A periodic one-dimensional four-state hopping model is proposed. In the model, the substeps between arbitrary adjacent states are unequal, and an explicit solution of the master equation is first obtained for the pro...A periodic one-dimensional four-state hopping model is proposed. In the model, the substeps between arbitrary adjacent states are unequal, and an explicit solution of the master equation is first obtained for the probability distribution as a function of the time and position for any initial distribution with all the transients included. Next, the transient behaviors in the initial period of time and the characteristic time to reach the steady state for the molecular motor are discussed. Finally, we compare the steady state results to experiments and illustrate qualitatively the kinetic behaviors of a molecular motor under external load F.展开更多
A novel active backstepping control method is presented for synchronizing two identical Roessler hyperchaotic systems with each other, and extended to achieve the generalized synchronization of the Chua chaotic system...A novel active backstepping control method is presented for synchronizing two identical Roessler hyperchaotic systems with each other, and extended to achieve the generalized synchronization of the Chua chaotic system with the Roessler hyperchaotic system. It is a systematic design approach and consists of a recursive procedure interlacing the choice of a Lyapunov function with the design of active control. In particular, this technique gives flexibility in constructing a control law. Numerical experiments verify the feasibility and effectiveness of the proposed control technique.展开更多
The structure, magnetization, and magnetocrystalline anisotropy were investigated using X-ray diffraction, vi-brating sample magnetometer, and AC susceptibility-meter. It is found that the microstructure of (Sm0.5Nd0....The structure, magnetization, and magnetocrystalline anisotropy were investigated using X-ray diffraction, vi-brating sample magnetometer, and AC susceptibility-meter. It is found that the microstructure of (Sm0.5Nd0.5)2(Fe1-xCox)17alloys is an (Sm,Nd)2(Fe,Co)17 phase with the rhombohedral Th2Zn17-type structure. The Curie temperature Tc increaseswith the Co concentration increasing, and the magnetization first increases as the Co content increases in(Smo.5Ndo.5)2(Fe1-xCox)17 alloys and then decreases slowly. The easy magnetization direction (EMD) of(Sm0.5Nd0.5)2(Fe0.25Co0.75)17 is along the c-axis and a strong enhancement of the crystalline anisotropy energy constant K isproduced by the addition of some Co atoms. The anisotropy energy constant reaches the maximum when x = 0.75 and thendecreases slowly with the Co content further increasing. The (Sm0.5Nd0.5)2(Fe0.25Co0.75)17 compound is an optical candidatefor the new permanent magnet, which possesses a high magnetization, a high Curie temperature, and a large anisotropy.展开更多
A Monte Carlo approach to simulate the transport and energy deposition of low energy electrons (E0≤10keV) in liquid water is presented. The elastic scattering of electrons is described by Mott cross section, which is...A Monte Carlo approach to simulate the transport and energy deposition of low energy electrons (E0≤10keV) in liquid water is presented. The elastic scattering of electrons is described by Mott cross section, which is derived from the relativistic wave equation of Dirac. The inelastic scattering model of electrons is based on the dielectric response theory with exchange effect included. A new method of sampling various inelastic scattering events is proposed in the simulation. Using the approach stated, the spatial distribution of inelastic scattering events and energy deposition of electrons in liquid water are computed and the results are compared with other theoretical studies.展开更多
Magnetic sensor arrays are proposed to measure electric current in a non-contac tway. In order to achieve higher accuracy, signal processing techniques for magnetic sensor arrays are utilized. Simulation techniques ar...Magnetic sensor arrays are proposed to measure electric current in a non-contac tway. In order to achieve higher accuracy, signal processing techniques for magnetic sensor arrays are utilized. Simulation techniques are necessary to study the factors influencing the accuracy of current measurement. This paper presents a simulation method to estimate the impact of sensing area and position of sensors on the accuracy of current measurement. Several error models are built up to support computer-aided design of magnetic sensor arrays.展开更多
In this review article, the motivation of studying inelastic energy loss for energetic electrons penetrating through matter and the corresponding technological importance have been outlined. The theoretical developmen...In this review article, the motivation of studying inelastic energy loss for energetic electrons penetrating through matter and the corresponding technological importance have been outlined. The theoretical development and method for the calculation of stopping powers are described. The stopping power data tables for a group of polymers and bioorganic compounds are presented, and the application aspects of the stopping power data are briefly discussed.展开更多
This paper deals with the experimental study on the correlation between insulation resistance ( R ) and direct current (DC) component ( i dc ) and corresponding aging degree of insulation in the course of the aging wi...This paper deals with the experimental study on the correlation between insulation resistance ( R ) and direct current (DC) component ( i dc ) and corresponding aging degree of insulation in the course of the aging within cross linked polyethylene (XLPE) insulation. The aging tests were performed on a section of 10 kV transmission XLPE cable by means of water needle method, and R was measured by DC voltage superimposed method. R and i dc were found to be significantly dependent on the corresponding aging degree of insulation in the course of aging of XLPE, and different kind of aging stage has different characteristics. Beside, there are generally similar regularity but different amplitude in the course of aging of XLPE insulation in different electrolyte, and the various electrochemical tree were found on the surface of aging XLPE cable immersed in CuSO 4 solution. Therefore, according to the changing regularity of the DC characteristic parameters i.e. R and i dc within XLPE insulation judging the aging degree of XLPE insulation will be an effective method.展开更多
We study force generation and motion of molecular motors using a simple two-state model in the paper.Asymmetric and periodic potential is adopted to describe the interaction between motor proteins and filaments that a...We study force generation and motion of molecular motors using a simple two-state model in the paper.Asymmetric and periodic potential is adopted to describe the interaction between motor proteins and filaments that are periodic and polar. The current and the slope of the effective potential as functions of the temperature and transition rates are calculated in the two-state model. The ratio of the slope of the effective potential to the current is also calculated. It is shown that the directed motion of motor proteins is relevant to the effective potential. The slope of the effective potential corresponds to an average force. The non-vanishing force therefore implies that detailed balance is broken in the process of transition between different states.展开更多
We study the collisions of energetic methane molecules with single-walled carbon nanotubes in the incident energyrange from 5 to 100 eV using classical molecular dynamics simulations combined with ab initio calculatio...We study the collisions of energetic methane molecules with single-walled carbon nanotubes in the incident energyrange from 5 to 100 eV using classical molecular dynamics simulations combined with ab initio calculations. Themethane molecules can be decomposed into different hydrocarbon radicals, e.g. CHn (n = 1-3), in the collisionsdepending on the incident energy. Chemical functionalization of the single-walled carbon nanotubes resulting fromthe chemical adsorption of these hydrocarbon radicals on the outside wall of single-walled carbon nanotubes canbe achieved simultaneously. Some stable adsorption configurations of hydrocarbon-functionalized single-walledcarbon nanotubes are also presented based on ab initio calculations.展开更多
A theoretical model is proposed in order to study the configuration resonance in s-SNOM. The electromagnetic coupling between the sample and the probe tip is described with the quasi-electrostatic field theory. This m...A theoretical model is proposed in order to study the configuration resonance in s-SNOM. The electromagnetic coupling between the sample and the probe tip is described with the quasi-electrostatic field theory. This method permits us to analyze the configurational resonance evoked by the interaction between the probe tip and the sample in s-SNOM intuitively. The resonant conditions for a certain system are presented in an explicit form. On the condition of considering the actual size of the sample dipoles and the probe dipole, we discuss the possibility of realizing the configurational resonance for various material samples. The numerical results indicate that the polarizability of the dielectric probe tip is too small to arouse this resonance, whereas, with the surface plasmon resonance emerging on the metallic nanoparticles, the enhanced polarizability of the metallic probe tip ensures the requirements of fulfilling the resonance.展开更多
The motion and equilibrium distribution of water molecules adsorbed inside neutral and negatively charged singlewalled carbon nanotubes (SWNTs) have been studied using molecular dynamics simulations (MDSs) at room tem...The motion and equilibrium distribution of water molecules adsorbed inside neutral and negatively charged singlewalled carbon nanotubes (SWNTs) have been studied using molecular dynamics simulations (MDSs) at room temperature based on CHARMM (Chemistry at HARvard Molecular Mechanics) potential parameters. We find that water molecules have a conspicuous electropism phenomenon and regular tubule patterns inside and outside the charged tube wall. The analyses of the motion behaviour of water molecules in the radial and axial directions show that by charging the SWNT, the adsorption efficiency is greatly enhanced, and the electric field produced by the charged SWNTs prevents water molecules from flowing out of the nanotube. However, water molecules can travel through the neutral SWNT in a fluctuating manner. This indicates that by electrically charging and uncharging the SWNTs, one can control the adsorption and transport behaviour of polar molecules in SWNTs for using as a stable storage medium or long transport channels. The transport velocity can be tailored by changing the charge on the SWNTs, which may have a further application as modulatable transport channels.展开更多
A high power continuous wave (CW) laser diode (LD) pumped acousto-optic Q-switched Nd:YVO4 laser is presented. A short pulse at the 1064 nm is obtained. With a repetition rate of 50 kHz,the maximum average output powe...A high power continuous wave (CW) laser diode (LD) pumped acousto-optic Q-switched Nd:YVO4 laser is presented. A short pulse at the 1064 nm is obtained. With a repetition rate of 50 kHz,the maximum average output power of 5.72 W is achieved. The optical conversion efficiency and the slope efficiency are up to 28% and 32.4% respectively. At the repetition rate of 10 kHz and the pulse width of 16.3ns, the maximum single pulse energy of 286 μJ and the peak power of 13kW are acquired. The laser can be used as a signal source in the free-space optical communication. The output signal agrees with the modulate signal well.展开更多
Based on the differential operator technique, a transverse Ising model (TIM) in the effective-field theory is developed to study the physical properties of a ferroelectric superlattice A3/B3 system. The effects of an ...Based on the differential operator technique, a transverse Ising model (TIM) in the effective-field theory is developed to study the physical properties of a ferroelectric superlattice A3/B3 system. The effects of an external electric field on the polarization, susceptibility and pyroelectric coefficient of the ferroelectric superlattice A3/B3 system are discussed in detail. The susceptibility of the ferroelectric superlattice A3/B3 system decreases with the increase of the electric field, implying that the polarization is weak.展开更多
The electric field in a surface discharge type ac-PDP cell with He or He/Xe(0.1%) mixture has been measured over a wide range of pressure (5-50 kPa) using laser induced fluorescence detection. The wall voltage was est...The electric field in a surface discharge type ac-PDP cell with He or He/Xe(0.1%) mixture has been measured over a wide range of pressure (5-50 kPa) using laser induced fluorescence detection. The wall voltage was estimated from the measured electric field, The Stark manifolds of triplet atomic helium Rydberg state (2s3S) with principal quantum numbers (n=8 and 9) have been used to measure the electric field, as the lifetime of 2s^3S is longer than the single atomic helium Rydberg state (2siS) in high pressure discharge. Comparison of the Stark manifolds between the n=9 and n=8 shows that the measurement accuracy of electric field can be increased by 10%, The maximum electric field strength during discharge and the wall voltage at the end of pulse decreases with the increase of pressure, The comparison of He and He/Xe(0.1%) discharge at 13 kPa showed that He/Xe gas mixture discharge can accumulate more wall charge on MgO surface and the electric field was somewhat higher than those of pure helium discharge during pulse off period under the same discharge conditions.展开更多
Electricity price is of the first consideration for all the participants in electric power market and its characteristics are related to both market mechanism and variation in the behaviors of market participants. It ...Electricity price is of the first consideration for all the participants in electric power market and its characteristics are related to both market mechanism and variation in the behaviors of market participants. It is necessary to build a real-time price forecasting model with adaptive capability; and because there are outliers in the price data, they should be detected and filtrated in training the forecasting model by regression method. In view of these points, this paper presents an electricity price forecasting method based on accurate on-line support vector regression (AOSVR) and outlier detection. Numerical testing results show that the method is effective in forecasting the electricity prices in electric power market.展开更多
An electromagnet design system is developed using Visual C++ language and OpenGL technology to visualize parametric 3D model. The system consists of primary design,optimization design, dynamic and static characteristi...An electromagnet design system is developed using Visual C++ language and OpenGL technology to visualize parametric 3D model. The system consists of primary design,optimization design, dynamic and static characteristics, and visual simulation. All empirical parameters and curves used in design process are stored in database. Through human-computer interactions, an electromagnetic system can be designed conveniently with the results and characteristics curves displayed in graphic model. Using this system can greatly shorten the process of product design, and the results satisfy technical requirements.展开更多
文摘A periodic one-dimensional four-state hopping model is proposed. In the model, the substeps between arbitrary adjacent states are unequal, and an explicit solution of the master equation is first obtained for the probability distribution as a function of the time and position for any initial distribution with all the transients included. Next, the transient behaviors in the initial period of time and the characteristic time to reach the steady state for the molecular motor are discussed. Finally, we compare the steady state results to experiments and illustrate qualitatively the kinetic behaviors of a molecular motor under external load F.
文摘A novel active backstepping control method is presented for synchronizing two identical Roessler hyperchaotic systems with each other, and extended to achieve the generalized synchronization of the Chua chaotic system with the Roessler hyperchaotic system. It is a systematic design approach and consists of a recursive procedure interlacing the choice of a Lyapunov function with the design of active control. In particular, this technique gives flexibility in constructing a control law. Numerical experiments verify the feasibility and effectiveness of the proposed control technique.
文摘The structure, magnetization, and magnetocrystalline anisotropy were investigated using X-ray diffraction, vi-brating sample magnetometer, and AC susceptibility-meter. It is found that the microstructure of (Sm0.5Nd0.5)2(Fe1-xCox)17alloys is an (Sm,Nd)2(Fe,Co)17 phase with the rhombohedral Th2Zn17-type structure. The Curie temperature Tc increaseswith the Co concentration increasing, and the magnetization first increases as the Co content increases in(Smo.5Ndo.5)2(Fe1-xCox)17 alloys and then decreases slowly. The easy magnetization direction (EMD) of(Sm0.5Nd0.5)2(Fe0.25Co0.75)17 is along the c-axis and a strong enhancement of the crystalline anisotropy energy constant K isproduced by the addition of some Co atoms. The anisotropy energy constant reaches the maximum when x = 0.75 and thendecreases slowly with the Co content further increasing. The (Sm0.5Nd0.5)2(Fe0.25Co0.75)17 compound is an optical candidatefor the new permanent magnet, which possesses a high magnetization, a high Curie temperature, and a large anisotropy.
文摘A Monte Carlo approach to simulate the transport and energy deposition of low energy electrons (E0≤10keV) in liquid water is presented. The elastic scattering of electrons is described by Mott cross section, which is derived from the relativistic wave equation of Dirac. The inelastic scattering model of electrons is based on the dielectric response theory with exchange effect included. A new method of sampling various inelastic scattering events is proposed in the simulation. Using the approach stated, the spatial distribution of inelastic scattering events and energy deposition of electrons in liquid water are computed and the results are compared with other theoretical studies.
基金Supported by National High-Tech Industry Development Project (1883)
文摘Magnetic sensor arrays are proposed to measure electric current in a non-contac tway. In order to achieve higher accuracy, signal processing techniques for magnetic sensor arrays are utilized. Simulation techniques are necessary to study the factors influencing the accuracy of current measurement. This paper presents a simulation method to estimate the impact of sensing area and position of sensors on the accuracy of current measurement. Several error models are built up to support computer-aided design of magnetic sensor arrays.
文摘In this review article, the motivation of studying inelastic energy loss for energetic electrons penetrating through matter and the corresponding technological importance have been outlined. The theoretical development and method for the calculation of stopping powers are described. The stopping power data tables for a group of polymers and bioorganic compounds are presented, and the application aspects of the stopping power data are briefly discussed.
基金Supported by the National Natural Science Foundation of China (59677018)
文摘This paper deals with the experimental study on the correlation between insulation resistance ( R ) and direct current (DC) component ( i dc ) and corresponding aging degree of insulation in the course of the aging within cross linked polyethylene (XLPE) insulation. The aging tests were performed on a section of 10 kV transmission XLPE cable by means of water needle method, and R was measured by DC voltage superimposed method. R and i dc were found to be significantly dependent on the corresponding aging degree of insulation in the course of aging of XLPE, and different kind of aging stage has different characteristics. Beside, there are generally similar regularity but different amplitude in the course of aging of XLPE insulation in different electrolyte, and the various electrochemical tree were found on the surface of aging XLPE cable immersed in CuSO 4 solution. Therefore, according to the changing regularity of the DC characteristic parameters i.e. R and i dc within XLPE insulation judging the aging degree of XLPE insulation will be an effective method.
文摘We study force generation and motion of molecular motors using a simple two-state model in the paper.Asymmetric and periodic potential is adopted to describe the interaction between motor proteins and filaments that are periodic and polar. The current and the slope of the effective potential as functions of the temperature and transition rates are calculated in the two-state model. The ratio of the slope of the effective potential to the current is also calculated. It is shown that the directed motion of motor proteins is relevant to the effective potential. The slope of the effective potential corresponds to an average force. The non-vanishing force therefore implies that detailed balance is broken in the process of transition between different states.
文摘We study the collisions of energetic methane molecules with single-walled carbon nanotubes in the incident energyrange from 5 to 100 eV using classical molecular dynamics simulations combined with ab initio calculations. Themethane molecules can be decomposed into different hydrocarbon radicals, e.g. CHn (n = 1-3), in the collisionsdepending on the incident energy. Chemical functionalization of the single-walled carbon nanotubes resulting fromthe chemical adsorption of these hydrocarbon radicals on the outside wall of single-walled carbon nanotubes canbe achieved simultaneously. Some stable adsorption configurations of hydrocarbon-functionalized single-walledcarbon nanotubes are also presented based on ab initio calculations.
基金This work was supported by the National Natural Science Founda-tion of China under grants No. 30170276.
文摘A theoretical model is proposed in order to study the configuration resonance in s-SNOM. The electromagnetic coupling between the sample and the probe tip is described with the quasi-electrostatic field theory. This method permits us to analyze the configurational resonance evoked by the interaction between the probe tip and the sample in s-SNOM intuitively. The resonant conditions for a certain system are presented in an explicit form. On the condition of considering the actual size of the sample dipoles and the probe dipole, we discuss the possibility of realizing the configurational resonance for various material samples. The numerical results indicate that the polarizability of the dielectric probe tip is too small to arouse this resonance, whereas, with the surface plasmon resonance emerging on the metallic nanoparticles, the enhanced polarizability of the metallic probe tip ensures the requirements of fulfilling the resonance.
文摘The motion and equilibrium distribution of water molecules adsorbed inside neutral and negatively charged singlewalled carbon nanotubes (SWNTs) have been studied using molecular dynamics simulations (MDSs) at room temperature based on CHARMM (Chemistry at HARvard Molecular Mechanics) potential parameters. We find that water molecules have a conspicuous electropism phenomenon and regular tubule patterns inside and outside the charged tube wall. The analyses of the motion behaviour of water molecules in the radial and axial directions show that by charging the SWNT, the adsorption efficiency is greatly enhanced, and the electric field produced by the charged SWNTs prevents water molecules from flowing out of the nanotube. However, water molecules can travel through the neutral SWNT in a fluctuating manner. This indicates that by electrically charging and uncharging the SWNTs, one can control the adsorption and transport behaviour of polar molecules in SWNTs for using as a stable storage medium or long transport channels. The transport velocity can be tailored by changing the charge on the SWNTs, which may have a further application as modulatable transport channels.
文摘A high power continuous wave (CW) laser diode (LD) pumped acousto-optic Q-switched Nd:YVO4 laser is presented. A short pulse at the 1064 nm is obtained. With a repetition rate of 50 kHz,the maximum average output power of 5.72 W is achieved. The optical conversion efficiency and the slope efficiency are up to 28% and 32.4% respectively. At the repetition rate of 10 kHz and the pulse width of 16.3ns, the maximum single pulse energy of 286 μJ and the peak power of 13kW are acquired. The laser can be used as a signal source in the free-space optical communication. The output signal agrees with the modulate signal well.
文摘Based on the differential operator technique, a transverse Ising model (TIM) in the effective-field theory is developed to study the physical properties of a ferroelectric superlattice A3/B3 system. The effects of an external electric field on the polarization, susceptibility and pyroelectric coefficient of the ferroelectric superlattice A3/B3 system are discussed in detail. The susceptibility of the ferroelectric superlattice A3/B3 system decreases with the increase of the electric field, implying that the polarization is weak.
文摘The electric field in a surface discharge type ac-PDP cell with He or He/Xe(0.1%) mixture has been measured over a wide range of pressure (5-50 kPa) using laser induced fluorescence detection. The wall voltage was estimated from the measured electric field, The Stark manifolds of triplet atomic helium Rydberg state (2s3S) with principal quantum numbers (n=8 and 9) have been used to measure the electric field, as the lifetime of 2s^3S is longer than the single atomic helium Rydberg state (2siS) in high pressure discharge. Comparison of the Stark manifolds between the n=9 and n=8 shows that the measurement accuracy of electric field can be increased by 10%, The maximum electric field strength during discharge and the wall voltage at the end of pulse decreases with the increase of pressure, The comparison of He and He/Xe(0.1%) discharge at 13 kPa showed that He/Xe gas mixture discharge can accumulate more wall charge on MgO surface and the electric field was somewhat higher than those of pure helium discharge during pulse off period under the same discharge conditions.
基金This paper is about a project financed by the National Outstanding Young Investigator Grant (6970025)863 High Tech Development Plan of China (2001AA413910) the Project of National Natural Science Foundation (60274054) the Key Project of National Natural Science Foundation (59937150)it is also supported by its cooperating project financed by 863 High Tech Development Plan of China (2004AA412050).
文摘Electricity price is of the first consideration for all the participants in electric power market and its characteristics are related to both market mechanism and variation in the behaviors of market participants. It is necessary to build a real-time price forecasting model with adaptive capability; and because there are outliers in the price data, they should be detected and filtrated in training the forecasting model by regression method. In view of these points, this paper presents an electricity price forecasting method based on accurate on-line support vector regression (AOSVR) and outlier detection. Numerical testing results show that the method is effective in forecasting the electricity prices in electric power market.
文摘An electromagnet design system is developed using Visual C++ language and OpenGL technology to visualize parametric 3D model. The system consists of primary design,optimization design, dynamic and static characteristics, and visual simulation. All empirical parameters and curves used in design process are stored in database. Through human-computer interactions, an electromagnetic system can be designed conveniently with the results and characteristics curves displayed in graphic model. Using this system can greatly shorten the process of product design, and the results satisfy technical requirements.
