A new method based on cross-spectrum estimation for the verification and validation of computer simulation models is expounded in accordance with the characteristics of missile systems. The new method can expose the d...A new method based on cross-spectrum estimation for the verification and validation of computer simulation models is expounded in accordance with the characteristics of missile systems. The new method can expose the differences between two time processes in several aspects and can also give quantitative analysis results about the statistical consistence between them. An application to an actual anti-tank missile system simulation is presented and the calculated results confirm the effectiveness of the method. The approach can also be employed to verify the simulation models of other dynamic systems.展开更多
To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" s...To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" simulation platform was established to carry out fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve the desired position and speed with sufficient accuracy.展开更多
For the materials that simultaneously exhibit piezoelectric and semiconductor properties,such as wurtzite Zn O,Ga N and In N,as well as two-dimensional single Mo S2,piezoelectric charges induced by externally applied ...For the materials that simultaneously exhibit piezoelectric and semiconductor properties,such as wurtzite Zn O,Ga N and In N,as well as two-dimensional single Mo S2,piezoelectric charges induced by externally applied strain can tune/control carrier transport at a metal-semiconductor contact or semiconductor junction,which is named piezotronic effect.Metal-semiconductor-metal piezotronic transistors are key piezotronic nanodevices for electromechanical applications,and they are typical nonlinear elements.In this paper,a simplified current-voltage analysis solution of piezotronic transistors is developed,which can be used for circuit design and simulation.Furthermore,the typical nonlinear circuit:Chua's circuit based on piezotronic transistors is simulated.We find that the output signal of the piezotronic transistor circuit can be switched and changed asymmetrically by externally applied strain.This study provides insight into the nonlinear properties of the piezotronic transistor,as well as guidance for piezotronic transistor nonlinear circuit application.展开更多
文摘A new method based on cross-spectrum estimation for the verification and validation of computer simulation models is expounded in accordance with the characteristics of missile systems. The new method can expose the differences between two time processes in several aspects and can also give quantitative analysis results about the statistical consistence between them. An application to an actual anti-tank missile system simulation is presented and the calculated results confirm the effectiveness of the method. The approach can also be employed to verify the simulation models of other dynamic systems.
基金the National Science Foundation under Grant No.50879014,No.50909025
文摘To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" simulation platform was established to carry out fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve the desired position and speed with sufficient accuracy.
基金supported by the Natural Science Foundation of Gansu Province,China(Grant No.145RJZA226)Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2013-35)Beijing Municipal Commission of Science and Technology(Grant Nos.Z131100006013005 and Z131100006013004)
文摘For the materials that simultaneously exhibit piezoelectric and semiconductor properties,such as wurtzite Zn O,Ga N and In N,as well as two-dimensional single Mo S2,piezoelectric charges induced by externally applied strain can tune/control carrier transport at a metal-semiconductor contact or semiconductor junction,which is named piezotronic effect.Metal-semiconductor-metal piezotronic transistors are key piezotronic nanodevices for electromechanical applications,and they are typical nonlinear elements.In this paper,a simplified current-voltage analysis solution of piezotronic transistors is developed,which can be used for circuit design and simulation.Furthermore,the typical nonlinear circuit:Chua's circuit based on piezotronic transistors is simulated.We find that the output signal of the piezotronic transistor circuit can be switched and changed asymmetrically by externally applied strain.This study provides insight into the nonlinear properties of the piezotronic transistor,as well as guidance for piezotronic transistor nonlinear circuit application.
