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Youfu T.,Northeast Petroleum University | Longqing Z.,Northeast Petroleum University | Yong L.,Bohai Shipbuilding Heavy Industry Co.
Journal of Vibroengineering | Year: 2014

Vibration signal of reciprocating compressor gas valve presents a typical characteristics of non-stationarity and nonlinearity. An integration approach based on local mean decomposition (LMD) and Lempel-Ziv complexity (LZC) is proposed in this paper for improvement of diagnosis accuracy. First, the LMD method is applied to decompose original gas valve signals into a set of product functions (PFs), each of which is stationary signal. Then, the main PF components are selected by mutual information (MI) method with the original signal, and the LZC of each main PF is computed to form the feature vectors. Finally, the BP neural networks is applied to diagnose the faults of reciprocating compressor gas valve based on the feature vectors above. Experimental results indicate that the fault features of reciprocating compressor gas valve can be extracted by the integration of LMD and LZC. So the proposed approach is one of ways to achieve more accurate diagnosis of reciprocating compressor. © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. Source

Lei N.,Northeast Petroleum University | Tang Y.,Northeast Petroleum University | Lei Y.,Bohai Shipbuilding Heavy Industry Co.
Journal of Vibroengineering | Year: 2016

Vibration signal of reciprocating compressor gas valve represents nonlinear, non-stationary and multiple impulse characteristics. To extract the features of the signal, an integration approach based on local mean decomposition (LMD) method and autoregressive-generalized autoregressive conditional heteroscedasticity (AR-GARCH) model is proposed. First, the property of LMD is investigated in the paper, which indicates that LMD method not only can effectively alleviate non-stationary feature and restrain the end effect of non-stationary signal, but also can accurately improve the resolution of time-frequency analysis. Then, the first five PF components of gas valve signal are modeled by AR(1)-GARCH(1, 1) model as the feature vectors without any prior knowledge about the fault mechanism. Finally, the BP neural networks are applied to diagnose the faults of reciprocating compressor gas valve based on the feature vectors above. The results indicate that high diagnosis accuracy can be obtained by integrating LMD method and AR-GARCH model. So the approach proposed in the paper provides an effective measure to extract the fault feature of reciprocating compressor gas valve. © JVE INTERNATIONAL LTD. Source

Yang J.-Y.,Shenyang University of Technology | Liu J.-H.,Shenyang University of Technology | Qiu G.-L.,Shenyang University of Technology | Chen K.,Shenyang University of Technology | Wang D.-Y.,Bohai Shipbuilding Heavy Industry Co.
Shenyang Gongye Daxue Xuebao/Journal of Shenyang University of Technology | Year: 2012

In order to further improve the control precision of direct thrust control (DTC) system of permanent magnet linear synchronous motor (PMLSM), a control method based on predictive voltage modulation and Takagi-Sugeno (T-S) fuzzy strategy was proposed. The predictive voltage modulation technology was used to control the next periodic flux linkage, and the space vector pulse width modulation (SVPWM) technology was applied to approach the predictive voltage values. In addition, a T-S fuzzy controller was adopted to control both mover speed and electromagnetic thrust. The comparison and analysis on the simulation results in Matlab/Simulink environment reveal that the proposed DTC control system based on predictive voltage modulation and T-S fuzzy control strategy not only obviously reduces the electromagnetic thrust and flux linkage pulsation, but also exhibits the stronger robustness on the pulsation caused by nonlinear perturbations such as the time variation of motor parameters. Source

Chen Z.,Nuclear Power Institute of China | Liao L.-T.,Nuclear Power Institute of China | Liu L.-X.,Nuclear Power Institute of China | Li W.,Bohai Shipbuilding Heavy Industry Co.
Hedongli Gongcheng/Nuclear Power Engineering | Year: 2012

Considering the problems of small water inventory and inferior heat accumulation capacity of the secondary side of the once through steam generator(OTSG), and the need of rapid match of feedwater flowrate and the reactor power to ensure the steam quality, the T-S fuzzy neural method is incorporated into the OTSG feedwater control system to design a T-S fuzzy neural controller based on input and output data acquired by numerical simulation. The control results are verified by simulation method. The simulation results show that the control results under this control manner are better than those under the PID control manner and meet the control requirements satisfactorily. Source

Zhang Y.,China Institute for Radiation Protection | Yang Y.,Bohai Shipbuilding Heavy Industry Co.
Hedianzixue Yu Tance Jishu/Nuclear Electronics and Detection Technology | Year: 2011

Proportional counter can be used as low-energy particles detector because of its gas gain. According to charging manner, proportional counter can be divided into sealed and gas-flow proportional counters. Compared with gas-flow counter, although sealed proportional counter can be operated simply but it is short-lived, needs to replace the sealed gas periodically. It introduces the aging phenomenon of sealed proportional counter and a method for optimising the gas replacing period. Source

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