Along the geodesic we calculate the interference phase of the mass neutrinos in some special cases. Because of the rotation of the mass resource which induces the gravitational field, the angular momentum per unit mas...Along the geodesic we calculate the interference phase of the mass neutrinos in some special cases. Because of the rotation of the mass resource which induces the gravitational field, the angular momentum per unit mass, a, has a contribution to the phase, which is different from the case in Schwarzschild space-time.展开更多
In this paper, we propose a protocol where one can realize reestablishment of an unknown state and its orthogonal complement state with a certain probability. In the first stage of the protocol, teleportation is perfo...In this paper, we propose a protocol where one can realize reestablishment of an unknown state and its orthogonal complement state with a certain probability. In the first stage of the protocol, teleportation is performed between Alice (a sender) and Bob (a receiver) through a nonmaximally entangled quantum channel. In the process of teleportation, Alice performs nonmaximally entangled state measurement. In the second stage of the protocol, Victor (a state preparer) disentangles leftover nonmaximally entangled states by a single-particle measurement. With the assistance of Victor Alice can reestablish the original state or produce its orthogonal state.展开更多
The effects of the variations in fiber length,fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs).The inf...The effects of the variations in fiber length,fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs).The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated.By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port,the pump power dependent on MWS becomes independent of pumped EDF length.This is a novel phenomenon that hasn’t been reported up to now,and should be helpful to SFS fabrication and theory analysis.By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ~20 channels (from 1 542 nm to 1 559 nm) is got.The MWFS has a channel spacing of ~0.8 nm which satisfies ITU-standard.The intensity fluctuation among channels is less than 0.5 dB,and the extinction ratio of all channels is above 14 dB.This kind of MWFS should be useful to wavelength division multiplexing systems.展开更多
In the research of using Radial Basis Function Neural Network (RBF NN) forecasting nonlinear time series, we investigate how the different clusterings affect the process of learning and forecasting. We find that k-mea...In the research of using Radial Basis Function Neural Network (RBF NN) forecasting nonlinear time series, we investigate how the different clusterings affect the process of learning and forecasting. We find that k-means clustering is very suitable. In order to increase the precision we introduce a nonlinear feedback term to escape from the local minima of energy, then we use the model to forecast the nonlinear time series which are produced by Mackey-Glass equation and stocks. By selecting the k-means clustering and the suitable feedback term, much better forecasting results are obtained.展开更多
Employing a fiber Fabry-Perot (FFP) interferometer has been considered as a triangle notch filter to demodulate the wavelength of fiber Bragg grating (FBG) sensor.The single parameter of strain has been demodulated,an...Employing a fiber Fabry-Perot (FFP) interferometer has been considered as a triangle notch filter to demodulate the wavelength of fiber Bragg grating (FBG) sensor.The single parameter of strain has been demodulated,and the cross-sensitivity influence of temperature has been eliminated.The principle of this method is simple and easy to be implemented,and has been used to design a 30 t fiber grating weightbridge successfully.The maximal temperature drift error of the weightbridge is 4 με,which means that the full scale error is 8‰. The result reveals that the accuracy is high enough to be used in measurement.展开更多
The microscopic theory of the blue phases of chiral liquid crystal is proposed. Beginning with the potential between two molecules, by using the cell model of liquid, applying statistical physical method, the distribu...The microscopic theory of the blue phases of chiral liquid crystal is proposed. Beginning with the potential between two molecules, by using the cell model of liquid, applying statistical physical method, the distribution function and the free energy of the system are obtained. By using variational approach and zero-order approximation, the differential equation that the order parameter tensor of the blue phase can satisfy is obtained. Then we change the differential equation to the eigenequation problem in quantum mechanics. Considering the symmetry of the blue phases,the order parameter tensors of blue phases Ⅰ and Ⅱ can be made up of the eigenvectors. Our results are the same as the results of Ginzberg-Landau's phenomenological theory. The parameters in the order parameter tensors that we calculate in the located system are close to the predecessors' results.展开更多
The importance of cosmological constant for the cosmological models is given. The variations of the cosmological model for parameters and were discussed respectively. Near , the cosmological model is unstable with t...The importance of cosmological constant for the cosmological models is given. The variations of the cosmological model for parameters and were discussed respectively. Near , the cosmological model is unstable with the change of , and near , the cosmological model is unstable with the change of . So when we consider the stable cosmological model, we must consider the nonzero cosmological constant.展开更多
The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the fieldemission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results sho...The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the fieldemission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results show thatRE solution can form cerium oxide/hydroxides precipitation in the pores of the anodized coating at the beginning ofsealing. At the same time, the spherical deposits formed on the surface of the anodized coating created a barrierto the precipitation of RE solution in the pores. When the pore-structured anodizing film is covered all with thespherical deposits, RE conversion coating will form on the surface of the anodized coating. The reaction of thecoating formation was investigated by employing cyclic voltammetry. The results indicate that accelerator H2O2 actsas the source of O2 by carrying chemical reaction in course of coating formation. In the mean time, it maybe carrieselectrochemical reaction to generate alkaline condition to accelerate the coating formation. The porous structure ofthe film is beneficial to the precipitation of the cerium hydroxides film.展开更多
The structure and single-particle motion of a two-dimensional dusty plasma have been investigated. Pair correlation function, mean square displacement, velocity autocorrelation function, and the corresponding spectrum...The structure and single-particle motion of a two-dimensional dusty plasma have been investigated. Pair correlation function, mean square displacement, velocity autocorrelation function, and the corresponding spectrum function have been computed by molecular dynamical simulation. The results show that the coagulation of a two-dimensional dusty plasma system is strongly affected by particle density and temperature, which are discussed in details.展开更多
Two compounds, Dy_2(WO_4)_3 and GdY(WO_4)_3, were synthesized by using thestandard solid state reaction technique. The crystal structure was determined by powder X-raydiffraction and Rietveld refinement method. It is ...Two compounds, Dy_2(WO_4)_3 and GdY(WO_4)_3, were synthesized by using thestandard solid state reaction technique. The crystal structure was determined by powder X-raydiffraction and Rietveld refinement method. It is found that both compounds have Eu_2(WO_4)_3-typemonoclinic structure, with space group C 2/c, Z = 4. The unit cell parameters of Dy_2(WO_4)_3 are a= 0.75981(1) nm, b = 1.13220(1) nm, c = 1.13254(1) nm, and beta = 109.8001(3) deg, and those ofGdY(WO_4)_3 arc a = 0.76175(1) nm, b = 1.13543(1) nm, c = 1.13496(2) nm, and beta = 109.8015(13)deg. Each W atom has four oxygen nearest neighbors, while each rare-earth atom is surrounded byeight oxygen atoms. WO_4 tetrahedra share their four vertices with REO_8 (RE = Dy, Gd, or Y)trigondodecahedra and some REO_8 trigondodecahedra share an edge with each other. The phasetransition and the magnetic properties were investigated by differential thermal analysis (DTA) anddc superconducting quantum interference device (SQUID) magnetometer.展开更多
Magnetic excitations for Ba isotopes are discussed within the nucleon-pair shell model truncated in the SD subspace. With the SD pair determined by a surface- interaction, M1 transitions for are well fitted. The M1 a...Magnetic excitations for Ba isotopes are discussed within the nucleon-pair shell model truncated in the SD subspace. With the SD pair determined by a surface- interaction, M1 transitions for are well fitted. The M1 and M3 transitions for and are also predicted. It is shown that the statement, the collective magnetic properties are due to the orbital motion of nucleons, is approximately valid.展开更多
Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the film was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results sho...Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the film was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the coating remained passivity at the potential range from the open circuit potential (-780 mV) to -250 mV in NaCl solution. When the potential exceeded -200 mV, corrosion reaction happened on the coating, the results of EIS analysis was consistent with the results of polarization curves.展开更多
La 0.7 Sr 0.3 Fe x Mn 1- x O 3 compounds (0 05≤ x ≤0 18) were prepared by the sol gel technique. The effects of Fe doping on the magnetic properties, conductivity and magnetoresistance for L...La 0.7 Sr 0.3 Fe x Mn 1- x O 3 compounds (0 05≤ x ≤0 18) were prepared by the sol gel technique. The effects of Fe doping on the magnetic properties, conductivity and magnetoresistance for La 0.7 Sr 0.3 MnO 3 was investigated. Experimental results indicate that the Fe doping leads to a decrease in the ferromagnetic ordering temperature, an increase in the resistance and magnetoresistance effect. For samples of x =0 05 and x =0 08 two peaks are observed in their ρ T curve. Magnetic resistivity ( MR ) of La 0.7 Sr 0.3 Fe 0.08 Mn 0.92 O 3 sample is capable of reaching 18%(8×10 5A·m -1 , 293 K). At x ≥0 1, metal insulator (M I) transition temperature ( T p) is lower than ferromagnetic Curie temperature ( T C) by about 50~80 K.展开更多
The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ion...The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ions. The behaviors of co-pump and counter-pump methods are contrasted. Dependence of output power on input pump power, output reflectivity, operating wavelength and active fiber length is simulated, respectively. High conversion efficiency Er/Yb laser output is obtained in simulations and experiments.展开更多
The oxide ZrW_2O_8 displays unusual property of isotropic negative thermalexpansion in a large wide temperature range, which makes it have a number of important potentialapplications. The cubic Zr_(1-x)Hf_xW_2O_8 (x v...The oxide ZrW_2O_8 displays unusual property of isotropic negative thermalexpansion in a large wide temperature range, which makes it have a number of important potentialapplications. The cubic Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3, 0.5, 0.7, and 1.0) were synthesized bystandard solid state reaction technique. The high and low temperature X-ray diffraction analysisindicate that the substitution of the Hf^(4+) for Zr^(4+) only leads to reducing the latticeconstants, and the changes of negative thermal expansion coefficients are not obvious. The linearexpansion coefficients of Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3, 0.5, 0.7, and 1.0) are about -6 X 10^(-6) K^(-1) in the temperature range of 298 to 973 K, while that of Zr_(0.5)Hf_(0.5)W_2O_8 is -9.6X 10^(-6) K_(-1) from 83 to 298 K. The phase transition temperatures from alpha-ZrW_2O_8 tobeta-ZrW_2O_8 structure were also determined by X-ray diffraction method. Thermogravimetric analysis(TGA) exhibits that Zr_(1-x)Hf_xW_2O_8 is not hygroscopic in air.展开更多
The gravitational effects (precession of charge-less particles and deflection of light) in the gravitational field of a celestial body with magnetic charge and moment (CM) are investigated. We found that the magnetic...The gravitational effects (precession of charge-less particles and deflection of light) in the gravitational field of a celestial body with magnetic charge and moment (CM) are investigated. We found that the magnetic charge always weakens the pure Schwarzschild effects, while the magnetic dipole moment deforms the effects in a more complicated way.展开更多
The crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) has been redetermined with the single -crystal sample collected from Bayan Obo, Inner Mongolia, China. The chemical formula of the sample is Ce4F...The crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) has been redetermined with the single -crystal sample collected from Bayan Obo, Inner Mongolia, China. The chemical formula of the sample is Ce4Fe2Ti3Si4O22. The crystals are monoclinic with the unit cell parameters a = 13.4656(15) ?, b = 5.7356(6) ?, c = 11.0977(12) ?, β= 100.636(2)o, V = 842.39 (16) ?3 and Z = 2. The structures of Ti- and Fe2+-rich chevkinite-(Ce) were refined with space groups P21/a and C2/m. Least-squares refinement results show that both structural models of Ti- and Fe2+-rich chevkinite-(Ce) are very good, R[F2>2σ(F2)] =0.027 with P21/a and R[F2>2σ(F2)] =0.021 with C2/m. In order to illustrate the relationship between the two space groups P21/a and C2/m, the distribution of diffraction intensities was inspected. Pseudo extinction was found, i.e., reflections with h+k=2n are systematically strong, while those with h+k=2n+1 are weak. By neglecting the systematically weak (h+k=2n+1) reflections the space group becomes C2/m. There is a mirror plane in the C2/m perpendicular to the b axis. However, oxygen atoms in the P21/a model are of a symmetrical relationship with the corresponding pseudo mirror plane. It is concluded that the crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) is a superstructure with the space group of P21/a, which is of pseudo symmetry corresponding to the space group C2/m.展开更多
The concept and analysis method of photonic crystals and band gaps are introduced into one-dimensional(1D) ordered mesoporous materials. MCM-41 type of materials are treated theoretically as photonic crystals. The for...The concept and analysis method of photonic crystals and band gaps are introduced into one-dimensional(1D) ordered mesoporous materials. MCM-41 type of materials are treated theoretically as photonic crystals. The formation of band gaps is exhibited and confirmed by a calculation of transfer matrix technique. PBG was found around 9-42 nm in soft X-ray region. The photonic band-gap was predicted to be dependent on incident direction, pore size and lattice constant. The mesoporous materials with different pore sizes and different lattice constants have different band-gap widths.展开更多
Based on the idea of tilting a photoelectric conversion device,the monocrystalline silicon p-n junction device was tilted to make light incident upon the device at an angle of 45° with the normal of the device su...Based on the idea of tilting a photoelectric conversion device,the monocrystalline silicon p-n junction device was tilted to make light incident upon the device at an angle of 45° with the normal of the device surface,resulting in infrared multiple-internal-reflection inside the device.The internal reflection leads to path length increase of infrared light,making the enhancement of infrared absorption of the device.An increase of 11% in energy conversion efficiency has been obtained through tilting the device.展开更多
文摘Along the geodesic we calculate the interference phase of the mass neutrinos in some special cases. Because of the rotation of the mass resource which induces the gravitational field, the angular momentum per unit mass, a, has a contribution to the phase, which is different from the case in Schwarzschild space-time.
文摘In this paper, we propose a protocol where one can realize reestablishment of an unknown state and its orthogonal complement state with a certain probability. In the first stage of the protocol, teleportation is performed between Alice (a sender) and Bob (a receiver) through a nonmaximally entangled quantum channel. In the process of teleportation, Alice performs nonmaximally entangled state measurement. In the second stage of the protocol, Victor (a state preparer) disentangles leftover nonmaximally entangled states by a single-particle measurement. With the assistance of Victor Alice can reestablish the original state or produce its orthogonal state.
文摘The effects of the variations in fiber length,fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs).The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated.By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port,the pump power dependent on MWS becomes independent of pumped EDF length.This is a novel phenomenon that hasn’t been reported up to now,and should be helpful to SFS fabrication and theory analysis.By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ~20 channels (from 1 542 nm to 1 559 nm) is got.The MWFS has a channel spacing of ~0.8 nm which satisfies ITU-standard.The intensity fluctuation among channels is less than 0.5 dB,and the extinction ratio of all channels is above 14 dB.This kind of MWFS should be useful to wavelength division multiplexing systems.
文摘In the research of using Radial Basis Function Neural Network (RBF NN) forecasting nonlinear time series, we investigate how the different clusterings affect the process of learning and forecasting. We find that k-means clustering is very suitable. In order to increase the precision we introduce a nonlinear feedback term to escape from the local minima of energy, then we use the model to forecast the nonlinear time series which are produced by Mackey-Glass equation and stocks. By selecting the k-means clustering and the suitable feedback term, much better forecasting results are obtained.
文摘Employing a fiber Fabry-Perot (FFP) interferometer has been considered as a triangle notch filter to demodulate the wavelength of fiber Bragg grating (FBG) sensor.The single parameter of strain has been demodulated,and the cross-sensitivity influence of temperature has been eliminated.The principle of this method is simple and easy to be implemented,and has been used to design a 30 t fiber grating weightbridge successfully.The maximal temperature drift error of the weightbridge is 4 με,which means that the full scale error is 8‰. The result reveals that the accuracy is high enough to be used in measurement.
文摘The microscopic theory of the blue phases of chiral liquid crystal is proposed. Beginning with the potential between two molecules, by using the cell model of liquid, applying statistical physical method, the distribution function and the free energy of the system are obtained. By using variational approach and zero-order approximation, the differential equation that the order parameter tensor of the blue phase can satisfy is obtained. Then we change the differential equation to the eigenequation problem in quantum mechanics. Considering the symmetry of the blue phases,the order parameter tensors of blue phases Ⅰ and Ⅱ can be made up of the eigenvectors. Our results are the same as the results of Ginzberg-Landau's phenomenological theory. The parameters in the order parameter tensors that we calculate in the located system are close to the predecessors' results.
文摘The importance of cosmological constant for the cosmological models is given. The variations of the cosmological model for parameters and were discussed respectively. Near , the cosmological model is unstable with the change of , and near , the cosmological model is unstable with the change of . So when we consider the stable cosmological model, we must consider the nonzero cosmological constant.
基金This work has been carried out with the support of The Chinese Postdoctoral Science FundThe Special Funds for the Major State Basic Research Projects G19990650.
文摘The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the fieldemission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results show thatRE solution can form cerium oxide/hydroxides precipitation in the pores of the anodized coating at the beginning ofsealing. At the same time, the spherical deposits formed on the surface of the anodized coating created a barrierto the precipitation of RE solution in the pores. When the pore-structured anodizing film is covered all with thespherical deposits, RE conversion coating will form on the surface of the anodized coating. The reaction of thecoating formation was investigated by employing cyclic voltammetry. The results indicate that accelerator H2O2 actsas the source of O2 by carrying chemical reaction in course of coating formation. In the mean time, it maybe carrieselectrochemical reaction to generate alkaline condition to accelerate the coating formation. The porous structure ofthe film is beneficial to the precipitation of the cerium hydroxides film.
文摘The structure and single-particle motion of a two-dimensional dusty plasma have been investigated. Pair correlation function, mean square displacement, velocity autocorrelation function, and the corresponding spectrum function have been computed by molecular dynamical simulation. The results show that the coagulation of a two-dimensional dusty plasma system is strongly affected by particle density and temperature, which are discussed in details.
文摘Two compounds, Dy_2(WO_4)_3 and GdY(WO_4)_3, were synthesized by using thestandard solid state reaction technique. The crystal structure was determined by powder X-raydiffraction and Rietveld refinement method. It is found that both compounds have Eu_2(WO_4)_3-typemonoclinic structure, with space group C 2/c, Z = 4. The unit cell parameters of Dy_2(WO_4)_3 are a= 0.75981(1) nm, b = 1.13220(1) nm, c = 1.13254(1) nm, and beta = 109.8001(3) deg, and those ofGdY(WO_4)_3 arc a = 0.76175(1) nm, b = 1.13543(1) nm, c = 1.13496(2) nm, and beta = 109.8015(13)deg. Each W atom has four oxygen nearest neighbors, while each rare-earth atom is surrounded byeight oxygen atoms. WO_4 tetrahedra share their four vertices with REO_8 (RE = Dy, Gd, or Y)trigondodecahedra and some REO_8 trigondodecahedra share an edge with each other. The phasetransition and the magnetic properties were investigated by differential thermal analysis (DTA) anddc superconducting quantum interference device (SQUID) magnetometer.
文摘Magnetic excitations for Ba isotopes are discussed within the nucleon-pair shell model truncated in the SD subspace. With the SD pair determined by a surface- interaction, M1 transitions for are well fitted. The M1 and M3 transitions for and are also predicted. It is shown that the statement, the collective magnetic properties are due to the orbital motion of nucleons, is approximately valid.
基金This work has been carried out with the support of the Chinese Postdoctoral Science Fund and the Special Funds for the Major State Basic Research Projects G19990650.
文摘Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the film was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the coating remained passivity at the potential range from the open circuit potential (-780 mV) to -250 mV in NaCl solution. When the potential exceeded -200 mV, corrosion reaction happened on the coating, the results of EIS analysis was consistent with the results of polarization curves.
文摘La 0.7 Sr 0.3 Fe x Mn 1- x O 3 compounds (0 05≤ x ≤0 18) were prepared by the sol gel technique. The effects of Fe doping on the magnetic properties, conductivity and magnetoresistance for La 0.7 Sr 0.3 MnO 3 was investigated. Experimental results indicate that the Fe doping leads to a decrease in the ferromagnetic ordering temperature, an increase in the resistance and magnetoresistance effect. For samples of x =0 05 and x =0 08 two peaks are observed in their ρ T curve. Magnetic resistivity ( MR ) of La 0.7 Sr 0.3 Fe 0.08 Mn 0.92 O 3 sample is capable of reaching 18%(8×10 5A·m -1 , 293 K). At x ≥0 1, metal insulator (M I) transition temperature ( T p) is lower than ferromagnetic Curie temperature ( T C) by about 50~80 K.
基金National Natural Science Foundation of China ( 60137010 ) Tianjin Key Project Foundation of China(033183611)
文摘The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ions. The behaviors of co-pump and counter-pump methods are contrasted. Dependence of output power on input pump power, output reflectivity, operating wavelength and active fiber length is simulated, respectively. High conversion efficiency Er/Yb laser output is obtained in simulations and experiments.
基金This project is financially supported by the National Natural Science Foundation of China (No. 50002001) the Natural Science Foundation of Yunnan Province (No. 2000E0006Q)
文摘The oxide ZrW_2O_8 displays unusual property of isotropic negative thermalexpansion in a large wide temperature range, which makes it have a number of important potentialapplications. The cubic Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3, 0.5, 0.7, and 1.0) were synthesized bystandard solid state reaction technique. The high and low temperature X-ray diffraction analysisindicate that the substitution of the Hf^(4+) for Zr^(4+) only leads to reducing the latticeconstants, and the changes of negative thermal expansion coefficients are not obvious. The linearexpansion coefficients of Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3, 0.5, 0.7, and 1.0) are about -6 X 10^(-6) K^(-1) in the temperature range of 298 to 973 K, while that of Zr_(0.5)Hf_(0.5)W_2O_8 is -9.6X 10^(-6) K_(-1) from 83 to 298 K. The phase transition temperatures from alpha-ZrW_2O_8 tobeta-ZrW_2O_8 structure were also determined by X-ray diffraction method. Thermogravimetric analysis(TGA) exhibits that Zr_(1-x)Hf_xW_2O_8 is not hygroscopic in air.
文摘The gravitational effects (precession of charge-less particles and deflection of light) in the gravitational field of a celestial body with magnetic charge and moment (CM) are investigated. We found that the magnetic charge always weakens the pure Schwarzschild effects, while the magnetic dipole moment deforms the effects in a more complicated way.
基金supported by the National Natural Science Foundation of China(Grant 40472030)
文摘The crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) has been redetermined with the single -crystal sample collected from Bayan Obo, Inner Mongolia, China. The chemical formula of the sample is Ce4Fe2Ti3Si4O22. The crystals are monoclinic with the unit cell parameters a = 13.4656(15) ?, b = 5.7356(6) ?, c = 11.0977(12) ?, β= 100.636(2)o, V = 842.39 (16) ?3 and Z = 2. The structures of Ti- and Fe2+-rich chevkinite-(Ce) were refined with space groups P21/a and C2/m. Least-squares refinement results show that both structural models of Ti- and Fe2+-rich chevkinite-(Ce) are very good, R[F2>2σ(F2)] =0.027 with P21/a and R[F2>2σ(F2)] =0.021 with C2/m. In order to illustrate the relationship between the two space groups P21/a and C2/m, the distribution of diffraction intensities was inspected. Pseudo extinction was found, i.e., reflections with h+k=2n are systematically strong, while those with h+k=2n+1 are weak. By neglecting the systematically weak (h+k=2n+1) reflections the space group becomes C2/m. There is a mirror plane in the C2/m perpendicular to the b axis. However, oxygen atoms in the P21/a model are of a symmetrical relationship with the corresponding pseudo mirror plane. It is concluded that the crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) is a superstructure with the space group of P21/a, which is of pseudo symmetry corresponding to the space group C2/m.
文摘The concept and analysis method of photonic crystals and band gaps are introduced into one-dimensional(1D) ordered mesoporous materials. MCM-41 type of materials are treated theoretically as photonic crystals. The formation of band gaps is exhibited and confirmed by a calculation of transfer matrix technique. PBG was found around 9-42 nm in soft X-ray region. The photonic band-gap was predicted to be dependent on incident direction, pore size and lattice constant. The mesoporous materials with different pore sizes and different lattice constants have different band-gap widths.
文摘Based on the idea of tilting a photoelectric conversion device,the monocrystalline silicon p-n junction device was tilted to make light incident upon the device at an angle of 45° with the normal of the device surface,resulting in infrared multiple-internal-reflection inside the device.The internal reflection leads to path length increase of infrared light,making the enhancement of infrared absorption of the device.An increase of 11% in energy conversion efficiency has been obtained through tilting the device.