Owing to the variability of mine surfaces, it is difficult to obtain the deformation monitoring data of the observation stations by traditional leveling technique. GPS RTK （Real-Time Kinematic） technique was employe...Owing to the variability of mine surfaces, it is difficult to obtain the deformation monitoring data of the observation stations by traditional leveling technique. GPS RTK （Real-Time Kinematic） technique was employed to the subsidence observation in this paper, and its main sources of errors including rover pole deflection of the vertical, un-modeled systematic errors （gross error, multipath delay etc.） and the height transformation error, were analyzed systematically. Based on the fundamental theories of spherical fit- ting and Empirical Mode Decomposition （EMD）, the error reduction models were studied exhaustively. And two experiments were done in different environment to test the proposed models. The results show that the proposed methods can achieve a fourth-grade leveling accuracy, with （Root-Mean-Square） RMS in three orthogonal directions （N, E and H） of 4.1, 3.3 and 3.1 ram, respectively, by 3-5 rain continuous shaking of the observation GPS antenna, fully satisfying for mine surface subsidence deformation monitoring.展开更多
An empirical hybrid shock absorber model capable of capturing nonlinear and hysteresis characteristics of shock absorbers is built.The nonlinear characteristics are modeled by algebraic function and the hysteresis eff...An empirical hybrid shock absorber model capable of capturing nonlinear and hysteresis characteristics of shock absorbers is built.The nonlinear characteristics are modeled by algebraic function and the hysteresis effects between shock force and shock velocity are modeled by neural network.To develop the empirical hybrid shock absorber model,a Mazda CX-7 front shock absorber is tested by a displacement-controlled hydraulic shock absorber testing machine.The hybrid shock absorber model is built and validated using the experimental shock absorber data.The RMS value for the hybrid shock absorber model is 60.28N at the velocity range from-1.3m/s to 1.3m/s.展开更多
In this paper,a rotational supercavitating evaporator(RSCE)was at first modeled by means of theoretical analysis approach.The geometrical characteristics of supercavity in the modeled RSCE were then studied through nu...In this paper,a rotational supercavitating evaporator(RSCE)was at first modeled by means of theoretical analysis approach.The geometrical characteristics of supercavity in the modeled RSCE were then studied through numerical simulations.The current research objectives consist in determination of shape of the supercavitator(which in the plane of rotation generates supercavity occupying the most volume between blades),and location of the area suitable for steam extraction by revealing the inner structure of supercavity.Analytical analysis was performed by solving empirical equations for the shape of RSCE,through which an evaluation of two-dimensional relative position of supercavity trailing edge for different shapes of the supercavitator has been realized.Numerical simulation was then carried out,by numerically solving the unsteady Navier-Stokes equations in their conservation form coupled with the Rayleigh-Plesset cavitation and Shear-Stress Transport turbulence models,for verification of the results obtained from empirical equations.Despite unreliable assumption of applicability of empirical equations we have confirmed similarity of the supercavity shapes obtained by both methods for the same RSCE.Therefore,the shape of supercavitator calculated by using empirical equations is acceptable,which provides a simple but reliable approach for design of RSCE.The inner structure of supercavity obtained by numerical simulation has indicated position and parameters for steam extraction openings for further numerical and experimental studies on the performance of RSCE.Practical application of steam or gas extraction is suggested for solving of some problems associated with cavitating pumping of cryogenic liquid.展开更多
基金sponsored by the National Natural Science Foundation of China (Nos.41074010, 41104005 and 40904004)the Scientific Research Foundation of Key Laboratory for Land Environment and Disaster Monitoring of SBSM (Nos.LEDM2010B12 and LEDM2009A01) the Jiangsu Qinglan Project
文摘Owing to the variability of mine surfaces, it is difficult to obtain the deformation monitoring data of the observation stations by traditional leveling technique. GPS RTK （Real-Time Kinematic） technique was employed to the subsidence observation in this paper, and its main sources of errors including rover pole deflection of the vertical, un-modeled systematic errors （gross error, multipath delay etc.） and the height transformation error, were analyzed systematically. Based on the fundamental theories of spherical fit- ting and Empirical Mode Decomposition （EMD）, the error reduction models were studied exhaustively. And two experiments were done in different environment to test the proposed models. The results show that the proposed methods can achieve a fourth-grade leveling accuracy, with （Root-Mean-Square） RMS in three orthogonal directions （N, E and H） of 4.1, 3.3 and 3.1 ram, respectively, by 3-5 rain continuous shaking of the observation GPS antenna, fully satisfying for mine surface subsidence deformation monitoring.
基金Supported by the National High Technology Research and Development Programme of China(No.2008AA11A143)
文摘An empirical hybrid shock absorber model capable of capturing nonlinear and hysteresis characteristics of shock absorbers is built.The nonlinear characteristics are modeled by algebraic function and the hysteresis effects between shock force and shock velocity are modeled by neural network.To develop the empirical hybrid shock absorber model,a Mazda CX-7 front shock absorber is tested by a displacement-controlled hydraulic shock absorber testing machine.The hybrid shock absorber model is built and validated using the experimental shock absorber data.The RMS value for the hybrid shock absorber model is 60.28N at the velocity range from-1.3m/s to 1.3m/s.
文摘In this paper,a rotational supercavitating evaporator(RSCE)was at first modeled by means of theoretical analysis approach.The geometrical characteristics of supercavity in the modeled RSCE were then studied through numerical simulations.The current research objectives consist in determination of shape of the supercavitator(which in the plane of rotation generates supercavity occupying the most volume between blades),and location of the area suitable for steam extraction by revealing the inner structure of supercavity.Analytical analysis was performed by solving empirical equations for the shape of RSCE,through which an evaluation of two-dimensional relative position of supercavity trailing edge for different shapes of the supercavitator has been realized.Numerical simulation was then carried out,by numerically solving the unsteady Navier-Stokes equations in their conservation form coupled with the Rayleigh-Plesset cavitation and Shear-Stress Transport turbulence models,for verification of the results obtained from empirical equations.Despite unreliable assumption of applicability of empirical equations we have confirmed similarity of the supercavity shapes obtained by both methods for the same RSCE.Therefore,the shape of supercavitator calculated by using empirical equations is acceptable,which provides a simple but reliable approach for design of RSCE.The inner structure of supercavity obtained by numerical simulation has indicated position and parameters for steam extraction openings for further numerical and experimental studies on the performance of RSCE.Practical application of steam or gas extraction is suggested for solving of some problems associated with cavitating pumping of cryogenic liquid.
