Numerical simulation of the electrical field distribution helps in-depth understanding of the mechanisms behind the responses and the benefits of the high voltage pulse comminution. The COMSOL Multiphysics package was...Numerical simulation of the electrical field distribution helps in-depth understanding of the mechanisms behind the responses and the benefits of the high voltage pulse comminution. The COMSOL Multiphysics package was used to numerically simulate the effect of ore compositions in this study. Regarding phosphate ore particles shape and composition, the effects of mineral composition, particle size, particle shape and electrodes distance were investigated on the electrical field intensity and distribution. The results show that the induced electrical field is significantly dependent on the electrical properties of minerals,the feed particle size and the location of conductive minerals in ores. The angle of material contact surface with the discharge electrode is also an important factor in the intensity of electrical field. Moreover,it is found that the specific liberation effect at the disintegration of phosphate ore by electrical pulses is due to the locality of the electrical field at the interface of mineral components of the phosphate ore aggregates with different permittivities. However, the intensity of the electrical field increases with sharpening the contact angle. Besides, the electrical discharge in the samples is converted to the electrohydraulic discharge across the surrounding water by changing the distance between the discharge electrode and sample surface.展开更多
A investigation of the properties of the bound states of D^- centers confined in a parabolic quantum dot has been performed for the case with the presence of a perpendicular magnetic field. Calculations are carried ou...A investigation of the properties of the bound states of D^- centers confined in a parabolic quantum dot has been performed for the case with the presence of a perpendicular magnetic field. Calculations are carried out by using the method of numerical diagonalization of Hamiltonian matrix within the effective-mass approximation. The binding energies of the ground and some bound-excited states are obtained as a function of the applied magnetic field strength. Detailed calculations of the binding energies for a number of low-lying states show that for field strength less than B = 2.1 T, the D center confined in a quantum dot possesses two bound states, for 2.1 〈 B 〈 2.4 T, there exist three bound states, etc. Further relevant characteristics of the D- center quantum dots in magnetic fields are provided.展开更多
Pulsed electric field is an innovative method for non-thermal food processing. The effects of pulsed electric field on cell disintegration and mass transfer in sugar beet were studied. Sugar beet slices were treated b...Pulsed electric field is an innovative method for non-thermal food processing. The effects of pulsed electric field on cell disintegration and mass transfer in sugar beet were studied. Sugar beet slices were treated by various Field strengths （0.5-6 kV cm^-1）, capacity of capacitors （0.5, 8 and 32 μF） and pulse numbers （1-100 pulses）. The cell disintegration index and energy input for each treated sample was evaluated. The results showed that the cell membrane of PEF （Pulsed Electric Field） treated samples using 2 kV cm^-1, 8 μF after 20 pulses, and 3 kV cm1, 8 μF after 10 pulses were rapidly disintegrated in less than 1 min. Most important parameters during cell permeabilization were the total energy input followed by field strength. Energy efficiency index was defined as cell disintegration index per energy input unit. The maximum efficiency index was achieved using 2 kV cm^-1, 8 μF after 5 pulses. Comparison between PEF pretreatment and thermal method showed that large amount of sugar may be extracted after PEF pretreatment using field strength of 2 Kv cm^-1, 8μF in less than 10 min at ambient temperature. In.addition, the consumed energy for thermal treatment was approximately 20 to 50 times more than PEF pretreatment. Optimizing the field conditions in PEF treatment is an important factor to achieve high amount of sugar extraction from sugar beet.展开更多
The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere's Law, and the environm...The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere's Law, and the environmental impact factors of the fields were evaluated. By optimizing the phase sequence, the frequency electric intensity and magnetic field strength can be reduced. Within a distance of 25 m from the center of the transmission line, the power frequency electric intensity and magnetic field strength fall off sharply with the distance increase. Finally, the best phase sequence and the minimum ground clearance of the transmission lines were obtained to meet the requirements of the least impact on envionment.展开更多
this work,the polarization effects of a strongly magnetized quark-gluon plasma are studied at finite temperature.It is found that a background magnetic field can have a strong effect on the photon and dilepton emissio...this work,the polarization effects of a strongly magnetized quark-gluon plasma are studied at finite temperature.It is found that a background magnetic field can have a strong effect on the photon and dilepton emission rates.It affects not only the total rate but also the angular dependence.In particular,the Landau-level quantization leads to a nontrivial momentum dependence of the photon/dilepton anisotropic flow coefficient on transverse momentum.In the case of photon emission,nonzero coefficients v_(n)(with even n)have opposite signs at small and large values of the transverse momentum.Additionally,the v_(n) signs alternate with increasing vn,and their approximate values decrease as 1/n^(2) in magnitude.The anisotropy of dilepton emission is well-pronounced only at large transverse momenta and small invariant masses.The corresponding Un coefficients are of the same magnitude and show a similar sign-alternative pattern with increasing n as in the photon emission.It is proposed that the anisotropy of the photon and dilepton emission may serve as indirect measurements of the magnetic field.展开更多
Experimental and computational methods are used to optimize the electrostatic field for levitating metallic materials.The calculated launch voltage increases linearly with the distance between top and bottom electrode...Experimental and computational methods are used to optimize the electrostatic field for levitating metallic materials.The calculated launch voltage increases linearly with the distance between top and bottom electrodes.The combination of a larger top electrode diameter with a smaller bottom diameter may enhance the levitation ability because the electric field intensity near the levitated sample is strengthened.Top convex and bottom concave electrodes can guarantee good levitation stability but decrease the levitation force.The design of bottom electrode is crucial to attain not only a stable levitation state but also a higher levitation capability.As a measure characterizing the intrinsic levitation ability of various materials,the product of density and diameter of levitated samples can be used to determine the launch voltage for counteracting gravity according to a power relationship.展开更多
文摘Numerical simulation of the electrical field distribution helps in-depth understanding of the mechanisms behind the responses and the benefits of the high voltage pulse comminution. The COMSOL Multiphysics package was used to numerically simulate the effect of ore compositions in this study. Regarding phosphate ore particles shape and composition, the effects of mineral composition, particle size, particle shape and electrodes distance were investigated on the electrical field intensity and distribution. The results show that the induced electrical field is significantly dependent on the electrical properties of minerals,the feed particle size and the location of conductive minerals in ores. The angle of material contact surface with the discharge electrode is also an important factor in the intensity of electrical field. Moreover,it is found that the specific liberation effect at the disintegration of phosphate ore by electrical pulses is due to the locality of the electrical field at the interface of mineral components of the phosphate ore aggregates with different permittivities. However, the intensity of the electrical field increases with sharpening the contact angle. Besides, the electrical discharge in the samples is converted to the electrohydraulic discharge across the surrounding water by changing the distance between the discharge electrode and sample surface.
基金supported by National Natural Science Foundation of China under Grant No. 10775035
文摘A investigation of the properties of the bound states of D^- centers confined in a parabolic quantum dot has been performed for the case with the presence of a perpendicular magnetic field. Calculations are carried out by using the method of numerical diagonalization of Hamiltonian matrix within the effective-mass approximation. The binding energies of the ground and some bound-excited states are obtained as a function of the applied magnetic field strength. Detailed calculations of the binding energies for a number of low-lying states show that for field strength less than B = 2.1 T, the D center confined in a quantum dot possesses two bound states, for 2.1 〈 B 〈 2.4 T, there exist three bound states, etc. Further relevant characteristics of the D- center quantum dots in magnetic fields are provided.
文摘Pulsed electric field is an innovative method for non-thermal food processing. The effects of pulsed electric field on cell disintegration and mass transfer in sugar beet were studied. Sugar beet slices were treated by various Field strengths （0.5-6 kV cm^-1）, capacity of capacitors （0.5, 8 and 32 μF） and pulse numbers （1-100 pulses）. The cell disintegration index and energy input for each treated sample was evaluated. The results showed that the cell membrane of PEF （Pulsed Electric Field） treated samples using 2 kV cm^-1, 8 μF after 20 pulses, and 3 kV cm1, 8 μF after 10 pulses were rapidly disintegrated in less than 1 min. Most important parameters during cell permeabilization were the total energy input followed by field strength. Energy efficiency index was defined as cell disintegration index per energy input unit. The maximum efficiency index was achieved using 2 kV cm^-1, 8 μF after 5 pulses. Comparison between PEF pretreatment and thermal method showed that large amount of sugar may be extracted after PEF pretreatment using field strength of 2 Kv cm^-1, 8μF in less than 10 min at ambient temperature. In.addition, the consumed energy for thermal treatment was approximately 20 to 50 times more than PEF pretreatment. Optimizing the field conditions in PEF treatment is an important factor to achieve high amount of sugar extraction from sugar beet.
文摘The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere's Law, and the environmental impact factors of the fields were evaluated. By optimizing the phase sequence, the frequency electric intensity and magnetic field strength can be reduced. Within a distance of 25 m from the center of the transmission line, the power frequency electric intensity and magnetic field strength fall off sharply with the distance increase. Finally, the best phase sequence and the minimum ground clearance of the transmission lines were obtained to meet the requirements of the least impact on envionment.
文摘this work,the polarization effects of a strongly magnetized quark-gluon plasma are studied at finite temperature.It is found that a background magnetic field can have a strong effect on the photon and dilepton emission rates.It affects not only the total rate but also the angular dependence.In particular,the Landau-level quantization leads to a nontrivial momentum dependence of the photon/dilepton anisotropic flow coefficient on transverse momentum.In the case of photon emission,nonzero coefficients v_(n)(with even n)have opposite signs at small and large values of the transverse momentum.Additionally,the v_(n) signs alternate with increasing vn,and their approximate values decrease as 1/n^(2) in magnitude.The anisotropy of dilepton emission is well-pronounced only at large transverse momenta and small invariant masses.The corresponding Un coefficients are of the same magnitude and show a similar sign-alternative pattern with increasing n as in the photon emission.It is proposed that the anisotropy of the photon and dilepton emission may serve as indirect measurements of the magnetic field.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 50971103 and 51271150)the Program for New Century Excellent Talentsthe NPU Foundation for Fundamental Research
文摘Experimental and computational methods are used to optimize the electrostatic field for levitating metallic materials.The calculated launch voltage increases linearly with the distance between top and bottom electrodes.The combination of a larger top electrode diameter with a smaller bottom diameter may enhance the levitation ability because the electric field intensity near the levitated sample is strengthened.Top convex and bottom concave electrodes can guarantee good levitation stability but decrease the levitation force.The design of bottom electrode is crucial to attain not only a stable levitation state but also a higher levitation capability.As a measure characterizing the intrinsic levitation ability of various materials,the product of density and diameter of levitated samples can be used to determine the launch voltage for counteracting gravity according to a power relationship.
