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Weak signal detection based on combination of power and exponential function model in tri-stable stochastic resonance
ZHANG Gang, GAO Junpeng
Journal of Computer Applications    2018, 38 (9): 2747-2752.   DOI: 10.11772/j.issn.1001-9081.2018010192
Abstract525)      PDF (902KB)(309)       Save
Under the background of strong noise, it is difficult to detect and extract weak signals. To solve the above problems, a new combination model of power and exponential function in tri-stable system was proposed based on the classic bistable system model and the Gaussian Potential model. First of all, the tri-stable system model was constructed by combining power function and exponential function, then the stochastic resonance was generated by adjusting related parameters, which was validated by numerical simulations. Secondly, using the average Signal-to-Noise Ratio (SNR) of output as a measure index, the artificial fish swarm intelligence algorithm was used to optimize the corresponding parameters, which makes the tri-stable system combining the power function and the exponential function achieve the maximum output SNR, and the phenomenon stochastic resonance was generated. Finally, it was applied to the diagnosis of bearing faults. At the same condition that the output SNR is -25.8 dB, the output SNR of the bistable system and tri-stable system combining the power function and the exponential function is -13.1 dB and -8.59 dB respectively. Simulation results demonstrate that the performance of the proposed system is better than the bistable system, and it is effective in weak signal detection and extraction.
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Recognition of temporal relation in Chinese electronic medical records
SUN Jian, GAO Daqi, RUAN Tong, YIN Yichao, GAO Ju, WANG Qi
Journal of Computer Applications    2018, 38 (3): 626-632.   DOI: 10.11772/j.issn.1001-9081.2017082087
Abstract642)      PDF (1121KB)(735)       Save
The temporal relation or temporal links (denoted by the TLink tag) in Chinese electronic medical records includes temporal relations within a sentence (hereafter referred to as "within-sentence TLinks"), and between-sentence TLinks. Among them, within-sentence TLinks include event/event TLinks and event/time TLinks, and between-sentence TLinks include event/event TLinks. The recognition of temporal relation in Chinese electronic medical record was transformed into classification problem on entity pairs. Heuristic rules with high accuracy were developed and two different classifiers with basic features, phrase syntax, dependency features, and other features were trained to determine within-sentence TLinks. Apart from heuristic rules with high accuracy, basic features, phrase syntax, and other features were used to train the classifiers to determine between-sentence TLinks. The experimental results show that Support Vector Machine (SVM), SVM and Random Forest (RF) algorithms achieve the best performance of recognition on within-sentence event/event TLinks, within-sentence event/time TLinks and between-sentence event/event TLinks, with F 1-scores of 84.0%, 85.6% and 63.5% respectively.
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Processing method of INS/GPS information delay based on factor graph algorithm
GAO Junqiang, TANG Xiaqing, ZHANG Huan, GUO Libin
Journal of Computer Applications    2018, 38 (11): 3342-3347.   DOI: 10.11772/j.issn.1001-9081.2018040814
Abstract902)      PDF (963KB)(612)       Save
Aiming at the problem of the poor real-time performance of Inertial Navigation System (INS)/Global Positioning System (GPS) integrated navigation system caused by GPS information delay, a processing method which takes advantage of dealing with various asynchronous measurements at an information fusion time in factor graph algorithm was proposed. Before the system received GPS information, the factor nodes of the INS information were added to the factor graph model, and the integrated navigation results were obtained by incremental inference to ensure the real-time performance of the system. After the system received the GPS information, the factor nodes about the GPS information were added to the factor graph model to correct the INS error, thereby ensuring high-precision operation of the system for a long time. The simulation results show that, the navigation state that has just been updated by GPS information can correct the INS error effectively, when the correction effect of real-time navigation state on INS error becomes worse, as the time of GPS information delay becomes longer. The factor graph algorithm avoids the adverse effects of GPS information delay on the real-time performance of INS/GPS integrated navigation system, and ensures the accuracy of the system.
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Finite-time adaptive chaos control for permanent magnet synchronous motor
GAO Junshan, SHI Lanlan, DENG Liwei
Journal of Computer Applications    2017, 37 (2): 597-601.   DOI: 10.11772/j.issn.1001-9081.2017.02.0597
Abstract606)      PDF (776KB)(503)       Save
Aiming at the issue that chaotic attractor exists in Permanent Magnet Synchronous Motor (PMSM) and chaotic synchronous control of PMSM cannot be realized except on the cycle of the equilibrium point, a kind of zero error system algorithm based on automatic control theory and finite time control principle was proposed. Firstly, the error system was established by mathematical model of PMSM and a mathematical formula between each state variable and its expected value in PMSM. Secondly, synchronous controller and correction rate were designed for the error system model and the conclusion that the error system could quickly converge to zero in finite time was proved by using Lyapunov's stability criterion. Finally, interference was imposed on the error system and the robustness of the algorithm was analyzed. The theoretical analysis and simulation results show that the proposed algorithm can maitain in zero balance after reaching the zero point of the system, which can effectively restrain the chaotic attractor and adjust the input and output of PMSM flexibly; and the PMSM system has good robustness to the uncertainty parameter and external disturbance while ensuring the normal operation of PMSM.
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Automatic hyponymy extracting method based on symptom components
WANG Ting, WANG Qi, HUANG Yueqi, YIN Yichao, GAO Ju
Journal of Computer Applications    2017, 37 (10): 2999-3005.   DOI: 10.11772/j.issn.1001-9081.2017.10.2999
Abstract523)      PDF (1095KB)(518)       Save
Since the hyponymy between symptoms has strong structural features, an automatic hyponymy extracting method based on symptom components was proposed. Firstly, it was found that symptoms can be divided into eight parts: atomic symptoms, adjunct words, and so on, and the composition of these parts satisfied certain constructed rules. Then, the lexical analysis system and Conditional Random Field (CRF) model were used to segment symptoms and label the parts of speech. Finally, the hyponymy extraction was considered as a classification problem. Symptom constitution features, dictionary features and general features were selected as the features of different classification algorithms to train the models. The relationship between symptoms were divided into hyponymy and non-hyponymy. The experimental results show that when these features are selected simultaneously, precision, recall and F1-measure of Support Vector Machine (SVM) are up to 82.68%, 82.13% and 82.40%, respectively. On this basis, by using the above hyponymy extracting algorithm, 20619 hyponymies were extracted, and the knowledge base of symptom hyponymy was built.
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Strong scattering objects segmentation based on graph cut and Mean Shift algorithm from SAR images
LYU Qian GAO Jun GAO Xin
Journal of Computer Applications    2014, 34 (7): 2018-2022.   DOI: 10.11772/j.issn.1001-9081.2014.07.2018
Abstract185)      PDF (807KB)(372)       Save

Aiming at the characteristics of Synthetic Aperture Radar (SAR) images and the problem of the standard graph cut segmentation algorithm's high computational complexity, a method of strong scattering objects segmentation based on graph cut and Mean Shift algorithm was proposed. Firstly, the image was pre-processed with the Mean Shift algorithm to produce over-segmentation areas. Then, a graph was built with nodes responding to over-segmentation areas, and then the results of SAR strong scattering targets segmentation were obtained by using graph cut algorithm. Compared with nodes responding to pixels in the standard graph cut algorithm, the number of nodes and edges in the graph were reduced by two orders of magnitude and the computational efficiency was significantly improved. Furthermore, according to the strong scattering characteristics of the targets in SAR images, the “object” terminal and the “background” terminal were defined automatically to reduce human interaction. The experiments show that the proposed method combines the advantages of Mean Shift and graph cut effectively, and it can effectively extract SAR strong scattering targets from the background clutter.

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Multi-objective particle swarm optimization method with balanced diversity and convergence
GENG Huantong GAO Jun JIA Tingting WU Zhengxue
Journal of Computer Applications    2013, 33 (07): 1926-1929.   DOI: 10.11772/j.issn.1001-9081.2013.07.1926
Abstract891)      PDF (724KB)(543)       Save
Particle Swarm Optimization (PSO) algorithm is population-based and it is effective for multi-objective optimization problems. For the convergence of the swarm makes the classical algorithm easily converge to local pareto front, the convergence and diversity of the solution are not satisfactory. This paper proposed an independent dynamic inertia weights method for multi-objective particle swarm optimization (DWMOPSO). It changed each particle's inertia weight according to the evolution speed which was calculated by the value of each particle's best fitness in the history. It improved the probability to escape from the local optima. In comparison with Coello's MOPSO through five standard test functions, the solution of the new algorithm has great improvement both in the convergence to the true Pareto front and diversity.
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Implementing a Linux-based Java graphic platform on smart phone
GAO Juan,FU Cheng,YOU Jin-yuan
Journal of Computer Applications    2005, 25 (11): 2712-2714.  
Abstract1523)      PDF (566KB)(1415)       Save
The requirements to hardware and software of smart phones are comparatively high.In the software aspect,it needs a GUI platform that can support Java programs at least.QT/Embedded is a very good embedded GUI that supports Java programs for smart phones.The implementation of the Java graphic platform on smart phone was introduced.
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