Northern University for Nationalities

Yinchuan, China

Northern University for Nationalities

Yinchuan, China
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Pei Z.,Hebei University of Engineering | Du J.,Northern University for Nationalities | Gao X.,Hebei University of Engineering | Lei Y.,Peking University | Li P.,Hebei University of Engineering
Journal of Nanoscience and Nanotechnology | Year: 2014

Three porous structures of ZnO were successfully synthesized in mixed solvents of ethylene glycol and distilled water. By adjusting ratios of ethylene glycol and distilled water, ZnO morphologies changed. Small porous plates with different sizes, folded porous plates with well-proportioned pores, heavily folded porous plates and solid flowers without pores emerged in sequence. The mechanism of the synthetic process was discussed. The morphologies and microstructures were investigated by transmission electron microscopy (TEM). The phase composition was verified by X-ray diffraction (XRD). This synthetic route provides a new idea to prepare other new structure materials. Copyright © 2014 American Scientific Publishers.


Wang J.-G.,Yunnan Agricultural University | Gao Q.-C.,China University of Mining and Technology | Lu H.,Northern University for Nationalities | Liang S.-F.,China University of Mining and Technology | And 2 more authors.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015

Using SHPB test device, a test method used in layered medium dynamic performance study and data analysis was established. By adjusting bullet speeds and testing repeatedly, the varyings of stress and strain of hard-soft layered medium composed of C30 concrete and foam concrete versus time under impact loading were measured. The test results showed that the plastic property of the hard-soft layered medium is much stronger than that of hard material; the elastic modulus of the hard-soft layered medium decreases gradually with increase in stress and strain, the energy absorption action of soft material can effectively protect hard material, so the hard-soft layered medium has a good ability of anti-high speed shock and anti-shock wave propagation. ©, 2015, Chinese Vibration Engineering Society. All right reserved.


Pei Z.,Hebei University of Engineering | Du J.,Northern University for Nationalities | Gao X.,Hebei University of Engineering
Journal of Nanoscience and Nanotechnology | Year: 2014

0.6 to 7.5 μm LiMnPO4 porous plates with pore sizes from 100 to 150 nm were successfully synthesized in mixed solvents of ethylene glycol and distilled water. By changing stirring time, different morphologies of LiMnPO4 were prepared. Porous plates with the percentages of more than 70%, more than 50% and 25% porous ones were formed in sequence. The according rest parts were particles, less than 40% solid plates and 25% solid ones, respectively. Stirring time is the key cause influencing the nucleation rate and diffusion rate of the initial formed growth units of LiMnPO 4. Through adjusting the factor, chemicals with specific morphology can be obtained in mixed solvents. The phase composition and microstructure were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. This synthetic route provides us a new idea to prepare new structure materials. Copyright © 2014 American Scientific Publishers.


Wang T.,Northern University for Nationalities | Tian Z.-F.,Fudan University | Ge Y.-B.,Ningxia University
Shuidonglixue Yanjiu yu Jinzhan/Chinese Journal of Hydrodynamics Ser. A | Year: 2011

A high order compact upwind scheme was developed for solving convection diffusion equation with source term. The schemewas applied to solve the governing equations that describe binary fluid mixtures convection systems. The convection terms were discretized with fourth order compact upwind finite difference schemes and the viscous terms were discretized with fourth order accurate symmetrical compact finite difference schemes. Numerical simulations of the traveling wave convection patterns in fluid mixtures inside a large rectangular chamber with an aspect ratio Γ=46 were performed. Counter-propagating waves and two types of modulated traveling wave were obtained. The results are in good agreement with those obtained by other scholars, which proves the validity of the present method. Besides, extend traveling waves were obtained by further computation. Based on above, the dependence of the localized traveling wave on Rayleigh number and the stability of localized traveling wave exists with the range of r=1.12-1.22 were discussed.


Chen Y.-X.,Ningxia University | Gao Y.-L.,Ningxia University | Gao Y.-L.,Northern University for Nationalities | Ma W.-L.,Northern University for Nationalities
Fangzhi Gaoxiao Jichukexue Xuebao | Year: 2014

For a kind of linear fractional programming problems, a new branch and bound algorithm is proposed. The main features of this algorithm is that by utilizing the monotonicity and bump of the logarithmic function and the exponential function , a relaxation linear programming problem of equivalent problem of original problem is established, and a new second-relaxation linear programming is put forward to determine the lower bound of the optimal value of the original problem . This can be used to improve the convergence rate of the algorithm. Through the successive refinement of the linear relaxation of the feasible region and the solutions of a series of relaxation linear programming problems, it shows that the proposed branch and bound algorithm is convergent to the global minimum from theory. And finally the numerical experiments are reported to show the feasibility of the proposed algorithm.


Du J.H.,Northwestern Polytechnical University | Du J.H.,Northern University for Nationalities | Yang Q.F.,Northwestern Polytechnical University | Fan X.D.,Northwestern Polytechnical University
Advanced Materials Research | Year: 2011

Poly (3-hydroxybutyrate) (PHB)/poly (L-lactide) (PLLA)/poly (ethylene-oxide) (PEO) composite Ultrafine Fibers were prepared by solution dry spinning technique. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to characterize the PHB/PLLA/PEO composite Ultra-fine fibers. In all of the spinning conditions investigated, the average diameter of the as-spun PHB/PLLA/PEO fibers was 2.1 μm and increased with increasing the mass ratio of PHB/PLLA. The degree of crystallinity of as-spun PHB/PLLA/PEO fibers increased with increasing PHB content in their blends, and the α-form crystals of PHB and PLLA in as-spun fibers were obtained. When the mass ration of PHB/PLLA in as-spun PHB/PLLA/PEO fibers was 3:1,the structure of as-spun fibers was the skin-core, which PHB formed core of fibers and PLLA form skin of fibers; when the mass ration of PHB/PLLA in as-spun PHB/PLLA/PEO fibers was 1:1, PLLA and PEO were embedded into PHB phase by droplet and febrile morphology to form matrix-fibril structure of as-spun PHB/PLLA/PEO fibers. © (2011) Trans Tech Publications, Switzerland.


Qian Y.,Northern University for Nationalities
2010 International Conference on Multimedia Technology, ICMT 2010 | Year: 2010

this paper presents an improved threshold function in order to improve the effect of electro-cardio signal denoising. This improved threshold function is continuous; the wavelet coefficients are reduced to zero smoothly according to the function when their absolute values are less than threshold value. Adding a factor to the function can change the form of threshold function and adjust the estimated deviation of wavelet coefficients. The results of MATLAB simulation show that the denoising effect of this method is better than soft and hard threshold. It may help to improve the quality of diagnosis if this method is applied to electro-cardio signal pre-processing, and it can be applied in communication systems for speech signal denoising. ©2010 IEEE.


Zhao T.,Northern University for Nationalities | Ma S.,Northern University for Nationalities
Proceedings - 2010 International Workshop on Chaos-Fractal Theories and Applications, IWCFTA 2010 | Year: 2010

The modified projective synchronization problem is concerned in a non-autonomous oscillating circuit with random parameter. At first, the oscillating circuit is transformed into its equivalent deterministic nonlinear one by the Chebyshev polynomial approximation. Suitable controllers and adaptive laws of parameters are given to make the two systems achieve synchronization. Numerical results show the effectiveness of this method. © 2010 IEEE.


Ma S.,Northern University for Nationalities | Tingting Z.,Northern University for Nationalities
Proceedings - 2010 International Workshop on Chaos-Fractal Theories and Applications, IWCFTA 2010 | Year: 2010

The proportional plus-derivative control of chaotic system is concerned. Controller is firstly designed and then the controlled stochastic forced brusselator is transformed into its equivalent deterministic one by the Chebyshev polynomial approximation. Finally, the chaotic motions of forced brusselator can be successfully converted to the stable lower periodic orbits by proportional plus-derivative method. The numerical results of this paper show the effectiveness of this method. © 2010 IEEE.


Du J.H.,Northern University For Nationalities | Ren L.Y.,Northern University For Nationalities | Zhang B.,Northern University For Nationalities
Advanced Materials Research | Year: 2013

Poly (3-hydroxybutyrate) (PHB)/poly (L-lactide) (PLLA)/nano-hydroxyapatite (n-HA) composite Ultrafine Fibers with diameter of 610 ~ 830 nm were prepared by electro-spinning. The surface morphology was studied by scanning electron microscopy (SEM). The effect of the process of prepareing spinning solutions, the constituent of spinning solutions, the concentration of PHB/PLLA/ n-HA blends spinning solutions and the collection distance on the surface morphology of fibers were discussed. The results indicated that n-HA mixing with solvent prior to other materimals for electrospingning could prepare the homogeneity of the spinning mixture. In all of the spinning conditions investigated,When using chloroform (CF) /N, N- dimethyl formamide (DMF) mixture as spinning solvent, PHB/PLLA/HA composite ultrafine fibers were not fabricated by electro-spinning, but chloroform can do. The average diameter of as-spun fibers increased with increasing concentration of PHB/PLLA/HA blends spinning solutions and collection distance. © (2013) Trans Tech Publications, Switzerland.

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