North Western Polytechnical University of China

Xian, China

North Western Polytechnical University of China

Xian, China
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Wang H.,German Aerospace Center | Wang H.,North Western Polytechnical University of China | Herlach D.M.,German Aerospace Center | Liu R.P.,Yanshan University
EPL | Year: 2014

Liquid Cu50Zr50 glass-forming alloy is undercooled by electrostatic levitation up to 311 K below its melting temperature. The dendrite growth velocity is measured as a function of undercooling. A maximum in the velocity-undercooling relation is observed. It is analysed within the dendrite growth theory. The investigations give evidence of a transition from thermally controlled growth at small undercoolings to diffusion-controlled growth at large undercoolings. In the regime where the kinetic interface undercooling dominates, activation energy is determined which is comparable to the activation energy of atomic diffusion. At largest undercoolings deviations from the Arrhenius-like behaviour appear which indicate cooperative atomic diffusion in the temperature range above the glass temperature. © Copyright EPLA, 2014.


Ismail M.,Beihang University | Yihua C.,Beihang University | Bakar A.,North Western Polytechnical University of China | Wu Z.,Beihang University
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering | Year: 2014

Heavy rainfall greatly affects the aerodynamic performance of the aircraft. Aerodynamic efficiency degradation due to the heavy rain has been the cause of many aircraft accidents. We have studied the effects of heavy rain on the aerodynamic efficiency of NACA 0012 2D airfoil cruise and landing configurations and NACA 0012 3D rectangular wing. Our results show significant increase in drag and decrease in lift in heavy rain environment. For our study we used preprocessing software gridgen for creation of geometry and mesh and fluent as solver. Discrete phase modeling has been used to model the rain particles using two-phase flow approach. The rain particles have been assumed to be inert. In simulated rain environment, both the 2D airfoil and 3D wing showed significant decrease in lift and increase in drag. This study will be quite useful for the designer of the commercial aircrafts and unmanned aerial vehicles and will be helpful for training of the pilots to control the airplanes better in heavy rain environment. © IMechE 2013 Reprints and permissions: sagepub.co.uk/ journalsPermissions.nav.


Wu H.-X.,North Western Polytechnical University of China | Kang F.-J.,North Western Polytechnical University of China | Huang W.,PLA Air Force Aviation University | Lu Y.,PLA Air Force Aviation University
Xitong Fangzhen Xuebao / Journal of System Simulation | Year: 2012

A software simulation method based on virtual reality was proposed to simulate the display and control system of an aircraft in three-dimensional environment. Virtual panels were applied to create main man-machine interfaces; Vega Prime virtual reality development environment and dynamic texture technology based on OpenGL were used to produce three-dimensional scenes and animations; and multi-threading technology was adopted to improve the real-time performance of software. The result of simulation proves this method can fulfill anticipated functions and meet the requirement for the real-time performance. © copyright.


Zhan T.,North Western Polytechnical University of China | Liao Z.G.,IBM | Gao L.,North Western Polytechnical University of China
Advanced Materials Research | Year: 2014

Computer Thinking is the core content of Computer Basic knowledge. With the full implementation of quality education in order to cultivate the innovative spirit and practical ability, computer thinking knowledge and skills are necessary for current college students. Aimed at the, the paper puts forward Visualization teaching methods and use typical cases in teaching experience of College Computer Foundation, which will help students have access to professional knowledge and skills about computer science. © (2014) Trans Tech Publications, Switzerland.


Jiang W.,North Western Polytechnical University of China | Chai H.,North Western Polytechnical University of China
IEEE International Conference on Industrial Engineering and Engineering Management | Year: 2016

R&D Project risks are not always independent, yet currently dependencies between risks have not been managed by risk management practices clearly. If risks with multiple fronts can be identified and analyzed explicitly by a scientific risk management method, it will be developed for better risk management strategies and more effective risk planning decisions. We propose a management methodology with factor analysis and AHP to set up project risk evaluation index system. Through fuzzy comprehensive evaluation method, it could be confirmed that risk factors do exist in R&D projects in full life time and can be identified, evaluated and managed systematically in GD. To deal with risk issues, communications between knowledge management system and risk management team should be built in the entire risk management in R&D in full life time. © 2015 IEEE.


Xu G.,Xi'an Technological University | Gu Z.,North Western Polytechnical University of China | Wei S.-M.,Xi'an Technological University
Gongneng Cailiao yu Qijian Xuebao/Journal of Functional Materials and Devices | Year: 2012

In order to improve the orientated growth of HgI2 films in vapor, iso-epitaxy layers of poly-crystalline mercuric iodide were deposited on ITO conductive glass by DSMO-HgI2-H2O solvent evaporation, polycrystalline HgI2 films were then grown on iso-epitaxy layers by PVD. The films grew were investigated by SEM and XRD. The polycrystalline HgI2 films detectors fabricated was studied by an un-collimated 241Am radiative source with the principal energy of 59.5keV at room temperature.


Bakar A.,North Western Polytechnical University of China | Ke-Shi Z.,North Western Polytechnical University of China
Proceedings of 2013 10th International Bhurban Conference on Applied Sciences and Technology, IBCAST 2013 | Year: 2013

This paper presents the importance of multidisciplinary optimization and its promising results. Evolutionary algorithm is applied which takes into account the aerodynamics and structure of transonic wing. Some classical and widely accepted principles are applied to predict the performance of the wing. Aerodynamic module calculates the induced drag of the wing using multiple lifting line theory. The friction/form drag is calculated by wetted area and using the prediction of skin friction models and form-factor estimation. Total drag is then calculated by summing the induced drag, friction drag and the wave drag, from Korn equation. To estimate the bending material weight, wing is modeled as double-plate wing box. Trade-off between minimum drag and minimum weight is studied. The dependency of the design space on specific wing parameters has also been studied. A significant improvement in the performance of a transonic transport aircraft wing can be achieved using the multidisciplinary optimization technique. © 2013 IEEE.


Xu G.,Xi'an Technological University | Gu Z.,North Western Polytechnical University of China | Wei S.,Xi'an Technological University
Bandaoti Guangdian/Semiconductor Optoelectronics | Year: 2013

In order to improve the orientated growth of HgI2 films in vapor, iso-epitaxy layers of polycrystalline mercuric iodide were deposited on ITO conductive glass by acetone-HgI2-H2O solvent with different concentrations. Polycrystalline HgI2 films were then grown on better orientation iso-epitaxy layers by PVD. The grown films were investigated by SEM and XRD. The efficiency of the detectors was studied by using uncollimated 137Cs as the radiative source with the principle energy of 662 keV at room temperature.


Deng L.,North Western Polytechnical University of China | Fan Y.,North Western Polytechnical University of China
Guangxue Xuebao/Acta Optica Sinica | Year: 2015

By the means of three-dimension ray tracing method, the channel impulse response under the nonempty indoor visible light transmission environment and the root-mean-square (RMS) delay spread when light source locates in different positions of the ceiling are estimated. Based on this, the finite state Markov chain is used to model the indoor visible light fading channel, and the distribution of the non-empty indoor visible light channel impulse response is obtained. The results demonstrate that random distribution reflector imposes greater effects on the channel impulse response in the non- line of sight (NLOS) transmission environment than that in the line of sight (LOS) situation. Besides, the RMS delay spread is obvious when the light source locates at the corner of the ceiling instead of other positions, which means that the multipath effect is more obvious at this place. ©, 2015, Chinese Optical Society. All right reserved.


Li S.,North Western Polytechnical University of China | Zhang Z.,North Western Polytechnical University of China | Duan J.,North Western Polytechnical University of China
International Arab Journal of Information Technology | Year: 2014

In multi-label classification, feature selection is able to remove redundant and irrelevant features, which makes the classifiers faster and improves the prediction performance of the classifiers. Currently, most of feature selection algorithms in multi-label classification are dependent on the concrete classifier, which leads to high computation complexity. Hence this paper proposes an Ensemble Multi-label Feature Selection algorithm based on Information Entropy (EMFSIE), which is independent on any concrete classifiers. Its core idea consists of: Employing the information gain to evaluate the correlation between the feature and the label set, and filtering out useful features more effectively. We calculate the information gain in an ensemble framework and filter out useful features according to the threshold value determined by the effective factor. We validate EMFSIE on four datasets from two domains using four different multi-label classifiers. The experimental results and their analysis show preliminarily that EMFSIE can not only remove more than 70% of original features, which makes the classifiers faster, but also keep the prediction performance of the classifiers as good as before, even enhance the prediction performance on three datasets underthe two-tailed paired t-tests at 0.05 significance level.

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