In order to study the uplifting effect of compensation grouting on ground surface and the upper structures,the ground heave induced by stratum expansion was considered as a stochastic process and the stochastic medium...In order to study the uplifting effect of compensation grouting on ground surface and the upper structures,the ground heave induced by stratum expansion was considered as a stochastic process and the stochastic medium theory was applied to determine the heave and deformation of ground surface under uniform and non-uniform expansion models of spherical grout bulb.The corresponding calculating formulas and simplified methods were derived based on the hypotheses of radial expansion.Then,a numerical model,in which radial velocity was imposed on the outer nodes of grout bulb to simulate the expansion process reaching a required volume strain,was established simultaneously.This new method avoids repeated trial calculation needed in the traditional method which applies a "fictitious" expanding pressure in the grouting elements.The results show that the numerical solutions have good consistency with the theoretical ones.Meanwhile,though the heave resulting from non-uniform expansion is larger than that from uniform expansion for shallow grouting,both of them tend to be convergent with the increasing of grouting depth.展开更多
For low power dielectric barrier discharge （DBD） used in small-size material treatment or portable devices, high- step transformer parasitic capacitance greatly influences the performance of the resonant converter a...For low power dielectric barrier discharge （DBD） used in small-size material treatment or portable devices, high- step transformer parasitic capacitance greatly influences the performance of the resonant converter as it is of the same order of magnitude as the equivalent capacitance of DBD load. In this paper, steady-state analysis of the low power DBD is presented, considering the inevitable parasitic capacitance of the high-step transformer. The rectifier-compensated first harmonic approxi- mation （RCFHA） is applied to linearize the equivalent load circuit of DBD at low frequency and the derived expressions are accurate and convenient for the analysis and design of the power supply. Based on the proposed linear equivalent load circuit, the influence of transformer parasitic capacitance on the key parameters, including the frequency range and the applied electrode voltage, is discussed when the power is regulated with pulse frequency modulation （PFM）. Also, a design procedure is presented based on the derived expressions. A prototype is constructed according to the design results and the accuracy of the design is verified by experimental results.展开更多
基金Project(2007AA11Z134) supported by the National High Technology Research and Development Program of ChinaProject(10JJ4035) supported by the Natural Science Foundation of Hunan Province,China Project(2010ybfz046) supported by the Fund of Excellent Doctoral Dissertation of Central South University,China
文摘In order to study the uplifting effect of compensation grouting on ground surface and the upper structures,the ground heave induced by stratum expansion was considered as a stochastic process and the stochastic medium theory was applied to determine the heave and deformation of ground surface under uniform and non-uniform expansion models of spherical grout bulb.The corresponding calculating formulas and simplified methods were derived based on the hypotheses of radial expansion.Then,a numerical model,in which radial velocity was imposed on the outer nodes of grout bulb to simulate the expansion process reaching a required volume strain,was established simultaneously.This new method avoids repeated trial calculation needed in the traditional method which applies a "fictitious" expanding pressure in the grouting elements.The results show that the numerical solutions have good consistency with the theoretical ones.Meanwhile,though the heave resulting from non-uniform expansion is larger than that from uniform expansion for shallow grouting,both of them tend to be convergent with the increasing of grouting depth.
基金supported by the National Natural Science Foundation of China(No.51107115)the China Postdoctoral Science Foundation(No.20110491766)
文摘For low power dielectric barrier discharge （DBD） used in small-size material treatment or portable devices, high- step transformer parasitic capacitance greatly influences the performance of the resonant converter as it is of the same order of magnitude as the equivalent capacitance of DBD load. In this paper, steady-state analysis of the low power DBD is presented, considering the inevitable parasitic capacitance of the high-step transformer. The rectifier-compensated first harmonic approxi- mation （RCFHA） is applied to linearize the equivalent load circuit of DBD at low frequency and the derived expressions are accurate and convenient for the analysis and design of the power supply. Based on the proposed linear equivalent load circuit, the influence of transformer parasitic capacitance on the key parameters, including the frequency range and the applied electrode voltage, is discussed when the power is regulated with pulse frequency modulation （PFM）. Also, a design procedure is presented based on the derived expressions. A prototype is constructed according to the design results and the accuracy of the design is verified by experimental results.
