The research on high-performance vector control of permanent magnet synchronous motor(PMSM)drive system plays an extremely important role in electrical drive system.To further improve the speed control performance of ...The research on high-performance vector control of permanent magnet synchronous motor(PMSM)drive system plays an extremely important role in electrical drive system.To further improve the speed control performance of the system,a fast non-singular end sliding mode(FNTSM)surface function based on traditional NTSM control is developed.The theoretical analysis proves that the FNTSM surface function has a faster dynamic response and more finite-time convergence.In addition,for the self-vibration problem caused by high sliding mode switching gain,an FNTSM control method with anti-disturbance capability was designed based on the linear disturbance observer(DO),i.e.the FNTSMDO method was employed to devise the PMSM speed regulator.The comparative simulation and experiment results with traditional PI control and NTSM control methods indicate that the FNTSMDO method could improve the dynamic performance and anti-interference of the system.展开更多
The effect of the distribution of organic cations CH3NH3^+(MA^+) on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuu...The effect of the distribution of organic cations CH3NH3^+(MA^+) on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuudopotentials. Generalized gradient approximation and local density approximation are used to optimize the geometries of six models, which are different in the orientation of organic cations. The results show that model C is more stable than others, and the main contribution to the top of valence band is from I 5p states. In the bottom of conduction bands, the main components are Pb 6s states with an overlapping of I 5p states. When the orientation of organic group is transforming, the Pb I6 octahedra will distort and the band structure will alter with it, which affect the generation and migration of photon-generated carriers and optical properties.展开更多
Dear Editor,This letter is concerned with quadratic L_(2) performance(quadratic stability and L_(2) gain)for switched uncertain linear systems(SULS)with norm-bounded uncertainties.Assuming that no single uncertain sub...Dear Editor,This letter is concerned with quadratic L_(2) performance(quadratic stability and L_(2) gain)for switched uncertain linear systems(SULS)with norm-bounded uncertainties.Assuming that no single uncertain subsystem achieves quadratic L_(2) performanceγbut a convex combination of the subsystems can make it,we propose a state-dependent switching law such that the SULS achieves the desired quadratic L_(2) performance.The discussion is extended to the SULS with state feedback control,and a sufficient condition is proposed to design the state feedback gains and the switching law simultaneously.展开更多
In high voltage input DC-DC converter, auxiliary winding of isolation transformer is usually used to supply power for control circuit. Due to the wide-range of input voltage, the variable output voltage of auxiliary w...In high voltage input DC-DC converter, auxiliary winding of isolation transformer is usually used to supply power for control circuit. Due to the wide-range of input voltage, the variable output voltage of auxiliary winding will cause a series of problems, such as variable drive pulse amplitude, increased driver switching devices loss and drive transformer core saturation. This paper analyzes the influence of variable output voltage of auxiliary winding in detail. A novel method is proposed to solve the problem of large variation range of auxiliary winding output voltage, which is adding a buck converter between the auxiliary winding and the control circuit. A dual switch forward convert has been designed with 300 V - 800 V input and 24 V/5 A output. The results show that this method is effective by comparing the different results of using buck converter or not.展开更多
Geometric and electronic structures of three polymorphs of BiPO4(m MBIP, n MBIP and HBIP) have been investigated by the first-principles calculations. The results show that PO4 tetrahedron in n MBIP is distorted mos...Geometric and electronic structures of three polymorphs of BiPO4(m MBIP, n MBIP and HBIP) have been investigated by the first-principles calculations. The results show that PO4 tetrahedron in n MBIP is distorted most, and m MBIP possesses minimum effective mass of carriers in three polymorphs of BiPO4. Further, the leading role of inductive effect of dipole moment or effective mass of carries in the separation of electron-hole pairs is analyzed. Based on the fact that n MBIP has higher photocatalytic activity than m MBIP, it can be inferred that the inductive effect of dipole moment deriving from distorted PO4 tetrahedron is the dominant factor affecting the separation efficiency of carries. The calculated results represent that n MBIP has more appropriate redox potential and narrower band gap than others. These findings may provide meaningful guidance for further understanding on the relationship between unique crystal structure and photocatalytic activity of BiPO4.展开更多
A strategy for the preparation nitrogen-doped carbon encapsulated Si nanocomposite with a void layer(Si@void@NC)is proposed,in which the nitrogen doping content in the carbon layer is tunable.Aniline and ortho-phenyle...A strategy for the preparation nitrogen-doped carbon encapsulated Si nanocomposite with a void layer(Si@void@NC)is proposed,in which the nitrogen doping content in the carbon layer is tunable.Aniline and ortho-phenylenediamine are both selected as the nitrogen,carbon sources and co-polymerized on Si@SiO_(2),in which SiO_(2)is functionalized as a void template.SEM and TEM observation show that Si nanoparticles are encapsulated in a hollow and interconnected carbon cages with a thickness of less than 10 nm,which is inclined to agglomerate together to form larger particles in micrometer scale.The variation of mole ratio of aniline and ortho-phenylenediamine will enable the change of nitrogen doping level in the carbon layer and ranges from 3.2%to 8.4%.The nitrogen is doped into the carbon framework in the form of pyridinic,pyrrolic and graphitic nitrogen.Electrochemical tests indicate that the nitrogen content influences the SEI formation and the lithiation of Si nanoparticles.The potential for the decomposition of electrolyte to form SEI film and the alloying of Si-Li negatively shift when the nitrogen doping content is increased.Furthermore,the cycling performance of Si@void@NC is improved when raising the nitrogen content in the carbon.And the optimal nitrogen content is 7.5%,which is corresponding to the mole ratio of aniline to ortho-phenylenediamine is 5:5.展开更多
The bionics-based swarm intelligence optimization algorithm is a typical natural heuristic algorithm whose goal is to find the global optimal solution of the optimization problem.It simulates the group behavior of var...The bionics-based swarm intelligence optimization algorithm is a typical natural heuristic algorithm whose goal is to find the global optimal solution of the optimization problem.It simulates the group behavior of various animals and uses the information exchange and cooperation between individuals to achieve optimal goals through simple and effective interaction with experienced and intelligent individuals.This paper first introduces the principles of various swarm intelligent optimization algorithms.Then,the typical application of these swarm intelligence optimization algorithms in various fields is listed.After that,the advantages and defects of all swarm intelligence optimization algorithms are summarized.Next,the improvement strategies of various swarm intelligence optimization algorithms are explained.Finally,the future development of various swarm intelligence optimization algorithms is prospected.展开更多
Differential absorption lidar(DIAL) is an excellent technology for atmospheric CO2 detection. However, the accuracy and stability of a transmitted on-line wavelength are strictly required in a DIAL system. The fluctua...Differential absorption lidar(DIAL) is an excellent technology for atmospheric CO2 detection. However, the accuracy and stability of a transmitted on-line wavelength are strictly required in a DIAL system. The fluctuation of a tunable pulsed laser system is relatively more serious than that of other laser sources, and this condition leads to a large measurement error for the lidar signal. These concerns pose a significant challenge in on-line wavelength calibration. This study proposes an alternative method based on wavelet modulus maxima for the accurate on-line wavelength calibration of a pulsed laser. Because of the different propagation characteristics of the wavelet transform modulus maxima between signal and noise, the singularities of a signal can be obtained by detection of the local modulus maxima in the wavelet transform maximum at fine scales. Simulated analysis shows that the method is more accurate than the general method such as quintic polynomial fitting and can steadily maintain high calibration precision at different signal-to-noise ratios(SNRs). Last, 16 groups of real experiments were conducted to verify the simulated analysis, which shows that the proposed method is an alternative for accurately calibrating an on-line wavelength. In addition, the proposed method is able to suppress noises in the process of wavelength calibration, which gives it an advantage in accurate on-line wavelength calibration with a low SNR.展开更多
The effect of relaxation on the energetics and electronic structure of clean Ag3PO4(111) surface has been studied, carried out using first-principles density functional theory(DFT) incorporating the GGACU formalis...The effect of relaxation on the energetics and electronic structure of clean Ag3PO4(111) surface has been studied, carried out using first-principles density functional theory(DFT) incorporating the GGACU formalism.After atomic relaxation of the Ag3PO4(111) surface, it is found that O atoms are exposed to the outermost surface,due to an inward displacement of more than 0.06 nm for the two threefold-coordinated Ag atoms and an outward displacement of about 0.004 nm for three O atoms in the sublayer. The atomic relaxations result in a large transfer of surface charges from the outermost layer to the inner layer, and the surface bonds have a rehybridization, which makes the covalence increase and thus causes the surface bonds to shorten. The calculated energy band structures and density of states of the Ag3PO4(111) surface present that the atomic relaxation narrows the valence band width0.15 e V and increases the band gap width 0.26 e V. Meantime, the two surface peaks for the unrelaxed structure disappear at the top of the valence band and the bottom of the conduction band after the relaxed structure, which induces the transformation from a metallic to a semi-conducting characteristic.展开更多
Prolonging the lifespan of oxygen catalysts in Zn-air batteries was urgently required for the potential commercialization.Herein,two interactional active species were integrated into porous N-doped carbon microspheres...Prolonging the lifespan of oxygen catalysts in Zn-air batteries was urgently required for the potential commercialization.Herein,two interactional active species were integrated into porous N-doped carbon microspheres(Co-Fe-Ru/PNCS)to act as bifunctional oxygen electrocatalysts.Due to the electron transfer from Ru to Co/Fe element,the high value state of Ru could promote OER performance and reduce the charge voltage of the battery.An extended cycle stability of 200 h was achieved in Co-Fe-Ru/PNCS-based battery.Moreover,the quasi in-situ potentiodynamic sweep of air-electrode in battery cell confirmed it was the incorporation of Ru that avoided the passivation of Co/Fe-based nanoparticles.Accordingly,this novel electrocatalyst may provide a new strategy of designing durable bifunctional oxygen electrocatalyst for Zn-air batteries.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 51507188Doctoral Research Startup Foundation of Hubei University of Technology under Grant XJ2021000302。
文摘The research on high-performance vector control of permanent magnet synchronous motor(PMSM)drive system plays an extremely important role in electrical drive system.To further improve the speed control performance of the system,a fast non-singular end sliding mode(FNTSM)surface function based on traditional NTSM control is developed.The theoretical analysis proves that the FNTSM surface function has a faster dynamic response and more finite-time convergence.In addition,for the self-vibration problem caused by high sliding mode switching gain,an FNTSM control method with anti-disturbance capability was designed based on the linear disturbance observer(DO),i.e.the FNTSMDO method was employed to devise the PMSM speed regulator.The comparative simulation and experiment results with traditional PI control and NTSM control methods indicate that the FNTSMDO method could improve the dynamic performance and anti-interference of the system.
基金Supported by the program for National Natural Science Foundation of China(51102150,51472081)Foundation of Hubei University of Technology for High-level Talents(GCRC13014)Development Founds of Hubei Collaborative Innovation Center(HBSKFZD2014003,HBSKFZD2014011,HBSKFZD2015004)
文摘The effect of the distribution of organic cations CH3NH3^+(MA^+) on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuudopotentials. Generalized gradient approximation and local density approximation are used to optimize the geometries of six models, which are different in the orientation of organic cations. The results show that model C is more stable than others, and the main contribution to the top of valence band is from I 5p states. In the bottom of conduction bands, the main components are Pb 6s states with an overlapping of I 5p states. When the orientation of organic group is transforming, the Pb I6 octahedra will distort and the band structure will alter with it, which affect the generation and migration of photon-generated carriers and optical properties.
基金the National Natural Science Foundation of China(61903129)。
文摘Dear Editor,This letter is concerned with quadratic L_(2) performance(quadratic stability and L_(2) gain)for switched uncertain linear systems(SULS)with norm-bounded uncertainties.Assuming that no single uncertain subsystem achieves quadratic L_(2) performanceγbut a convex combination of the subsystems can make it,we propose a state-dependent switching law such that the SULS achieves the desired quadratic L_(2) performance.The discussion is extended to the SULS with state feedback control,and a sufficient condition is proposed to design the state feedback gains and the switching law simultaneously.
文摘In high voltage input DC-DC converter, auxiliary winding of isolation transformer is usually used to supply power for control circuit. Due to the wide-range of input voltage, the variable output voltage of auxiliary winding will cause a series of problems, such as variable drive pulse amplitude, increased driver switching devices loss and drive transformer core saturation. This paper analyzes the influence of variable output voltage of auxiliary winding in detail. A novel method is proposed to solve the problem of large variation range of auxiliary winding output voltage, which is adding a buck converter between the auxiliary winding and the control circuit. A dual switch forward convert has been designed with 300 V - 800 V input and 24 V/5 A output. The results show that this method is effective by comparing the different results of using buck converter or not.
基金supported by the National Natural Science Foundation of China(51472081,51102150)the Development Funds of Hubei Collaborative Innovation Center(HBSKFMS2014003,HBSKFMS2014011)+1 种基金the Foundation for High-Level Talents(GCRC13014)the Students Research Fund of Hubei Collaborative Innovation Center(HBSDY201511)
文摘Geometric and electronic structures of three polymorphs of BiPO4(m MBIP, n MBIP and HBIP) have been investigated by the first-principles calculations. The results show that PO4 tetrahedron in n MBIP is distorted most, and m MBIP possesses minimum effective mass of carriers in three polymorphs of BiPO4. Further, the leading role of inductive effect of dipole moment or effective mass of carries in the separation of electron-hole pairs is analyzed. Based on the fact that n MBIP has higher photocatalytic activity than m MBIP, it can be inferred that the inductive effect of dipole moment deriving from distorted PO4 tetrahedron is the dominant factor affecting the separation efficiency of carries. The calculated results represent that n MBIP has more appropriate redox potential and narrower band gap than others. These findings may provide meaningful guidance for further understanding on the relationship between unique crystal structure and photocatalytic activity of BiPO4.
基金supported by grants Hubei Province Technology Innovation Project(2018AAA056)Open Fund of Hubei Collaborative Innovation Center for High Efficient Utilization of Solar Energy(HBSKFZD2017006)+1 种基金Innovative Research and Development Institute of Guangdong(No.2018B090902009)Innovation and entrepreneurship training program for College Students(No.201710500024).
文摘A strategy for the preparation nitrogen-doped carbon encapsulated Si nanocomposite with a void layer(Si@void@NC)is proposed,in which the nitrogen doping content in the carbon layer is tunable.Aniline and ortho-phenylenediamine are both selected as the nitrogen,carbon sources and co-polymerized on Si@SiO_(2),in which SiO_(2)is functionalized as a void template.SEM and TEM observation show that Si nanoparticles are encapsulated in a hollow and interconnected carbon cages with a thickness of less than 10 nm,which is inclined to agglomerate together to form larger particles in micrometer scale.The variation of mole ratio of aniline and ortho-phenylenediamine will enable the change of nitrogen doping level in the carbon layer and ranges from 3.2%to 8.4%.The nitrogen is doped into the carbon framework in the form of pyridinic,pyrrolic and graphitic nitrogen.Electrochemical tests indicate that the nitrogen content influences the SEI formation and the lithiation of Si nanoparticles.The potential for the decomposition of electrolyte to form SEI film and the alloying of Si-Li negatively shift when the nitrogen doping content is increased.Furthermore,the cycling performance of Si@void@NC is improved when raising the nitrogen content in the carbon.And the optimal nitrogen content is 7.5%,which is corresponding to the mole ratio of aniline to ortho-phenylenediamine is 5:5.
基金This work was supported by the National Natural Science Foundation of China(61601177)the Science and Technology Research Program of Hubei Provincial Department of Education(Q20171401)。
文摘The bionics-based swarm intelligence optimization algorithm is a typical natural heuristic algorithm whose goal is to find the global optimal solution of the optimization problem.It simulates the group behavior of various animals and uses the information exchange and cooperation between individuals to achieve optimal goals through simple and effective interaction with experienced and intelligent individuals.This paper first introduces the principles of various swarm intelligent optimization algorithms.Then,the typical application of these swarm intelligence optimization algorithms in various fields is listed.After that,the advantages and defects of all swarm intelligence optimization algorithms are summarized.Next,the improvement strategies of various swarm intelligence optimization algorithms are explained.Finally,the future development of various swarm intelligence optimization algorithms is prospected.
基金supported by the National Natural Science Foundation of China(41127901)the Program for Innovative Research Team in University of Ministry of Education of China(IRT1278)+2 种基金the National Science Foundation of Hubei province(2015CFA002)the China Postdoctoral Science Foundation(2015M570667)the Fundamental Research Funds for the Central Universities(2042015kf0015)
文摘Differential absorption lidar(DIAL) is an excellent technology for atmospheric CO2 detection. However, the accuracy and stability of a transmitted on-line wavelength are strictly required in a DIAL system. The fluctuation of a tunable pulsed laser system is relatively more serious than that of other laser sources, and this condition leads to a large measurement error for the lidar signal. These concerns pose a significant challenge in on-line wavelength calibration. This study proposes an alternative method based on wavelet modulus maxima for the accurate on-line wavelength calibration of a pulsed laser. Because of the different propagation characteristics of the wavelet transform modulus maxima between signal and noise, the singularities of a signal can be obtained by detection of the local modulus maxima in the wavelet transform maximum at fine scales. Simulated analysis shows that the method is more accurate than the general method such as quintic polynomial fitting and can steadily maintain high calibration precision at different signal-to-noise ratios(SNRs). Last, 16 groups of real experiments were conducted to verify the simulated analysis, which shows that the proposed method is an alternative for accurately calibrating an on-line wavelength. In addition, the proposed method is able to suppress noises in the process of wavelength calibration, which gives it an advantage in accurate on-line wavelength calibration with a low SNR.
基金Project supported by the National Natural Science Foundation of China(Nos.51472081,51102150,61106046)the Development Funds of Hubei Collaborative Innovation Center(Nos.HBSKFMS2014003,HBSKFMS2014011)the Foundation for High-Level Talents(No.GCRC13014)
文摘The effect of relaxation on the energetics and electronic structure of clean Ag3PO4(111) surface has been studied, carried out using first-principles density functional theory(DFT) incorporating the GGACU formalism.After atomic relaxation of the Ag3PO4(111) surface, it is found that O atoms are exposed to the outermost surface,due to an inward displacement of more than 0.06 nm for the two threefold-coordinated Ag atoms and an outward displacement of about 0.004 nm for three O atoms in the sublayer. The atomic relaxations result in a large transfer of surface charges from the outermost layer to the inner layer, and the surface bonds have a rehybridization, which makes the covalence increase and thus causes the surface bonds to shorten. The calculated energy band structures and density of states of the Ag3PO4(111) surface present that the atomic relaxation narrows the valence band width0.15 e V and increases the band gap width 0.26 e V. Meantime, the two surface peaks for the unrelaxed structure disappear at the top of the valence band and the bottom of the conduction band after the relaxed structure, which induces the transformation from a metallic to a semi-conducting characteristic.
基金support of the research start-up fund of Hubei University of Technology(No.XJ2021007701)Nature Science Foundation of Hubei Province(2021CFB291)。
文摘Prolonging the lifespan of oxygen catalysts in Zn-air batteries was urgently required for the potential commercialization.Herein,two interactional active species were integrated into porous N-doped carbon microspheres(Co-Fe-Ru/PNCS)to act as bifunctional oxygen electrocatalysts.Due to the electron transfer from Ru to Co/Fe element,the high value state of Ru could promote OER performance and reduce the charge voltage of the battery.An extended cycle stability of 200 h was achieved in Co-Fe-Ru/PNCS-based battery.Moreover,the quasi in-situ potentiodynamic sweep of air-electrode in battery cell confirmed it was the incorporation of Ru that avoided the passivation of Co/Fe-based nanoparticles.Accordingly,this novel electrocatalyst may provide a new strategy of designing durable bifunctional oxygen electrocatalyst for Zn-air batteries.