In order to solve the decoupling control problem of multivariable system with time delays,a new decoupling Smith control method for multivariable system with time delays was proposed. Firstly,the decoupler based on th...In order to solve the decoupling control problem of multivariable system with time delays,a new decoupling Smith control method for multivariable system with time delays was proposed. Firstly,the decoupler based on the adjoint matrix of the multivariable system model with time delays was introduced,and the decoupled models were reduced to first-order plus time delay models by analyzing the amplitude-frequency and phase-frequency characteristics. Secondly,according to the closed-loop characteristic equation of Smith predictor structure,proportion integration (PI) controllers were designed following the principle of pole assignment for Butterworth filter. Finally,using small-gain theorem and Nyquist stability criterion,sufficient and necessary conditions for robust stability were analyzed with multiplicative uncertainties,which could be encountered frequently in practice. The result shows that the method proposed has superiority for response speed and load disturbance rejection performance.展开更多
Aiming to resolve the technical problems of lower gas concentrations and a reduced effective drainage period caused by gas-drainage borehole fracture development, a flexible gel （FG） gas-drainage borehole sealing ma...Aiming to resolve the technical problems of lower gas concentrations and a reduced effective drainage period caused by gas-drainage borehole fracture development, a flexible gel （FG） gas-drainage borehole sealing material was developed that adapts to borehole deformation. In this study, based on orthogonal tests, the effect of the ratio of material to water, stirring time and stirring speed on the viscosity, filtration property, water retention and pumpability of the FG were studied. The results indicate that the stirring speed, ratio of material to water and stirring time in turn increased the viscosity and the ratio of material to water, stirring time and stirring speed enhanced the filtration property and water retention. The FG pumps smoothly and achieves the optimal state of high water retention, low fluid loss and low viscosity when the ratio of material to water is 1：10, the stirring speed is 800 r/min, and the stirring time is 12 min. The field test results indicate that, after using the FG, the average drainage gas concentration increases by 25.9% and 27.6g and the average negative pressure of extraction increases by 2.7 kPa and 3.5 kPa com- pared with expansive cement and polyurethane, respectively.展开更多
基金Projects(60634020, 61074117) supported by the National Natural Science Foundation of China
文摘In order to solve the decoupling control problem of multivariable system with time delays,a new decoupling Smith control method for multivariable system with time delays was proposed. Firstly,the decoupler based on the adjoint matrix of the multivariable system model with time delays was introduced,and the decoupled models were reduced to first-order plus time delay models by analyzing the amplitude-frequency and phase-frequency characteristics. Secondly,according to the closed-loop characteristic equation of Smith predictor structure,proportion integration (PI) controllers were designed following the principle of pole assignment for Butterworth filter. Finally,using small-gain theorem and Nyquist stability criterion,sufficient and necessary conditions for robust stability were analyzed with multiplicative uncertainties,which could be encountered frequently in practice. The result shows that the method proposed has superiority for response speed and load disturbance rejection performance.
基金supported by the Central Universities Special Funds for Fundamental Research Funds of the China University of Mining and Technology (No. 2013ZDP01)the National Natural Science Foundation of China (Nos. 51274195 and U1361106)+3 种基金the Natural Science Foundation of Jiangsu Province (No. BK2012571)the National Major Scientific Instrument and Equipment Development Project (No. 2013YQ17046309)the Program for New Century Excellent Talents in University (No. NCET-12-0959)the Qing Lan Project
文摘Aiming to resolve the technical problems of lower gas concentrations and a reduced effective drainage period caused by gas-drainage borehole fracture development, a flexible gel （FG） gas-drainage borehole sealing material was developed that adapts to borehole deformation. In this study, based on orthogonal tests, the effect of the ratio of material to water, stirring time and stirring speed on the viscosity, filtration property, water retention and pumpability of the FG were studied. The results indicate that the stirring speed, ratio of material to water and stirring time in turn increased the viscosity and the ratio of material to water, stirring time and stirring speed enhanced the filtration property and water retention. The FG pumps smoothly and achieves the optimal state of high water retention, low fluid loss and low viscosity when the ratio of material to water is 1：10, the stirring speed is 800 r/min, and the stirring time is 12 min. The field test results indicate that, after using the FG, the average drainage gas concentration increases by 25.9% and 27.6g and the average negative pressure of extraction increases by 2.7 kPa and 3.5 kPa com- pared with expansive cement and polyurethane, respectively.
