High-performance dielectric tunable materials with both high dielectric tunability and low dielectric loss are urgently needed for new-generation electronic tunable devices.In the present study,a new system,(Ba_(0.675...High-performance dielectric tunable materials with both high dielectric tunability and low dielectric loss are urgently needed for new-generation electronic tunable devices.In the present study,a new system,(Ba_(0.675)Sr_(0.325))_(1−x)La_(x)Ti_(1−x)MnxO_(3)(x=0.25%,0.5%,0.75%,and 1.0%),was designed.The acceptor dopant Mn was added to lower dielectric loss,while the donor dopant La was introduced to enhance dielectric tunability.The samples were prepared using the conventional solid-state(CS)reaction method and the semi-solution(SS)method.The experimental results showed that the morphology of the ceramics was optimized by further improving the processing procedure.Dense microstructures,homogeneous grains,and uniform dopant distributions could be achieved successfully by the semi-solution method.Moreover,a significant enhancement in the tunable properties was realized owing to the improved microstructure mentioned above.The optimum tunable properties occurred in the samples prepared by the semi-solution method at x=0.75%,with a high dielectric tunability of 85.0%,a low dielectric loss of 0.0011,and an excellent figure of merit(FOM)of 773.The tunable properties of(Ba,Sr)TiO_(3)(BST)ceramics were even superior to those of lead-based materials,with an FOM of approximately 700.All the results suggested that the semi-solution method rendered BST ceramics more promising for applications in tunable devices.展开更多
The complex refractive index of small ash particles is determined from the transmittance spectrum of dilute particle suspensions obtained from experiment and by the application of the precise Mie scattering theory and...The complex refractive index of small ash particles is determined from the transmittance spectrum of dilute particle suspensions obtained from experiment and by the application of the precise Mie scattering theory and dielectric dispersion Kramers-Kroning relations. The numerical simulation results for the ash particles with data given in literature [1] show that with this method the accuracy is improved and the applicable range of the wavelength and the particle size is expanded.At last the transmittance spectrum of the ash particle cloud from Tic Fa Coal Mine was measured by an infrared spectrometer and its complex refractive index is determined.展开更多
Discrete-type continuation method for solving nonlinear system of equations and Tikhonov's regularization method for solving linear ill-posed problems are combined into a stable and widely convergent one for solvi...Discrete-type continuation method for solving nonlinear system of equations and Tikhonov's regularization method for solving linear ill-posed problems are combined into a stable and widely convergent one for solving nonlinear operator equations with difficultly computed and ill-conditioned derivatives. Some results about their convergence are given The application of this method to solve the inverse problem of one-dimensional diffusion equation is demonstrated.展开更多
The adapting Runge-Kutta methods with a new interpolation procedure to delay differential equations was introduced by K.J. in't Hout in 1992[1], he proved that the numerical process, satisfies an important asympto...The adapting Runge-Kutta methods with a new interpolation procedure to delay differential equations was introduced by K.J. in't Hout in 1992[1], he proved that the numerical process, satisfies an important asymptotic stability condition. In this paper the convergence of this method under the asymptotic stability and other conditions in theorem 3 is proved.展开更多
Three main problems in system development and the plight of the system development are analyzed and discussed. Finally a practical and formalized method-object-oriented method is proposed to extncate the system develo...Three main problems in system development and the plight of the system development are analyzed and discussed. Finally a practical and formalized method-object-oriented method is proposed to extncate the system development from the predicament.展开更多
Based on the embedding thought, a method of wide convergence region for solving the coefficient inverse problem of wave equations in the space-time variable domain is presented. The numerical simulation shows that the...Based on the embedding thought, a method of wide convergence region for solving the coefficient inverse problem of wave equations in the space-time variable domain is presented. The numerical simulation shows that the method is feasible and effective.展开更多
The characterization of friction in control systems and its restraint by localization method are analyzed. The minimum velocity and position precision of control systems with friction are obtained analytically. The co...The characterization of friction in control systems and its restraint by localization method are analyzed. The minimum velocity and position precision of control systems with friction are obtained analytically. The condition of global stability is given.展开更多
An efficient finite element model of involute helical gear is presented. A program based on compliance matrix method is developed for the calculation of instantaneous meshing stiffness, and the relationship between th...An efficient finite element model of involute helical gear is presented. A program based on compliance matrix method is developed for the calculation of instantaneous meshing stiffness, and the relationship between the rate of meshing stiffness and overlap ratio is given. On the basis of stiffness calculation, an optimization program for the optimal design of profile modification is developed according to the principle of internal point punishment function method.展开更多
This paper discusses the modeling method of time series with neural network. In order to improve the adaptability of direct multi-step prediction models, this paper proposes a method of combining the temporal differen...This paper discusses the modeling method of time series with neural network. In order to improve the adaptability of direct multi-step prediction models, this paper proposes a method of combining the temporal differences methods with back-propagation algorithm for updating the parameters continuously on the basis of recent data. This method can make the neural network model fit the recent characteristic of the time series as close as possible, therefore improves the prediction accuracy. We built models and made predictions for the sunspot series. The prediction results of adaptive modeling method are better than that of non-adaptive modeling methods.展开更多
Torque ripple is one of the most important specification indexes of brushless DC torque motors. This paper analyzes the torque ripple of a sinusoidal-driven three-phase permanent magnet(PM) brushless DC (BLDC) torque ...Torque ripple is one of the most important specification indexes of brushless DC torque motors. This paper analyzes the torque ripple of a sinusoidal-driven three-phase permanent magnet(PM) brushless DC (BLDC) torque motor and approaches the expression of torque ripple. An indirect method using armature currents to measure torque ripple and its implementation by hardware are presented. The torque ripple of the motor is measured by the indirect and the direct methods respecively. The validity of the indirect method is demonstrated by the comparative analysis of the experimental results.展开更多
A Large balancing weight may be obtained by calculation, when the ordinary influence coefficient method is used. In this paper, a new residual value balance method is recommended. The fundamental idea of the new metho...A Large balancing weight may be obtained by calculation, when the ordinary influence coefficient method is used. In this paper, a new residual value balance method is recommended. The fundamental idea of the new method is on the principle of getting the minimized weight on condition that the vibration values at various points are less than the admitted ones. Experimental results show that this method is effective for balancing the insensitive rotor and rotors with special dynamic characteristics.展开更多
A numerical method is suggested to generate the blends with one of the blended surfaces being analytical.The method is more accurate, less complicated,more efficient and more intuitive.The formulation of equation set ...A numerical method is suggested to generate the blends with one of the blended surfaces being analytical.The method is more accurate, less complicated,more efficient and more intuitive.The formulation of equation set is presented in detail and the NURBS representation of the blending surface discussed.The algorithm has been implemented on PC.The method was tested by a couple of samples and got satisfactory results.展开更多
基金supported by the National Natural Science Foundation of China(No.U1966602).
文摘High-performance dielectric tunable materials with both high dielectric tunability and low dielectric loss are urgently needed for new-generation electronic tunable devices.In the present study,a new system,(Ba_(0.675)Sr_(0.325))_(1−x)La_(x)Ti_(1−x)MnxO_(3)(x=0.25%,0.5%,0.75%,and 1.0%),was designed.The acceptor dopant Mn was added to lower dielectric loss,while the donor dopant La was introduced to enhance dielectric tunability.The samples were prepared using the conventional solid-state(CS)reaction method and the semi-solution(SS)method.The experimental results showed that the morphology of the ceramics was optimized by further improving the processing procedure.Dense microstructures,homogeneous grains,and uniform dopant distributions could be achieved successfully by the semi-solution method.Moreover,a significant enhancement in the tunable properties was realized owing to the improved microstructure mentioned above.The optimum tunable properties occurred in the samples prepared by the semi-solution method at x=0.75%,with a high dielectric tunability of 85.0%,a low dielectric loss of 0.0011,and an excellent figure of merit(FOM)of 773.The tunable properties of(Ba,Sr)TiO_(3)(BST)ceramics were even superior to those of lead-based materials,with an FOM of approximately 700.All the results suggested that the semi-solution method rendered BST ceramics more promising for applications in tunable devices.
文摘The complex refractive index of small ash particles is determined from the transmittance spectrum of dilute particle suspensions obtained from experiment and by the application of the precise Mie scattering theory and dielectric dispersion Kramers-Kroning relations. The numerical simulation results for the ash particles with data given in literature [1] show that with this method the accuracy is improved and the applicable range of the wavelength and the particle size is expanded.At last the transmittance spectrum of the ash particle cloud from Tic Fa Coal Mine was measured by an infrared spectrometer and its complex refractive index is determined.
文摘Discrete-type continuation method for solving nonlinear system of equations and Tikhonov's regularization method for solving linear ill-posed problems are combined into a stable and widely convergent one for solving nonlinear operator equations with difficultly computed and ill-conditioned derivatives. Some results about their convergence are given The application of this method to solve the inverse problem of one-dimensional diffusion equation is demonstrated.
文摘The adapting Runge-Kutta methods with a new interpolation procedure to delay differential equations was introduced by K.J. in't Hout in 1992[1], he proved that the numerical process, satisfies an important asymptotic stability condition. In this paper the convergence of this method under the asymptotic stability and other conditions in theorem 3 is proved.
文摘Three main problems in system development and the plight of the system development are analyzed and discussed. Finally a practical and formalized method-object-oriented method is proposed to extncate the system development from the predicament.
文摘Based on the embedding thought, a method of wide convergence region for solving the coefficient inverse problem of wave equations in the space-time variable domain is presented. The numerical simulation shows that the method is feasible and effective.
文摘The characterization of friction in control systems and its restraint by localization method are analyzed. The minimum velocity and position precision of control systems with friction are obtained analytically. The condition of global stability is given.
文摘An efficient finite element model of involute helical gear is presented. A program based on compliance matrix method is developed for the calculation of instantaneous meshing stiffness, and the relationship between the rate of meshing stiffness and overlap ratio is given. On the basis of stiffness calculation, an optimization program for the optimal design of profile modification is developed according to the principle of internal point punishment function method.
文摘This paper discusses the modeling method of time series with neural network. In order to improve the adaptability of direct multi-step prediction models, this paper proposes a method of combining the temporal differences methods with back-propagation algorithm for updating the parameters continuously on the basis of recent data. This method can make the neural network model fit the recent characteristic of the time series as close as possible, therefore improves the prediction accuracy. We built models and made predictions for the sunspot series. The prediction results of adaptive modeling method are better than that of non-adaptive modeling methods.
文摘Torque ripple is one of the most important specification indexes of brushless DC torque motors. This paper analyzes the torque ripple of a sinusoidal-driven three-phase permanent magnet(PM) brushless DC (BLDC) torque motor and approaches the expression of torque ripple. An indirect method using armature currents to measure torque ripple and its implementation by hardware are presented. The torque ripple of the motor is measured by the indirect and the direct methods respecively. The validity of the indirect method is demonstrated by the comparative analysis of the experimental results.
文摘A Large balancing weight may be obtained by calculation, when the ordinary influence coefficient method is used. In this paper, a new residual value balance method is recommended. The fundamental idea of the new method is on the principle of getting the minimized weight on condition that the vibration values at various points are less than the admitted ones. Experimental results show that this method is effective for balancing the insensitive rotor and rotors with special dynamic characteristics.
文摘A numerical method is suggested to generate the blends with one of the blended surfaces being analytical.The method is more accurate, less complicated,more efficient and more intuitive.The formulation of equation set is presented in detail and the NURBS representation of the blending surface discussed.The algorithm has been implemented on PC.The method was tested by a couple of samples and got satisfactory results.
