Fe/C multilayer thin films were deposited by magnetron sputtering. Small angle X-ray diffraction measurements show very well periodicity of the samples. The modulation period determined from a modified Bragg equation ...Fe/C multilayer thin films were deposited by magnetron sputtering. Small angle X-ray diffraction measurements show very well periodicity of the samples. The modulation period determined from a modified Bragg equation agrees well with that determined from deposition rate. The interfacial roughness parameter ξof several samples calculated by X-ray diffraction is between 3.5(?) and 5.6(?).展开更多
In order to further investigate the surface flashover mechanism in vacuum, the surface flashover and electric field distribution of multilayer organic insulation structure are studied and developed based on the previo...In order to further investigate the surface flashover mechanism in vacuum, the surface flashover and electric field distribution of multilayer organic insulation structure are studied and developed based on the previous studies. The samples of multilayer organic insulation structure are prepared by inserting multilayer organic composite material with different relative permittivity between the electrode and the dielectric. Two multilayer organic insulation structures are prepared in this study. One is the cylindrical samples, the other is 45° samples. The impulse (1.2/50 μs) and DC flashover voltages in vacuum are tested, and the electric field distributions of two insulation structures are analyzed by ANSYS. It is found that these two insulation structure could effectively improve the surface flashover performance in vacuum. The results indicate that the highest impulse first flashover voltage of cylindrical samples reaches 65 kV and increases by 25% under im- pulse voltage. The highest first flashover voltage of /c samples reaches 81 kV and increases by 32% under impulse voltage. The results of electric field simulation demonstrate that different mechanisms exist between 45° insulation structure and cylindrical structure.展开更多
An indoor location system based on multilayer artificial neural network（ANN） with area division is proposed.The characteristics of recorded signal strength（RSS）,or signal to noise ratio（SNR） from each available ...An indoor location system based on multilayer artificial neural network（ANN） with area division is proposed.The characteristics of recorded signal strength（RSS）,or signal to noise ratio（SNR） from each available access points（APs）,are utilized to establish the radio map in the off-line phase.And in the on-line phase,the two or three dimensional coordinates of mobile terminals（MTs） are estimated according to the similarity between the new recorded RSS or SNR and fingerprints pre-stored in radio map.Although the feed-forward ANN with three layers is sufficient to describe any nonlinear mapping relationship between inputs and outputs with finite discontinuous points,the efficient inputs for better training performances are difficult to be determined because of complex and dynamic indoor environment.Then,the discussion of distance relativity for different signal characteristics and optimal strategies for multi-mode phenomenon avoidance is presented.And also,the feasibility and effectiveness of this method are verified based on the experimental comparison with normal ANN without area division,K-nearest neighbor（KNN） and probability methods in typical office environment.展开更多
The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity funct...The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.展开更多
通过流变特性和3D打印特性评估,筛选叶黄素负载层和空载层乳液凝胶的制备参数,运用双喷头3D打印技术将叶黄素负载层与空载层间隔交错打印,构建不同间隔多层结构的3D打印凝胶体系,探究间隔多层结构的间隔层数和空载层定位对叶黄素的释放...通过流变特性和3D打印特性评估,筛选叶黄素负载层和空载层乳液凝胶的制备参数,运用双喷头3D打印技术将叶黄素负载层与空载层间隔交错打印,构建不同间隔多层结构的3D打印凝胶体系,探究间隔多层结构的间隔层数和空载层定位对叶黄素的释放特性和生物可及性的影响。结果表明,通过提升油相体积分数、分离乳清蛋白(Whey Protein Isolate,WPI)浓度以及叶黄素载量,可以有效地提高叶黄素乳液凝胶的表观黏度、储能模量和损耗模量,同时降低蠕变恢复应变,增强叶黄素乳液凝胶的黏弹性和抵抗形变的能力,从而显著提升了叶黄素乳液凝胶的打印精确度和稳定性;当油相体积分数为15%、WPI浓度为10%和叶黄素载量为1.5%时,叶黄素乳液凝胶的3D打印效果最佳,打印精确性和稳定性分别为96.94%和97.60%。经体外模拟消化发现,间隔多层结构设计可有效改变叶黄素的释放行为,显著降低了叶黄素在胃消化阶段的释放率,从21.61%最低降至7.26%,使叶黄素在肠消化阶段表现出一定的时滞性,并显著提高叶黄素的生物可及性,最高达到了47.97%。本研究将为解决叶黄素生物可及性低的问题和运载工具的设计提供新的思路和理论依据。展开更多
文摘Fe/C multilayer thin films were deposited by magnetron sputtering. Small angle X-ray diffraction measurements show very well periodicity of the samples. The modulation period determined from a modified Bragg equation agrees well with that determined from deposition rate. The interfacial roughness parameter ξof several samples calculated by X-ray diffraction is between 3.5(?) and 5.6(?).
基金Project supported by National Science Fund for Outstanding Young Scholars of China (50625721)National Basic Research Program of China (973 Program) (2011CB 209404)
文摘In order to further investigate the surface flashover mechanism in vacuum, the surface flashover and electric field distribution of multilayer organic insulation structure are studied and developed based on the previous studies. The samples of multilayer organic insulation structure are prepared by inserting multilayer organic composite material with different relative permittivity between the electrode and the dielectric. Two multilayer organic insulation structures are prepared in this study. One is the cylindrical samples, the other is 45° samples. The impulse (1.2/50 μs) and DC flashover voltages in vacuum are tested, and the electric field distributions of two insulation structures are analyzed by ANSYS. It is found that these two insulation structure could effectively improve the surface flashover performance in vacuum. The results indicate that the highest impulse first flashover voltage of cylindrical samples reaches 65 kV and increases by 25% under im- pulse voltage. The highest first flashover voltage of /c samples reaches 81 kV and increases by 32% under impulse voltage. The results of electric field simulation demonstrate that different mechanisms exist between 45° insulation structure and cylindrical structure.
基金supported by the National High Technology Research and Development Program of China (863 Program)(2008AA12Z305)
文摘An indoor location system based on multilayer artificial neural network（ANN） with area division is proposed.The characteristics of recorded signal strength（RSS）,or signal to noise ratio（SNR） from each available access points（APs）,are utilized to establish the radio map in the off-line phase.And in the on-line phase,the two or three dimensional coordinates of mobile terminals（MTs） are estimated according to the similarity between the new recorded RSS or SNR and fingerprints pre-stored in radio map.Although the feed-forward ANN with three layers is sufficient to describe any nonlinear mapping relationship between inputs and outputs with finite discontinuous points,the efficient inputs for better training performances are difficult to be determined because of complex and dynamic indoor environment.Then,the discussion of distance relativity for different signal characteristics and optimal strategies for multi-mode phenomenon avoidance is presented.And also,the feasibility and effectiveness of this method are verified based on the experimental comparison with normal ANN without area division,K-nearest neighbor（KNN） and probability methods in typical office environment.
文摘The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.
文摘通过流变特性和3D打印特性评估,筛选叶黄素负载层和空载层乳液凝胶的制备参数,运用双喷头3D打印技术将叶黄素负载层与空载层间隔交错打印,构建不同间隔多层结构的3D打印凝胶体系,探究间隔多层结构的间隔层数和空载层定位对叶黄素的释放特性和生物可及性的影响。结果表明,通过提升油相体积分数、分离乳清蛋白(Whey Protein Isolate,WPI)浓度以及叶黄素载量,可以有效地提高叶黄素乳液凝胶的表观黏度、储能模量和损耗模量,同时降低蠕变恢复应变,增强叶黄素乳液凝胶的黏弹性和抵抗形变的能力,从而显著提升了叶黄素乳液凝胶的打印精确度和稳定性;当油相体积分数为15%、WPI浓度为10%和叶黄素载量为1.5%时,叶黄素乳液凝胶的3D打印效果最佳,打印精确性和稳定性分别为96.94%和97.60%。经体外模拟消化发现,间隔多层结构设计可有效改变叶黄素的释放行为,显著降低了叶黄素在胃消化阶段的释放率,从21.61%最低降至7.26%,使叶黄素在肠消化阶段表现出一定的时滞性,并显著提高叶黄素的生物可及性,最高达到了47.97%。本研究将为解决叶黄素生物可及性低的问题和运载工具的设计提供新的思路和理论依据。
