By employing the dielectric continuum model and Loudon＇s uniaxial crystal model, the interface optical （IO） phonon modes in a freestanding quasi-one-dimensional （Q1D） wurtzite rectangular quantum wire are derived...By employing the dielectric continuum model and Loudon＇s uniaxial crystal model, the interface optical （IO） phonon modes in a freestanding quasi-one-dimensional （Q1D） wurtzite rectangular quantum wire are derived and analyzed. Numerical calculation on a freestanding wurtzite GaN quantum wire is performed. The resulte reveal that the dispersion frequencies of IO modes sensitively depend on the geometric structures of the Q1D wurtzite rectangular quantum wires, the free wave-number kz in z-direction and the dielectric constant of the nonpolar matrix. The degenerating behavior of the IO modes in Q1D wurtzite rectangular quantum wire has been clearly observed in the case of small wave-number kz and Iarge ratio of length to width of the rectangular crossing profile. The limited frequency behaviors of IO modes have been analyzed deeply, and detailed comparisons with those in wurtzite planar quantum wells and cylindrical quantum wires are also done. The present theories can be looked on as a generalization of that in isotropic rectangular quantum wires, and it can naturally reduce to the case of Q1D isotropic quantum wires once the anisotropy of the wurtzite material is ignored.展开更多
Pattern classification is an important field in machine learning; least squares support vector machine (LSSVM) is a powerful tool for pattern classification. A new version of LSSVM, SVD-LSSVM, to save time of selectin...Pattern classification is an important field in machine learning; least squares support vector machine (LSSVM) is a powerful tool for pattern classification. A new version of LSSVM, SVD-LSSVM, to save time of selecting hyper parameters for LSSVM is proposed. SVD-LSSVM is trained through singular value decomposition (SVD) of kernel matrix. Cross validation time of selecting hyper parameters can be saved because a new hyper parameter, singular value contribution rate (SVCR), replaces the penalty factor of LSSVM. Several UCI benchmarking data and the Olive classification problem were used to test SVD-LSSVM. The result showed that SVD-LSSVM has good performance in classification and saves time for cross validation.展开更多
Based on the vector angular spectrum representation of optical beam and the method of stationary phase, the analytical TE and TM terms of vector Gaussian beam have been presented in the far field. By using the local p...Based on the vector angular spectrum representation of optical beam and the method of stationary phase, the analytical TE and TM terms of vector Gaussian beam have been presented in the far field. By using the local polarization matrix, the polarization properties of the TE and TM terms in the far field are investigated, and it is found that the degree of their polarization is only determined by the spatial location. When the source is completely polarized, the TE and TM terms are both completely polarized in the far field. When the source is completely unpolarized, the TE and TM terms in the far field are partially polarized. The whole beam is also partially polarized except on the propagating axis. Moreover, the degrees of polarization of TE and TM terms are both larger than that of the whole beam.展开更多
Using the photon closed orbit theory, the spontaneous emission rate of a polarized atom in a medium between two parallel mirrors is derived and calculated. It is found that the spontaneous emission rate of a polarized...Using the photon closed orbit theory, the spontaneous emission rate of a polarized atom in a medium between two parallel mirrors is derived and calculated. It is found that the spontaneous emission rate of a polarized atom between the mirrors is related to the atomic position and the polarization direction. The results show that in the vicinity of the mirror, the variation of the spontaneous emission rate depends crucially on the atomic polarization direction. With the increase of the polarization angle, the oscillation in the spontaneous emission rate becomes decreased. For the polarization direction parallel to the mirror plane, the oscillation is the greatest; while for the perpendicular polarization direction, the oscillation is nearly vanished. The agreement between our result and the quantum electrodynamics result suggests the correctness of our calculation. This study further verifies that the atomic spontaneous emission process can be effectively controlled by changing the polarization orientation of the atom.展开更多
We study theoretically transport properties of two-dimenslonal electron gases through antiparallel magneticelectric barrier structures. Two kinds of magnetic barrier configurations are employed： one is that the stren...We study theoretically transport properties of two-dimenslonal electron gases through antiparallel magneticelectric barrier structures. Two kinds of magnetic barrier configurations are employed： one is that the strength of the double δ-functlon in opposite directions is equal and the other is that the strength is unequal Similarities and differences of electronic transports are presented. It is found that the transmission and the conductance depend strongly on the shape of the magnetic barrier and the height of the electric harrier. The results indicate that this system does not possess any spin filtering and spin polarization and electron gases can realize perfect resonant tunneling and wave-vector filtering properties. Moreover, the strength of the effect of the inhomogeneous magnetic field on the transport properties is discussed.展开更多
PARASOL(Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) multi-channel and multi-directional polarized data for different aerosol types were compared.The P...PARASOL(Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) multi-channel and multi-directional polarized data for different aerosol types were compared.The PARASOL polarized radiance data at 490 nm,670 nm,and 865 nm increased with aerosol optical thickness(AOT) for fine-mode aerosols;however,the polarized radiances at 490 nm and 670 nm decreased as AOT increased for coarse dust aerosols.Thus,the variation of the polarized radiance with AOT can be used to identify fine or coarse particle-dominated aerosols.Polarized radiances at three wavelengths for fine-and coarse-mode aerosols were analyzed and fitted by linear regression.The slope of the line for 670 nm and 490 nm wavelength pairs is less than 0.35 for dust aerosols.However,the value for fine-mode aerosols is greater than 0.60.The Support Vector Machine method(SVM) based on 12 vector features was used to discriminate clear sky,coarse dust aerosols,fine-mode aerosols,and cloud.Two cases were given and validated by AErosol RObotic NETwork(AERONET) measurements,MODIS(Moderate Resolution Imaging Spectroradiometer) FMF(Fine Mode Fraction at 550 nm) images,PARASOL RGB(Red Green Blue) images,and CALIOP(Cloud-Aerosol Lidar with Orthogonal Polarization) VFM(Vertical Feature Mask) data.展开更多
基金The project supported by the Science and Technology Project of Advanced Academy of Guangzhou City under Grant No. 2060. The author acknowledges the detailed and valuable discussions with Prof. J.J. Shi.
文摘By employing the dielectric continuum model and Loudon＇s uniaxial crystal model, the interface optical （IO） phonon modes in a freestanding quasi-one-dimensional （Q1D） wurtzite rectangular quantum wire are derived and analyzed. Numerical calculation on a freestanding wurtzite GaN quantum wire is performed. The resulte reveal that the dispersion frequencies of IO modes sensitively depend on the geometric structures of the Q1D wurtzite rectangular quantum wires, the free wave-number kz in z-direction and the dielectric constant of the nonpolar matrix. The degenerating behavior of the IO modes in Q1D wurtzite rectangular quantum wire has been clearly observed in the case of small wave-number kz and Iarge ratio of length to width of the rectangular crossing profile. The limited frequency behaviors of IO modes have been analyzed deeply, and detailed comparisons with those in wurtzite planar quantum wells and cylindrical quantum wires are also done. The present theories can be looked on as a generalization of that in isotropic rectangular quantum wires, and it can naturally reduce to the case of Q1D isotropic quantum wires once the anisotropy of the wurtzite material is ignored.
基金Project (No. 20276063) supported by the National Natural Science Foundation of China
文摘Pattern classification is an important field in machine learning; least squares support vector machine (LSSVM) is a powerful tool for pattern classification. A new version of LSSVM, SVD-LSSVM, to save time of selecting hyper parameters for LSSVM is proposed. SVD-LSSVM is trained through singular value decomposition (SVD) of kernel matrix. Cross validation time of selecting hyper parameters can be saved because a new hyper parameter, singular value contribution rate (SVCR), replaces the penalty factor of LSSVM. Several UCI benchmarking data and the Olive classification problem were used to test SVD-LSSVM. The result showed that SVD-LSSVM has good performance in classification and saves time for cross validation.
文摘Based on the vector angular spectrum representation of optical beam and the method of stationary phase, the analytical TE and TM terms of vector Gaussian beam have been presented in the far field. By using the local polarization matrix, the polarization properties of the TE and TM terms in the far field are investigated, and it is found that the degree of their polarization is only determined by the spatial location. When the source is completely polarized, the TE and TM terms are both completely polarized in the far field. When the source is completely unpolarized, the TE and TM terms in the far field are partially polarized. The whole beam is also partially polarized except on the propagating axis. Moreover, the degrees of polarization of TE and TM terms are both larger than that of the whole beam.
基金Supported by National Natural Science Foundation of China under Grant No. 10604045the University Science & Technology Planning Program of Shandong Province under Grant No. J09LA02the Discipline Construction Fund of Ludong University
文摘Using the photon closed orbit theory, the spontaneous emission rate of a polarized atom in a medium between two parallel mirrors is derived and calculated. It is found that the spontaneous emission rate of a polarized atom between the mirrors is related to the atomic position and the polarization direction. The results show that in the vicinity of the mirror, the variation of the spontaneous emission rate depends crucially on the atomic polarization direction. With the increase of the polarization angle, the oscillation in the spontaneous emission rate becomes decreased. For the polarization direction parallel to the mirror plane, the oscillation is the greatest; while for the perpendicular polarization direction, the oscillation is nearly vanished. The agreement between our result and the quantum electrodynamics result suggests the correctness of our calculation. This study further verifies that the atomic spontaneous emission process can be effectively controlled by changing the polarization orientation of the atom.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 19847004 and 10474025.
文摘We study theoretically transport properties of two-dimenslonal electron gases through antiparallel magneticelectric barrier structures. Two kinds of magnetic barrier configurations are employed： one is that the strength of the double δ-functlon in opposite directions is equal and the other is that the strength is unequal Similarities and differences of electronic transports are presented. It is found that the transmission and the conductance depend strongly on the shape of the magnetic barrier and the height of the electric harrier. The results indicate that this system does not possess any spin filtering and spin polarization and electron gases can realize perfect resonant tunneling and wave-vector filtering properties. Moreover, the strength of the effect of the inhomogeneous magnetic field on the transport properties is discussed.
基金supported by the National Basic Research Program of China (Grant Nos.2010CB950804 and 2013CB955801)the Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues (Grant No.XDA05040202)
文摘PARASOL(Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) multi-channel and multi-directional polarized data for different aerosol types were compared.The PARASOL polarized radiance data at 490 nm,670 nm,and 865 nm increased with aerosol optical thickness(AOT) for fine-mode aerosols;however,the polarized radiances at 490 nm and 670 nm decreased as AOT increased for coarse dust aerosols.Thus,the variation of the polarized radiance with AOT can be used to identify fine or coarse particle-dominated aerosols.Polarized radiances at three wavelengths for fine-and coarse-mode aerosols were analyzed and fitted by linear regression.The slope of the line for 670 nm and 490 nm wavelength pairs is less than 0.35 for dust aerosols.However,the value for fine-mode aerosols is greater than 0.60.The Support Vector Machine method(SVM) based on 12 vector features was used to discriminate clear sky,coarse dust aerosols,fine-mode aerosols,and cloud.Two cases were given and validated by AErosol RObotic NETwork(AERONET) measurements,MODIS(Moderate Resolution Imaging Spectroradiometer) FMF(Fine Mode Fraction at 550 nm) images,PARASOL RGB(Red Green Blue) images,and CALIOP(Cloud-Aerosol Lidar with Orthogonal Polarization) VFM(Vertical Feature Mask) data.
