Ever since vortex beams were proposed, they are known for owning phase singularity and carrying orbital angular momentum (OAM). In the past decades, coherent optics developed rapidly. Vortex beams have been extended f...Ever since vortex beams were proposed, they are known for owning phase singularity and carrying orbital angular momentum (OAM). In the past decades, coherent optics developed rapidly. Vortex beams have been extended from fully coherent light to partially coherent light, from scalar light to vector light, from integral topological charge (TC) to fractional TC. Partially coherent vortex beams have attracted tremendous interest due to their hidden correlation singularity and unique propagation properties (e.g., beam shaping, beam rotation and self-reconstruction). Based on the sufficient condition for devising a genuine correlation function of partially coherent beam, partially coherent vortex beams with nonconventional correlation functions (i.e., non-Gaussian correlated Schell-model functions) were introduced recently. This timely review summarizes basic concepts, theoretical models, generation and propagation of partially coherent vortex beams.展开更多
Analyses of the soil moisture evolution trend and the influence of different types of radiation on soil moisture are of great significance to the simulation and prediction of soil moisture.In this paper,soil moisture(...Analyses of the soil moisture evolution trend and the influence of different types of radiation on soil moisture are of great significance to the simulation and prediction of soil moisture.In this paper,soil moisture(2–60 cm) and various radiation data from 2014–2015 at the A’rou superstation were selected.The radiation data include the net radiation(NR),shortwave and longwave radiation(SR and LR).Using adaptive fractal analysis(AFA),the long-range correlation(LRC) of soil moisture and long-range cross correlation(LRCC) between moisture and three types of radiation were analyzed at different timescales and soil depths.The results show that:(1) Persistence of soil moisture and consistency between soil moisture and radiation mutate at 18-d and 6-d timescales,respectively.The timescale variation of soil moisture persistence is mainly related to the influence process of radiation on soil moisture;(2) Both the soil moisture persistence and soil moisture-radiation consistency vary substantially with soil depth.The soil depth variation of soil moisture persistence is related to the influence intensity of radiation;(3) From 2–6 day timescales,LR displays the strongest influence on soil moisture at depths of 2–10 cm through negative feedback of radiation on the soil temperature.The influence intensity decreases with depth from 2–15 cm.Therefore,the soil moisture persistence is weak and increases with depth from 2–15 cm;and(4) At more than 6 day timescales,SR and NR display a stronger influence on the soil moisture persistence at depths of 2–40 cm through positive feedback of radiation on the soil temperature,especially at depths of 2–10 cm.This influence also weakens with depth.The soil moisture persistence at depths of 2–10 cm is the weakest and increases with depth from 2–40 cm.The research results are instructive for determining timescales and soil depths related to soil water in hydrological models.展开更多
The effect of crystallization conditions of poly(butylene succinate)(PBS) component on the crystallization of poly(tetramethylene oxide)(PTMO) component in their segment block copolymer, with a higher PTMO content(PTM...The effect of crystallization conditions of poly(butylene succinate)(PBS) component on the crystallization of poly(tetramethylene oxide)(PTMO) component in their segment block copolymer, with a higher PTMO content(PTMO mass fraction is 67%), was investigated by DSC and temperature-dependent FTIR. It is found that the isothermal crystallization time(tIC) of PBS has an effect on the crystallization behavior of PTMO component. Perturbation correlation move-window two-dimensional(PCMW2 D) correlation analysis and generalized 2 D correlation analysis(2 DIR) were performed to explore the origin of this phenomenon. The PCMW2 D and 2 DIR results show that the correlation intensity peak observed at around 20 ℃ for PTMO is due to the PTMO chains movements forced by the PBS chains folded movements. If tIC of PBS at temperature of 20 ℃ is prolonged, more PTMO components are incorporated in the region between PBS lamellae and the peak at-7.6 ℃(belonging to less-constricted PTMO chains) changes smaller and even disappears, while the peak at-16.3 ℃ belonging to more-constricted PTMO chains gets bigger. A crystallization model was also established in this study. The results of tensile testing showed that tensile strength slightly increased and elongation at break decreased with increasing heat treatment time at 40 ℃.展开更多
基金Authors are thankful for the support of the National Natural Science Foundation of China (Grant Nos. 91750201,1152541 & 11774250 and 11804198),Project of the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Ever since vortex beams were proposed, they are known for owning phase singularity and carrying orbital angular momentum (OAM). In the past decades, coherent optics developed rapidly. Vortex beams have been extended from fully coherent light to partially coherent light, from scalar light to vector light, from integral topological charge (TC) to fractional TC. Partially coherent vortex beams have attracted tremendous interest due to their hidden correlation singularity and unique propagation properties (e.g., beam shaping, beam rotation and self-reconstruction). Based on the sufficient condition for devising a genuine correlation function of partially coherent beam, partially coherent vortex beams with nonconventional correlation functions (i.e., non-Gaussian correlated Schell-model functions) were introduced recently. This timely review summarizes basic concepts, theoretical models, generation and propagation of partially coherent vortex beams.
基金National Key R&D Program of China,No.2017YFB0504102National Natural Science Foundation of China No.41771537.
文摘Analyses of the soil moisture evolution trend and the influence of different types of radiation on soil moisture are of great significance to the simulation and prediction of soil moisture.In this paper,soil moisture(2–60 cm) and various radiation data from 2014–2015 at the A’rou superstation were selected.The radiation data include the net radiation(NR),shortwave and longwave radiation(SR and LR).Using adaptive fractal analysis(AFA),the long-range correlation(LRC) of soil moisture and long-range cross correlation(LRCC) between moisture and three types of radiation were analyzed at different timescales and soil depths.The results show that:(1) Persistence of soil moisture and consistency between soil moisture and radiation mutate at 18-d and 6-d timescales,respectively.The timescale variation of soil moisture persistence is mainly related to the influence process of radiation on soil moisture;(2) Both the soil moisture persistence and soil moisture-radiation consistency vary substantially with soil depth.The soil depth variation of soil moisture persistence is related to the influence intensity of radiation;(3) From 2–6 day timescales,LR displays the strongest influence on soil moisture at depths of 2–10 cm through negative feedback of radiation on the soil temperature.The influence intensity decreases with depth from 2–15 cm.Therefore,the soil moisture persistence is weak and increases with depth from 2–15 cm;and(4) At more than 6 day timescales,SR and NR display a stronger influence on the soil moisture persistence at depths of 2–40 cm through positive feedback of radiation on the soil temperature,especially at depths of 2–10 cm.This influence also weakens with depth.The soil moisture persistence at depths of 2–10 cm is the weakest and increases with depth from 2–40 cm.The research results are instructive for determining timescales and soil depths related to soil water in hydrological models.
基金the Science and Technology Program of Sichuan,China(No.2016FZ0033)the Science and Technology Program of Sichuan Luzhou,China(No.2016-S-63(1/3).
文摘The effect of crystallization conditions of poly(butylene succinate)(PBS) component on the crystallization of poly(tetramethylene oxide)(PTMO) component in their segment block copolymer, with a higher PTMO content(PTMO mass fraction is 67%), was investigated by DSC and temperature-dependent FTIR. It is found that the isothermal crystallization time(tIC) of PBS has an effect on the crystallization behavior of PTMO component. Perturbation correlation move-window two-dimensional(PCMW2 D) correlation analysis and generalized 2 D correlation analysis(2 DIR) were performed to explore the origin of this phenomenon. The PCMW2 D and 2 DIR results show that the correlation intensity peak observed at around 20 ℃ for PTMO is due to the PTMO chains movements forced by the PBS chains folded movements. If tIC of PBS at temperature of 20 ℃ is prolonged, more PTMO components are incorporated in the region between PBS lamellae and the peak at-7.6 ℃(belonging to less-constricted PTMO chains) changes smaller and even disappears, while the peak at-16.3 ℃ belonging to more-constricted PTMO chains gets bigger. A crystallization model was also established in this study. The results of tensile testing showed that tensile strength slightly increased and elongation at break decreased with increasing heat treatment time at 40 ℃.