Nanjing Engineering Institute of Aircraft Systems

Nanjing, China

Nanjing Engineering Institute of Aircraft Systems

Nanjing, China
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Cao Y.,Northwestern Polytechnical University | Wang J.,Northwestern Polytechnical University | Yu Y.,Nanjing Engineering Institute of Aircraft Systems | Xie R.,Northwestern Polytechnical University | Wang X.,Northwestern Polytechnical University
CGNCC 2016 - 2016 IEEE Chinese Guidance, Navigation and Control Conference | Year: 2016

This paper deals with the problem of fault prediction and failure prognosis for electro-mechanical actuators. Firstly, traditional C-C method to reconstruct phase space of time series is developed and searching radius is expanded to determine the optimal delay time and embedded dimension. Then support vector regression (SVR) is utilized on fault prediction and failure prognosis. With the large size of sample data taken into account, the improved sequential minimal optimization (ISMO) algorithm is employed to solve the SVR model. And to raise the training speed, the duality gap ratio is introduced to improve the stopping criteria for iterations. The highlight is that real experimental data from NASA Prognostics Center are used to train and test the prediction model. Finally comparing with the BP network method, the simulation result demonstrates that the ISMO-SVR method has characteristics of high prediction accuracy and time efficiency, all of which will help take preventive measures before failure occurs. © 2016 IEEE.


Li T.,Northwestern Polytechnical University | Yu Y.,Nanjing Engineering Institute of Aircraft Systems | Wang J.,Northwestern Polytechnical University
CGNCC 2016 - 2016 IEEE Chinese Guidance, Navigation and Control Conference | Year: 2016

In this paper, a novel fault diagnosis method based on quantum particle swarm optimization (QPSO) and least square support vector regression (LSSVR) algorithm, was proposed to detect sensor faults for electro-hydraulic actuators. Prediction model based on LSSVR algorithm is established to forecast sensor output. By calculating the residual between the forecast output of the LSSVR model and the actual output of the sensor, a fault can be indicated. Furthermore, to improve the prediction accuracy of the LSSVR model, QPSO is employed to optimize the hyper-parameters used in the LSSVR model. Simulation experiments show that, compared with PSO-LSSVR, the prediction error of QPSO-LSSVR is smaller and the convergence rate is faster. The effectiveness of the fault diagnosis method for detecting several typical sensor faults, which occurred in the actuator system, is also verified in the simulation experiments. © 2016 IEEE.


Wang Z.,Nanjing Engineering Institute of Aircraft Systems
30th Congress of the International Council of the Aeronautical Sciences, ICAS 2016 | Year: 2016

Approved by Civil Aviation Administration of China (CAAC), proposal of Master Minimum Equipment List (MMEL) is prepared by aircraft manufacturers to permit aircrafts under conditions that some equipment or its function is not available. Effective MMEL can balance the security and profitability of aircraft, which means in premise of security aircraft will maximize the benefits. Aiming to keep dispatch reliability, MMEL is taken into account in all stages of aircraft design and combined with aircraft safety analysis and evaluation process. In design phase, we will make specific components of aircraft more reliable and safer. At the same time, reasonable operating and maintenance procedures are essential to lay down a high reliability MMEL, form aspect of effect of dispatch reliability on operation.


Zhang M.,Hubei Engineering University | Zhang M.,Hubei Key Laboratory of Waterjet Theory and New Technology | Kang Y.,Hubei Engineering University | Kang Y.,Hubei Key Laboratory of Waterjet Theory and New Technology | And 5 more authors.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2017

A self-excited water-air jet was generated by the sucked air through four holes through the wall of a resonance chamber in front of a jet nozzle. Experiments were performed on this kind of jet to identify effects of inspiratory modes and diameters of suction holes on the self-excited inspiratory jet by examining erosion depth and damaged area in specimens and inspiratory capacity through the holes. The results show that the erosion depth and damaged area increased with increasing diameter of the suction holes, and the erosion depth increased with the number of holes. Inspiratory modes play an important role in the erosion morphology of specimen and the unique erosion characteristics are observed when air is introduced. Additionally, the damaged area under the asymmetric inlet condition is significantly higher than that under the symmetric inlet condition. The inspiratory flow is periodic, and the inspiratory capacity increased with increasing inlet pressure. The inspiratory modes and the diameter of suction hole affect the inspiratory performance. Particularly, the inspiratory capacity increase with increasing diameter of the suction holes when only one suction hole is in operation, while the best inspi-ratory performance is achieved at 4 mm diameter when multiple suction holes are open. © 2017, Editorial Department of Journal of Drainage and Irrigation Machinery Engineering. All right reserved.


Lan X.,Tsinghua University | Pan C.,Nanjing Engineering Institute of Aircraft Systems | Zhou M.,Tsinghua University
Qinghua Daxue Xuebao/Journal of Tsinghua University | Year: 2016

The design of a combustion chamber must match the intake air and fuel injection systems to improve the power, specific fuel consumption (SFC) and emissions of diesel engines. Numerical simulations and experimental validations are used to optimize the combustion chamber of an electrically controlled, single-cylinder diesel engine. The power and torque of a single-cylinder diesel engine are predicted using a hybrid Euler-Lagrange method with comparisons to test measurements. A parameterized design is then used to design the combustion chamber. Three key parameters for the re-entrance ratio, depth and inner diameter of the combustion chamber relate to the engine performance (power, torque, SFC and emission). The results show that the hybrid Euler-Lagrange method can be used to design the combustion chamber. The three key parameters strongly affect the engine performance for the given intake air and fuel injection systems. © 2016, Tsinghua University Press. All right reserved.


Li J.,PLA Air Force Aviation University | Li J.,Ludong University | Jing B.,PLA Air Force Aviation University | Qiang X.,PLA Air Force Aviation University | And 2 more authors.
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

The health state of airborne fuel pumps is important for the achievement and safety of flight mission, so the fault state feature extraction and diagnosis for the fuel pumps become an urgent problem. Through the analysis of the output signal about the vibration sensors and pressure sensor from the experiment system of airborne fuel pump, a sample quantile based fault state feature extraction method is presented. Firstly, by the asymptotic distribution theorem of the quantile, the statistic character of the sample quantile is discussed; the correspondence between the fault state and the sample quantile is discussed; the feasibility of the presented method is ensured in theory; statistic analysis has been done for the real data, and the stability alone with the sample size is discussed. Secondly, the confidence interval of sample quantile is computed based on the asymptotic distribution theorem, and compared with that obtained by the Bootstrap methods. The results show that the confidence interval of sample quantile obtained according to the asymptotic distribution theorem is credible, providing basis for online fault diagnosis. Then the Bayesian discriminant function is established based on the quantile feature vector extracted under different states, which will be used for the fault diagnosis. Finally, the layout of the sensors is optimized based on the accuracy of fault diagnosis. The results show that the vibration sensors combined with pressure sensor will improve the accuracy of fault diagnosis, and only one vibration sensor combined with one pressure sensor can finish the fault diagnosis completely. This study provides theoretical support for the quick and accurate online decision about the states of the fuel pump, and it can reduce volume, power consumption and complexity of the system in engineering applications. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.


Chen Y.Z.,Nanjing Institute of Technology | Gong D.P.,Nanjing Engineering Institute of Aircraft Systems
Advanced Materials Research | Year: 2013

Use Gambit and Fluent to the servo valve armature component of squeak problem undertook CFD is analyzed, simulates the flow field distribution in internal circuit structure, found in the servo valve armature component whistle when fluid in the inner of the product, produced a marked a negative pressure zone, and in this context the armature assembly stress sharply change, causing the armature assembly vibration squeal, changing the internal structure of the product again CFD simulation, negative pressure area disappeared, the pressure change tends to be steady, the structure of the product was the actual through pressure liquid servo valve test, howling problem solved. © (2013) Trans Tech Publications, Switzerland.


Tian L.,Nanjing University of Aeronautics and Astronautics | Fu Y.,Nanjing University of Aeronautics and Astronautics | Yang L.,Nanjing University of Aeronautics and Astronautics | Xu J.,Nanjing University of Aeronautics and Astronautics | And 3 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2013

In order to investigate the influence law of chip formation process affected by grinding speed, the single-grain tests are carried out on the difficult to cut materials superalloy GH4169. The single-grain grinding forces are measured. The trances and chips morphologys of the single-grain grinding tests are observed and analyzed to calculate the critical thickness of chips formation. The speed effect on the grinding process scratches and grinding forces are studied systematically in the grinding wheel velocity range 20 m/s to 165 m/s. The results show that the grinding speed affects the division of grinding process and the critical thickness of chip formation, and the single-grain grinding forces first increase then decrease and increase finally with the increasing grinding velocity. Machinability changes due to the speed effect, and these changes caused by the alternative variation of the leading position between the strain rate strengthening effects and the thermal softening effects on the difficult to cut materials. Serrated chip occurs during single-grain grinding superalloy, as the grinding speed increases, the grade of serrated tooth grows and the pile up rate of the single-grain grinding grooves decrease first then increases, these phenomenon indicated that mechanism of chip formation due to the speed effect. © 2013 Journal of Mechanical Engineering.


Huang J.,Nanjing University of Aeronautics and Astronautics | Chen Q.,Nanjing University of Aeronautics and Astronautics | Chen W.,Nanjing University of Aeronautics and Astronautics | Ren X.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2014

Wireless power transmission region stands out for its convenience in the applications where several terminals or movable terminals need to be charged. The conventional single coil excited charging region has the drawback of distance and angle limitation. To overcome the shortcoming, a charging region which is constructed by four emitting coils is proposed in this paper. This four emitting coils configuration can not only increase the transmission distance but also weaken the sensitivity to angle change. Regarding the emitting coil as magnetic pole, four windings connection types of these four emitting coils are put forward. By both theoretical analysis and software simulation, magnetic field distributions of these four windings connection types are studied and the S-S-N-N is finally selected as the windings connection type. The equivalent circuit for this configuration is derived and the parameter design method is further presented. Finally, a 0.8×0.8×0.8m3 wireless power transmission region with four emitting coils via magnetic resonances is fabricated in the lab and the experimental results can verify the correctness of parameters design and the effectiveness of the proposed four coils excited charging region. © 2014 IEEE.


Zhang Z.,Nanjing University of Aeronautics and Astronautics | Xu D.,Nanjing Engineering Institute of Aircraft Systems | Xu P.,Nanjing University of Aeronautics and Astronautics
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

A new current source driver (CSD) was proposed for a synchronous Buck converter. The proposed CSD can drive two MOSFETs independently with different drive currents for optimal design. For the control MOSFET, the optimal design involves a tradeoff between the switching loss reduction and drive circuit loss, while for the Synchronous Rectifier (SR) MOSFET, the optimal design involves a tradeoff between body diode conduction loss, and drive circuit loss. The improved CSD using integrated inductors was also presented to reduce the number of magnetic cores and the core loss. The experimental results verify the advantages of the CSD. © 2011 Chin. Soc. for Elec. Eng.

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