of the signal is decomposed, but also the high frequency part the details of the signal disposed better by time-frequency localization process. Secondly, it uses the bispectrum and bicoherence spectrum to accurately extract the feature vector which contains different types of intrusion vibration. Finally, based on the BPNN reference model, the recognition parameters of SVM after the implementation of the particle swarm optimization can distinguish signals of different intrusion vibration, which endows the identification model stronger adaptive and self-learning ability. It overcomes the shortcomings, such as easy to fall into local optimum. The simulation experiment results showed that this new method can effectively extract the feature vector of sensing information, eliminate the influence of random noise and reduce the effects of outliers for different types of invasion source. The predicted category identifies with the output category and the accurate rate of vibration identification can reach above 95%. So it is better than BPNN recognition algorithm and improves the accuracy of the information analysis effectively. © 2016, Peking University Press. All right reserved.


Zhang Y.-J.,Yanshan University | Zhang Y.-J.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Jia W.,Yanshan University | Fu X.-H.,Yanshan University | And 3 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2016

As to fitting the multi-peaks Brillouin scattering spectrum with traditional method, the maximum power point is usually selected as the benchmark while other extreme value points which are less than the maximum power are lost. The fitting curve only has one peak because the multi-peaks Brillouin scattering spectrum is simplified into the highest peak and several small peaks. So it will lead to the loss of useful information. In order to improve the feature extraction accuracy of Brillouin scattering spectrum, a hybrid optimization algorithm named MCDM-PSO-LM algorithm is presented based on MCDM and PSO-LM algorithm. The MCDM algorithm can identify and locate the peaks and valleys of multi-peaks Brillouin scattering spectrum accurately. The PSO-LM hybrid algorithm can realize the curve fitting on every peak and valley, and it can seach the center frequency shift of each peak. The PSO-LM hybrid algorithm can solves these disadvantages, which PSO algorithm premature convergence to local minimum and LM algorithm depends on the initial value problem. It can also combine the global search ability of PSO algorithm and the local search ability of LM algorithm. Compared with traditional algorithms, MCDM-PSO-LM algorithm can ensure the solving speed and accuracy to the optimal value, and the analytical solution will be close to the optimal value sufficiently. So it improves the operation ability. With different signal to noise ratio and linewidth, the results of frequency shift and temperature error show that the MCDM-PSO-LM method can locate every peak and valley of multi-peaks Brillouin scattering spectrum accurately. Thus, it can be used for the feature extraction of multi-peaks Brillouin scattering spectrum. The recognition effect of this method is obviously better than that of traditional algorithms and it can improve the accuracy of information analysis. © 2016, Peking University Press. All right reserved.


Fu X.,Yanshan University | Fu X.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Gao F.,Yanshan University | Fu G.,Yanshan University | And 3 more authors.
Optik | Year: 2015

A specialty optical taper is proposed for optical signal acquisition in fiber sensors, optical communication and laser radar etc. Based on the profile curve equation of specialty optical taper, the internal focus coupling efficiency has been analyzed by using the ray-tracing method. Considering the Fresnel reflection loss, the relationships among the internal focus depth, taper length, shape factor, large-end radius, small-end radius, radial displacement, and coupling efficiency are analyzed, respectively. The results show that the internal focus coupling efficiency can be close to 100% as a certain range of incidence angle varies in radial directions. Finally, the influencing factors of analysis conclusion are also given. © 2015 Elsevier GmbH.


Chen W.,Yanshan University | Chen W.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | Yu N.,Yanshan University | Yu N.,The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province | And 2 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2014

We propose a compact photonic crystal Mach-Zehnder interferometer index sensor with a two-dimensional rotated square lattice, based on the photonic crystal self-collimation effect. Using the same background index, the different index of the circular rods has different effective index. The line defected and the air slab waveguide are respectively used as the beam splitter and mirror of the interferometer, and a sensing area is setting on one arm of the interferometer. The index of the circular rods changes with the concentration of the solution filled into the sensing region, thereby affecting the center wavelength of the transmission spectrum, and establishing a mathematical relationship between the solution concentration and the transmission wavelength. Then we carry out a numerical simulation of the concentration measurement of the alcohol solution, the results show that the sensor sensitivity is 250 nm/RIU in the refractive index variation within the scope of 1.33-1.37.

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