Numerical analysis of the optimal supporting time and long-term stability index of the surrounding rocks in the underground plant of Xiangjiaba hydro-power station was carried out based on the rheological theory. Firs...Numerical analysis of the optimal supporting time and long-term stability index of the surrounding rocks in the underground plant of Xiangjiaba hydro-power station was carried out based on the rheological theory. Firstly,the mechanical parameters of each rock group were identified from the experimental data; secondly,the rheological calculation and analysis for the cavern in stepped excavation without supporting were made; finally,the optimal time for supporting at the characteristic point in a typical section was obtained while the creep rate and displacement after each excavation step has satisfied the criterion of the optimal supporting time. Excavation was repeated when the optimal time for supporting was identified,and the long-term stability creep time and the maximum creep deformation of the characteristic point were determined in accordance with the criterion of long-term stability index. It is shown that the optimal supporting time of the characteristic point in the underground plant of Xiangjiaba hydro-power station is 5-8 d,the long-term stability time of the typical section is 126 d,and the corresponding largest creep deformation is 24.30 mm. While the cavern is supported,the cavern deformation is significantly reduced and the stress states of the surrounding rock masses are remarkably improved.展开更多
This paper carries out an experiment study of decoupling performance for a novel lateral axis micromachined gyroscope with varying environmental parameters. The non-ideal mathematical model for the coupling mechanism ...This paper carries out an experiment study of decoupling performance for a novel lateral axis micromachined gyroscope with varying environmental parameters. The non-ideal mathematical model for the coupling mechanism of the gyroscope is estab-lished through the gyro dynamic response matrix. The coupling components varying with ambient pressure and temperature induced by stiffness coupling, damping coupling and electrostatic force coupling are semi-analytically discussed. The overall coupling ratio is evaluated via experiments in the custom-built installation. The testing results show that the decoupling per-formance of the gyroscope is sensitive to the environmental parameters and all the non-ideal errors are determined as a function of ambient pressure and temperature. The coupling error varies from 0.05% to 0.25% within the pressure range of 100 Pa-100 kPa. The characteristics of coupling with temperature are measured from 20℃ to 100℃ with a variation from 0.35% to 0.41%. The results also indicate that within the range of measured ambient pressure and temperature, the minimum coupling ratio occurs at 100 Pa and room temperature. The overall performance of the gyroscope is tested under the pressure of about 2000 Pa and room temperature to achieve a relatively low coupling ratio. The scale factor is measured to be 7.8 mV （°）-1 s-1 with nonlinearity about 0.45% in the full-scale range of 600 （°） s-1. The short-term bias stability is approximately 0.06 （°）s-1 （1σ） for 20 min with noise equivalent angular rate evaluated to be 0.077 （°） s-1 Hz-1/2.展开更多
The HIV infection model of CD4＋ T-cells corresponds to a class of nonlinear ordinary differential equation systems. In this study, we provide the approximate solution of this model by using orthonormal Bernstein poly...The HIV infection model of CD4＋ T-cells corresponds to a class of nonlinear ordinary differential equation systems. In this study, we provide the approximate solution of this model by using orthonormal Bernstein polynomials （OBPs）. By applying the proposed method, the nonlinear system of ordinary differential equations reduces to a nonlinear system of algebraic equations which can be solved by using a suitable numerical method such as Newton＇s method. We prove some useful theorems concerning the convergence and error estimate associated to the present method. Finally, we apply the proposed method to get the numerical solution of this model with the arbitrary initial conditions and values. Furthermore, the numerical results obtained by the suggested method are compared with the results achieved by other previous methods. These results indicate that this method agrees with other previous methods.展开更多
基金Projects(50911130366, 50979030) supported by the National Natural Science Foundation of ChinaProject(2008BAB29B01) supported by the National Key Technology R&D Program of China
文摘Numerical analysis of the optimal supporting time and long-term stability index of the surrounding rocks in the underground plant of Xiangjiaba hydro-power station was carried out based on the rheological theory. Firstly,the mechanical parameters of each rock group were identified from the experimental data; secondly,the rheological calculation and analysis for the cavern in stepped excavation without supporting were made; finally,the optimal time for supporting at the characteristic point in a typical section was obtained while the creep rate and displacement after each excavation step has satisfied the criterion of the optimal supporting time. Excavation was repeated when the optimal time for supporting was identified,and the long-term stability creep time and the maximum creep deformation of the characteristic point were determined in accordance with the criterion of long-term stability index. It is shown that the optimal supporting time of the characteristic point in the underground plant of Xiangjiaba hydro-power station is 5-8 d,the long-term stability time of the typical section is 126 d,and the corresponding largest creep deformation is 24.30 mm. While the cavern is supported,the cavern deformation is significantly reduced and the stress states of the surrounding rock masses are remarkably improved.
文摘This paper carries out an experiment study of decoupling performance for a novel lateral axis micromachined gyroscope with varying environmental parameters. The non-ideal mathematical model for the coupling mechanism of the gyroscope is estab-lished through the gyro dynamic response matrix. The coupling components varying with ambient pressure and temperature induced by stiffness coupling, damping coupling and electrostatic force coupling are semi-analytically discussed. The overall coupling ratio is evaluated via experiments in the custom-built installation. The testing results show that the decoupling per-formance of the gyroscope is sensitive to the environmental parameters and all the non-ideal errors are determined as a function of ambient pressure and temperature. The coupling error varies from 0.05% to 0.25% within the pressure range of 100 Pa-100 kPa. The characteristics of coupling with temperature are measured from 20℃ to 100℃ with a variation from 0.35% to 0.41%. The results also indicate that within the range of measured ambient pressure and temperature, the minimum coupling ratio occurs at 100 Pa and room temperature. The overall performance of the gyroscope is tested under the pressure of about 2000 Pa and room temperature to achieve a relatively low coupling ratio. The scale factor is measured to be 7.8 mV （°）-1 s-1 with nonlinearity about 0.45% in the full-scale range of 600 （°） s-1. The short-term bias stability is approximately 0.06 （°）s-1 （1σ） for 20 min with noise equivalent angular rate evaluated to be 0.077 （°） s-1 Hz-1/2.
文摘The HIV infection model of CD4＋ T-cells corresponds to a class of nonlinear ordinary differential equation systems. In this study, we provide the approximate solution of this model by using orthonormal Bernstein polynomials （OBPs）. By applying the proposed method, the nonlinear system of ordinary differential equations reduces to a nonlinear system of algebraic equations which can be solved by using a suitable numerical method such as Newton＇s method. We prove some useful theorems concerning the convergence and error estimate associated to the present method. Finally, we apply the proposed method to get the numerical solution of this model with the arbitrary initial conditions and values. Furthermore, the numerical results obtained by the suggested method are compared with the results achieved by other previous methods. These results indicate that this method agrees with other previous methods.
