The new AUV driven by multi-vectored thrusters not only has unique kinematic characteristics during the actual cruise but also exists uncertain factors such as hydrodynamic coefficients perturbation and unknown interf...The new AUV driven by multi-vectored thrusters not only has unique kinematic characteristics during the actual cruise but also exists uncertain factors such as hydrodynamic coefficients perturbation and unknown interference of tail fluid, which bring difficult to the stability of the AUV＇s control system. In order to solve the nonlinear term and unmodeled dynamics existing in the new AUV＇s attitude control and the disturbances caused by the external marine environment, a second-order sliding mode controller with double-loop structure that considering the dynamic characteristics of the rudder actuators is designed, which improves the robustness of the system and avoids the control failure caused by the problem that the design theory of the sliding mode controller does not match with the actual application conditions. In order to avoid the loss of the sliding mode caused by the amplitude and rate constraints of the rudder actuator in the new AUV＇s attitude control, the dynamic boundary layer method is used to adjust the sliding boundary layer thickness so as to obtain the best anti-chattering effects. Then the impacts of system parameters, rudder actuator＇s constraints and boundary layer on the sliding mode controller are computed and analyzed to verify the effectiveness and robustness of the sliding mode controller based on dynamic boundary layer. The computational results show that the original divergent second-order sliding mode controller can still effectively implement the AUV＇s attitude control through dynamically adjusting the sliding boundary layer thickness. The dynamic boundary layer method ensures the stability of the system and does not exceed the amplitude constraint of the rudder actuator, which provides a theoretical guidance and technical support for the control system design of the new AUV in real complex sea conditions.展开更多
1 Introduction In the present paper,MgCl2·6H2O,FeCl3·6H2O,and CeCl3·6H2O were used as raw materials in the precipitationhydrothermal method to synthesize MgF eC e hydrotalcite.The effects of the Fe:Ce m...1 Introduction In the present paper,MgCl2·6H2O,FeCl3·6H2O,and CeCl3·6H2O were used as raw materials in the precipitationhydrothermal method to synthesize MgF eC e hydrotalcite.The effects of the Fe:Ce molar ratio on the composition,crystal structure,and thermal stability of hydrotalcite are examined.Energy-dispersive X-ray spectroscopy(EDS),X-展开更多
An ultrahigh vacuum chemical vapor deposition (UHV/CVD) system is developed and the details of its construction and operation are reported. Using high purity SiH4 and GeH4 reactant gases, the Si0.82Ge0.18 layer is dep...An ultrahigh vacuum chemical vapor deposition (UHV/CVD) system is developed and the details of its construction and operation are reported. Using high purity SiH4 and GeH4 reactant gases, the Si0.82Ge0.18 layer is deposited at 550℃. With the measurements by double crystal X-ray diffraction (DCXRD), transmission electron microscopy (TEM) and Rutherford backscattering spectroscppy (RBS) techniques, it is shown that the crystalline quality of the SiGe layer is good, and the underlying SiGe/Si heterointerface is sharply defined.展开更多
Double-layer organic electroluminescent devices have been constructed. A new fluorescent dye, 9,10-bis(phenylethynyl)anthracence, was chosen as the dopant which was molecularly dispersed in the polymer film, and green...Double-layer organic electroluminescent devices have been constructed. A new fluorescent dye, 9,10-bis(phenylethynyl)anthracence, was chosen as the dopant which was molecularly dispersed in the polymer film, and green light was observed from the device with luminance of 130cd/m(2) at 17V.展开更多
This paper takes the innovative enterprises with substantial financing in2014-2016 as the research sample,uses the foundation layer enterprises under the same conditions as the contrast,and uses the data envelopment a...This paper takes the innovative enterprises with substantial financing in2014-2016 as the research sample,uses the foundation layer enterprises under the same conditions as the contrast,and uses the data envelopment analysis to do empirical research. By comparing the comprehensive technical efficiency,pure technical efficiency and scale efficiency of the sample enterprises and the controlled enterprises,and through the analysis of slack variables of non DEA efficient enterprises,the reasons for the low efficiency and the improvement direction are pointed out. The results show that the financing efficiency of innovation layer enterprises is obviously higher than that of the underlying enterprises,and the financing efficiency has also improved in recent years,but there are still unstable factors,main problem of which is poor operating capacity of funds.展开更多
基金supported by National Hi-tech Research and Development Program of China (863 Program,Grant No.2006AA09Z235)Hunan Provincial Innovation Foundation for Postgraduate of China (Grant No. CX2009B003)
文摘The new AUV driven by multi-vectored thrusters not only has unique kinematic characteristics during the actual cruise but also exists uncertain factors such as hydrodynamic coefficients perturbation and unknown interference of tail fluid, which bring difficult to the stability of the AUV＇s control system. In order to solve the nonlinear term and unmodeled dynamics existing in the new AUV＇s attitude control and the disturbances caused by the external marine environment, a second-order sliding mode controller with double-loop structure that considering the dynamic characteristics of the rudder actuators is designed, which improves the robustness of the system and avoids the control failure caused by the problem that the design theory of the sliding mode controller does not match with the actual application conditions. In order to avoid the loss of the sliding mode caused by the amplitude and rate constraints of the rudder actuator in the new AUV＇s attitude control, the dynamic boundary layer method is used to adjust the sliding boundary layer thickness so as to obtain the best anti-chattering effects. Then the impacts of system parameters, rudder actuator＇s constraints and boundary layer on the sliding mode controller are computed and analyzed to verify the effectiveness and robustness of the sliding mode controller based on dynamic boundary layer. The computational results show that the original divergent second-order sliding mode controller can still effectively implement the AUV＇s attitude control through dynamically adjusting the sliding boundary layer thickness. The dynamic boundary layer method ensures the stability of the system and does not exceed the amplitude constraint of the rudder actuator, which provides a theoretical guidance and technical support for the control system design of the new AUV in real complex sea conditions.
基金supported by China Postdoctoral Science Foundation(No.118918)West Light Foundation of the Chinese Academy of Science
文摘1 Introduction In the present paper,MgCl2·6H2O,FeCl3·6H2O,and CeCl3·6H2O were used as raw materials in the precipitationhydrothermal method to synthesize MgF eC e hydrotalcite.The effects of the Fe:Ce molar ratio on the composition,crystal structure,and thermal stability of hydrotalcite are examined.Energy-dispersive X-ray spectroscopy(EDS),X-
文摘An ultrahigh vacuum chemical vapor deposition (UHV/CVD) system is developed and the details of its construction and operation are reported. Using high purity SiH4 and GeH4 reactant gases, the Si0.82Ge0.18 layer is deposited at 550℃. With the measurements by double crystal X-ray diffraction (DCXRD), transmission electron microscopy (TEM) and Rutherford backscattering spectroscppy (RBS) techniques, it is shown that the crystalline quality of the SiGe layer is good, and the underlying SiGe/Si heterointerface is sharply defined.
文摘Double-layer organic electroluminescent devices have been constructed. A new fluorescent dye, 9,10-bis(phenylethynyl)anthracence, was chosen as the dopant which was molecularly dispersed in the polymer film, and green light was observed from the device with luminance of 130cd/m(2) at 17V.
基金This thesis is the staged achievement of 2017YCJR001 Program of Yancheng Financial Research Institute and is funded by Key Constructive Disciplines of Jiangsu Province-Applied Econometrics
文摘This paper takes the innovative enterprises with substantial financing in2014-2016 as the research sample,uses the foundation layer enterprises under the same conditions as the contrast,and uses the data envelopment analysis to do empirical research. By comparing the comprehensive technical efficiency,pure technical efficiency and scale efficiency of the sample enterprises and the controlled enterprises,and through the analysis of slack variables of non DEA efficient enterprises,the reasons for the low efficiency and the improvement direction are pointed out. The results show that the financing efficiency of innovation layer enterprises is obviously higher than that of the underlying enterprises,and the financing efficiency has also improved in recent years,but there are still unstable factors,main problem of which is poor operating capacity of funds.
