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Guo G.,Shaanxi University of Science and Technology | Li B.,Shaanxi Railway Institute | Lin X.,Shaanxi University of Science and Technology
Computers and Mathematics with Applications | Year: 2014

This paper is concerned with spatially homogeneous and inhomogeneous autocatalysis models with arbitrary order. For the spatially homogeneous model, the existence and stability of Hopf bifurcation surrounding the interior equilibrium are considered. For the model subject to zero-flux boundary conditions, Turing instability of the interior equilibrium is firstly discussed and Turing instability region regarding the diffusion coefficients is established. Then by the center manifold theory and normal form method, the existence of Hopf bifurcation and the stability of bifurcating periodic solutions are obtained, which is much more difficult and complicated than dealing with the spatially homogeneous case. Finally, to verify our analytical results, some examples of numerical simulations are also included. © 2013 Elsevier Ltd. All rights reserved. Source

Wang Z.,Northwestern Polytechnical University | Wang Z.,Changan University | Li K.,Northwestern Polytechnical University | Wang C.,Shaanxi Railway Institute | Xie J.,Northwestern Polytechnical University
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2011

A lab-scale reflectivity test system was used to investigate wave absorbing properties of cement-based composites with carbon fiber and carbonyl iron powder/carbon fiber in a frequency range of 2-18 GHz. The microstructures and compositions of the composites were analyzed by scanning electron microscopy and X-ray diffractometer. The results show that the reflectivity of the composites with carbon fibers increases with increasing carbon fiber content in the frequency range of 2-8 GHz. In the high frequency range of 8-18 GHz, the wave absorbing property oscillation was larger when carbon fiber contents increased. Compared to the reflectivity of the composites with fiber content of 0.6%, the wave absorbing properties could not improved in the frequency range of 2-4 GHz when carbon fiber and carbonyl iron powder both were added. In the frequency range of 4-12 GHz, the reflectivity was decreased. In the frequency range of 12-18 GHz, a minimum reflectivity of -11.9 dB with a wave absorbing frequency band width of 7.3 GHz appeared and the wave was totally absorbed. The wave absorbing frequency band width of the composites with carbonyl iron powder at high frequencies was widened, and the variation of wave absorbing properties became smaller when carbonyl iron powder content increased. Source

Ligong S.,Shaanxi Railway Institute
Applied Mechanics and Materials | Year: 2012

In recent years, pump concrete construction technology is widely put in use because the modern architecture trends to over- height, large- span, and over-load. In the basis of the railway engineering examples, the thesis elaborates the ratio design of high-strength pump concrete, construction technology and quality control with reference to projects of the same kind. © (2012) Trans Tech Publications, Switzerland. Source

Zhang T.,Shaanxi Railway Institute | Wang Y.,Urban Rail Transit Engineering Co. of China Railway First Group Co.
Modern Tunnelling Technology | Year: 2015

A risk assessment and corresponding treatment are carried out for the special working conditions regarding shield tunnelling under houses for the Wuxi Metro Line 1 (from the College town station to the Xuelang station). There are two problems that need to be solved; 1) the passage under the houses, for which the earth pressure intensity shall be calculated and backfilling shall be adopted for the deep well, which may breakdown under the grouting pressure; and 2) maintaining construction safety during tunnelling under the old houses, whose foundational structures, service conditions, safety performance and controllable settlement shall be investigated and evaluated. For these problems, such construction countermeasures as uniform and continual shield driving, less correction of alignment deviation and regular monitoring are presented. The results show that these countermeasures are feasible and appropriate for the requirements of construction safety, including calculation of earth pressure intensity, control of shield tunnelling parameters, shield attitude adjustment and monitoring and measurement; when the shield passed beneath the houses, no danger occurred and the maximum settlement was 8.2 mm. ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved. Source

Jia L.,Shaanxi Railway Institute
Shenzhen Daxue Xuebao (Ligong Ban)/Journal of Shenzhen University Science and Engineering | Year: 2016

Based on a double twisted hexagonal wire mesh reinforced earth retaining wall built along an Expressway, we investigate the soil pressure in a cross section by field test and numerical simulation by FLAC, focusing on the horizontal and vertical earth pressures during and after wall construction. Results show that the earth pressures on the wall toe in 3 directions including horizontal, vertical, and 45° increase with the height of filling soil and gradually come to stability after wall construction, and the vertical earth pressures increase and the distribution for earth pressure at the same height is not uniform. The horizontal earth pressure on the back of the wall face increases fast at first but then decreases a little, appearing as a single peaked shape. The numerical simulation result coincides with the field test result. © 2016, Science Press. All right reserved. Source

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