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Ding S.-J.,Xidian University | Ding S.-J.,The Third Engineer Scientific Research Institute of the General Staff | Ge D.-B.,Xidian University | Shen N.,Post University
Wuli Xuebao/Acta Physica Sinica | Year: 2010

The numerical reconstruction scheme of equivalent electromagnetic parameters for composite material is proposed based on the finite difference time domain (FDTD) method. To study the relationship between equivalent electromagnetic parameters and the bulk density of mixed medium, the reflection coefficient and transmission coefficient were firstly calculated by the FDTD method, and then the equivalent electromagnetic parameters were reconstructed by genetic algorithm and propagation matrix method under different blending ratios. When the blending ratio of composite material is low or high, the equivalent electromagnetic parameters calculated by the equivalent constitutive parameter formulas and numerical reconstruction scheme agree well with each other. The results are somewhat different only for the middle blending ratio. The results show the feasibility of the proposed numerical scheme for the reconstruction of equivalent electromagnetic parameters of composite material. © 2010 Chin. Phys. Soc.


Wang W.,PLA University of Science and Technology | Wang W.,The Third Engineer Scientific Research Institute of the General Staff | Xu H.,PLA University of Science and Technology | Tong Q.,PLA University of Science and Technology
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Salt caverns are created by the method that circulating fresh water into the salt formation to dissolve the salt, so the cavern's ratio of radius to height is small and the cavern can be simplified into a hollow cylinder. The intermediate zone of the cavern was sectioned to take as research object. Considering the fact that the salt deposit in China is characterized by more interlayer, an equivalent calculation model was established to discuss the stress distribution function near the layer, based on the method of equivalent relative displacement on contact surface between rock salt and interlayer and actual state. Where assuming the contact surface is smooth, and thus the elasticity solutions of the thick-walled cylinder could be used to calculate stress distribution, then local internal pressure near the interlayer are increased and decreased to adjust the relative displacement until equivalent to actual state. The contrast between the numerical simulation and analytic solution shows that two results on stress distribution considering effect of interlayer is basically the same, in which maximum error of radial stress σ r and circumferential stress σ θ on cavity surface are less than 6.8% and 2.7% respectively. The analytic result meets require of storage cavern design analysis.


Li H.,The Third Engineer Scientific Research Institute of the General Staff | Zhang S.,The Third Engineer Scientific Research Institute of the General Staff | Ouyang K.,The Third Engineer Scientific Research Institute of the General Staff
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Cylindrical structure is commonly used in the field of the city subway tunnel structure and other underground engineering. Based on the characteristics of the underground cylindrical structures and surrounding rock, the dynamic generalized function of cylindrical structure system in rocks subjected to plane shock wave is established, the linear and nonlinear dynamic differential equations of the system are derived by using variation principle. Applying the method to cylindrical structures with soft backfill layer in rocks, the elasticplastic dynamic responses of the structure are calculated. The effect of underground cylindrical structure dynamic characteristics and dynamic response of backfill layer thickness on the structure system are also researched. Meanwhile, the clipping vibration optimum thickness of soft backfilled layer and the best acoustic impedance ratio of the rock to backfill materials are worked out. The results are applicable to antiknock structure selection and structure dynamics analysis in the underground engineering under plane stress wave or earthquake loadings.

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